Reduced Engine Power Sensor [Archive] - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

: Reduced Engine Power Sensor


Gerry Waddell
08-12-2007, 04:00 PM
The reduced engine power sensor on my 2003 Trailblazer keeps activating.
I have had it in the shop 5 times. Dealer has installed software updates, but
problem persists and is getting worse. They have no idea what is causing
this. Factory support has been no help. Looking for solutions.

rcam81
08-12-2007, 04:26 PM
Welcome to the group. Something that you could do to help us diagnose your problem is to fill in your profile. Once you do that, the info will start flying.

blandmiller
08-12-2007, 11:20 PM
Welcome to the site.

The "reduced engine power" message is not a sensor. It is a message from the PCM that some sensor(s) or operating parameters are not reporting correct information to the PCM or the sensor(s) are providing information that is causing the PCM to protect the powertrain. The problems that can cause a reduced engine power are probably too numerous to list.

Next time it happens, make sure you get the DTC codes and post them to the site. You should get many responses once you have some codes that everyone can make sense of. There are several very helpful members that can start to diagnose the problem with a little additional information.

I also agree with rcam81, fill out your profile so we all know what configuration you are driving.

tblazed
08-13-2007, 12:08 AM
A friend of mine had his accelerator pedal sender-resistor gizmo fail and got the reduced power light. Replaced the pedal ass'y and that fixed it. I think it set a code so you might get that checked somewhere like AutoZone who will do it free. A stored code should lead you in the right direction.

Towpig
08-25-2007, 02:28 AM
My wife had this happen on the 06 5.3L and it turned out to be the throttle body and the ignition switch:confused:. Truck wouldn't go over 30MPH and the reduced engine power light was on. It definitely didnt protect the motor because right now it's in for a new long block.:worried:

Nukedog
08-26-2007, 05:32 PM
My wife had this happen on the 06 5.3L and it turned out to be the throttle body and the ignition switch:confused:. Truck wouldn't go over 30MPH and the reduced engine power light was on. It definitely didnt protect the motor because right now it's in for a new long block.:worried:


Apples and Oranges...

Towpig
08-30-2007, 07:22 PM
Be it the pedal or the throttle body, it is about the same. The sender or the receiver, the signal did not reach it's destination. But, I do know the computer does not shut down engine power due to signal input. It only tells you the drivetrain is not functioning properly. +/- 7-10% expectancy.

How much money would GM make if they shut down an engine due to heat or oil pressure, or had the DIC tell you exactly which sensor or part went bad?:undecided

accplu
09-04-2007, 09:58 PM
Just bought 2005 GM Buy Back loaded EXT with 25k on it. Immediately after brake controller was installed under dash, the reduced power thing happened with a check engine light on. Dealer found wiring harness under dash problem and fixed it.

sarge355
03-20-2010, 05:52 PM
I am looking for some assistance. My 2003 Trailblazer has 63,000 miles and has been experiencing the reduced engine power problem. A GM dealer has replaced a fuel sensor, entire wiring harness, computer, and it still is occurring. The only other thing they plan to try is the accelerator assembly.

Any thoughts on whether or not this should fix the problem??? I've been a very loyal GM owner, but this experience has me reconsidering that...

the roadie
03-20-2010, 06:43 PM
On whose dime are they doing that INSANE and EXCESSIVE amount of guessing? :eek:

What exact code shows up in the computer when it goes into REP mode and sets the SES light?

Typically the code will point to the throttle body or the accelerator pedal. There's a TSB that it might also be chafing in the wiring harness from the PCM to the fan clutch, or a failure in the fan clutch. We're very familiar with it here on trailvoy - hard to believe the dealer isn't.

bstromback2002
03-20-2010, 11:55 PM
Like roadie said you really need to find out what the codes are setting the REP light.

I had this problem once and I ended up replacing the throttle body which was the most expensive thing i have had to do to my truck, but no more REP light.

sarge355
04-12-2010, 08:42 PM
I have shelled out $1,200 for the fuel sensor, accelerator assembly, and wiring harness. The computer was covered under a warranty of some type. After the 4th trip where they replaced the accelerator assembly...it has been fine for the last 2 weeks...until today. Same problem....I won't pay Reeder Chevrolet another dime to fix this...taking it back tomorrow...any suggestions???:mad:

the roadie
04-12-2010, 09:13 PM
We gave you suggestions on 3/20 and you didn't respond. I'm betting on it being the fan clutch or the harness. Have those goofs EVEN READ the TSB?

What is the code?

sarge355
04-12-2010, 09:26 PM
Sorry for the delayed response...I'll ask tomorrow what the code is....they actually replaced the fan clutch almost 2 years ago...hard to believe this is a licensed GM dealer...

mimosa-usa
09-22-2010, 10:21 PM
On whose dime are they doing that INSANE and EXCESSIVE amount of guessing? :eek:

What exact code shows up in the computer when it goes into REP mode and sets the SES light?

Typically the code will point to the throttle body or the accelerator pedal. There's a TSB that it might also be chafing in the wiring harness from the PCM to the fan clutch, or a failure in the fan clutch. We're very familiar with it here on trailvoy - hard to believe the dealer isn't.

I am having the same issue. Local mechanic said the code was the accelerator pedal. Put 2 aftermarket ones on and worked ok for about 3 weeks each time. Now the dealer says that they could put on a $380 GM pedal but no guarantee that it will fix the problem. (big surprise). Buy the way, the fan clutch sounds like a Tomcat ready for launch and that is another$800. Are these problems related? Seemed the Reduced Engine Power atrted back when I noticed the fan clutch starting to go out.

the roadie
09-23-2010, 12:36 PM
...Are these problems related? ...Yes. I'd predict 90% chance it's in the fan clutch or its wiring harness. Just pull its connector off and see if the REP light goes out. You might get a SES light with a fan clutch code, but it's a good experiment to do. Fan clutches can cost less than $200 if you're doing it yourself. There have been reports of erratic aftermarket APP sensors that GM parts can fix. Intelligent use of a high-end scan tool can distinguish this sort of problem from a bad fan clutch. Tell the mechanic that the fan clutch, APP, and Throttle Position Sensors all share the SAME 5V reference circuit. But they have access to schematics and TSBs that say the same thing.

sBoddie
07-28-2011, 08:16 PM
First let me say thank you to all who have posted here. I'd been in lurk mode since before I even registered as a member, and never needed to post a question on account of the wealthy search.

My problem with the REP started a month ago on a hot afternoon after (coincidentally?) the truck had earlier run out of gas. GM service replaced the ignition switch. Next afternoon it got hot, driving in traffic, engine quits again. Then my old mechanic digs through the TSB's on it to trace it to some voltage problem, and thinking the sensor in the throttle is sending some faulty data back to the PCM, recommends replacing that. I put in a new throttle body myself yesterday.

After an hour of driving this morning, it quits again. What I have found gets me back on the road when stranded is to disconnect the battery cables, leave the hood up, and after it cools off 20-30 minutes its starts and runs fine.

So when I get it back home I find this thread on the fan clutch connector. So I disconnect that (5-wire @ top-right of radiator shroud?). It won't start. Cranks strong, no spark. Plug it back in, still no start. I got the codes (P0689; P2101; P0442; P1682). I left it sit there, an hour later came back, now it starts. With it running, same 4 codes + P1516 added.

Pulled off the connector again, no change. Other possibilities he had also suggested was bad battery cable, loose ground under fuse box... any other ideas? Way out of warranty, and the service guy @ GMC seemed to want to jump down the rabbit hole on my dime.

Scott

sBoddie
07-28-2011, 08:30 PM
Sorry... P0443. Typo.
If it were a bad cable or fuse box connection, why would it only do it when it's hot?

srb

sBoddie
07-30-2011, 01:05 PM
Judging by the "views", is this the second most common OEM concern?
Here's an update. Truck starts when cool. Disconnected fan clutch conn... still quits once it got too hot. In extreme temps (100+ weather) it may take a few hours before it will start again. As long as outside temp is <85 and I keep moving, it will run fine for hours until I hit traffic. Sometimes it will even make it to my destination if hot, but refuse to start again once it's turned off.

Plugged or unplugged, fan clutch seems to have no impact. It appears to only quit when I lift off the accelerator, like preparing for a turn or stop @ an intersection. I don't think it's ever done it with my foot on the gas. So it would seem to be a faulty voltage reading.

Anything besides battery/ground cable/fuse block I can look at diagnosing Monday when I can bring it in to somebody with the right tools? (see previous post for codes)

Replaced ignition switch and throttle body. Have NOT replaced APP or crankshaft sensor. Still original alternator/voltage reg.

It would seem to be something that only reacts to heat in the engine compartment. Similar to "TB shuts off when it gets hot" < http://forums.trailvoy.com/showthread.php?t=88932 > except it keeps going if cool enough outside.

The Roadie suggested having a scan tool connected when it dies. Easy enough to predict, if I can get somebody to go along with it. I'm just afraid of the dealer service dept insisting I jump down the rabbit hole to find it. I don't mind the process of elimination if the parts are cheap & I can do it myself. BTW - there's an ad post < http://classifieds.trailvoy.com/showproduct.php?product=4869&cat=2
> for a good throttle body if anybody else out there _actually_ needs one. :duh:

Thank you. I'm really sucking wind on this one...
Scott

sBoddie
08-08-2011, 06:57 AM
Turned out to be the fuse box (electrical panel) under the hood. Crack &/or shorted wire inside. $463 for replacement, $810 total for the day-an-a-half visit.

srb

wambachb
05-02-2012, 01:54 PM
Yesterday I was driving and all of the sudden my cars slows to 10 mph so I let off the gas and all it did was Idle and when I gave it gas it dod nothing but rev up the RPM's. I had it checked out this morning and the codes that is pulling up are P1271 and P1635 also another code comes up as PO420 #1 and PO420 #2 (the #1 is talking about the oxygen sensor but that has been replaced). Do you have any ideas on what is going on with my Chevy? Any help you could provide would be great. Thank you so much for your time.

Welcome to the site.

The "reduced engine power" message is not a sensor. It is a message from the PCM that some sensor(s) or operating parameters are not reporting correct information to the PCM or the sensor(s) are providing information that is causing the PCM to protect the powertrain. The problems that can cause a reduced engine power are probably too numerous to list.

Next time it happens, make sure you get the DTC codes and post them to the site. You should get many responses once you have some codes that everyone can make sense of. There are several very helpful members that can start to diagnose the problem with a little additional information.

I also agree with rcam81, fill out your profile so we all know what configuration you are driving.

jandesgns
05-08-2012, 04:07 PM
I am new to this post, just found it after researching my vehicle.

I just had a sensor replaced in the Gas Tank due to the recall (my gas gauge stopped working) And about (2) days later my vehicle starts having the Reduced engine power light, SES light and the stabillitrac light,

The codes popping up are P2135, P2138, and P0641. I had no problem with it prior to having the sensor in the tank replaced. I have 86,848 miles on the TB.

jandesgns
05-08-2012, 04:09 PM
Sorry post duplicated for some reason.

scottn04
06-01-2012, 03:02 PM
I just started having the Reduced engine power light come on. Code I'm getting is P1271. Please help!

ratlsnaktj
08-13-2012, 12:19 PM
Ive been randomly getting the REP light, stabilitrak off light, and SES (code its throwing is p2138). A little while ago I had the headlight turning off issue and swapped the fan clutch relay with the headlight relay. Is there any possiblity that the bad headlight relay that is now in the fan clutch relay spot could be causing the REP and SES lights to come on? It only seems to be happening on days when it really hot out.

I've ordered a new relay already to replace the bad one, just waiting for it to arrive.

sBoddie
09-02-2012, 12:35 PM
I've heard reports about the fan switch. But look at this post [08-08-2011, 05:57 AM] and have somebody compare voltage between the dash side and the engine side of the fuse box. Mine only did it when it was hot too.

ratlsnaktj
09-17-2012, 05:07 PM
I was thinking it may have something to do with overheating. It hasn't happened again lately but its been a little cooler then during the dog days of summer so maybe you're right. Is that a dealer only kind of repair?

sBoddie
09-18-2012, 10:09 AM
I'm tellin' ya... that's the rabbit hole I went down for 3 months. It has to do with engine compartment temp more than water/engine temp. I drove around with the hood latch popped to increase airflow and keep the speeds around 35-45 when I could and that helped it do it less.

You are going to need to bring it to a shop you trust that is comfortable with electrical/ECM work. THey will be able to compare voltage irregularities between the fuse box on the engine side to the interior dash side to find where it is.

sBoddie
09-18-2012, 10:24 AM
ratlsnaktj, the ECM getting faulty info from the throttle control (code #2138) has to be a result from a shorted wire or cracked fuse box. It is not cooling system related. DO NOT bring it to the dealer... they will only have you replacing the gas pedal assembly and throttle body, which are not malfunctioning and will not fix the problem (I've got a brand new $375 throttle body here in a box if you don't believe me :duh: )

Now that the temps are cooling down, whatever plastic part that is the culprit is not heating up enough to expand and cause the break. The next hot day you are stuck in traffic it will do it again. The second you lift your foot off the gas, the fail-safe will misread voltage for throttle position and shut down the engine.

ratlsnaktj
09-20-2012, 01:35 PM
That sounds like something pretty serious. Is there another issue that can cause the fuse block to crack?

sBoddie
09-21-2012, 09:02 AM
Not as bad as it sounds, for a qualified place. $800 and I was out. Spent 3 times that trying to find out that was it. I guess just age and engine heat gets to the plastic eventually.

blue03xlt
12-11-2012, 06:32 PM
03 Envoy 170K no modifications.

In May 2012 Reduced Engine Power light/Check Engine light started coming on randomly - it happens in hot and cold weather, local and highway driving, short and long distance. Lose ability to accelerate, have to restart engine.

Since then over 1/2 dozen visits, local independent shop has replaced throttle body, accelerator pedal/sensor, wiring harness/connectors, ECM. Tech assures me problem has stopped (test driving vehicle 300+ miles total) - and within a day of getting it back, problem recurs.

Apparently, they're test-driving it with panels off because twice when I stopped by to pick it up, they mentioned having to put the panels back on. So I'm wondering if it's possible that when they're replaced, they're crimping some wiring? Does this sound possible, and if so, what should I look for?

Same shop replaced Fan clutch June '11 (not sure if relevant, but others have mentioned it)

Before this, these guys treated me right, but I've spent over $1,000 so far, and I've lost confidence in them. When I do find a new shop, I want to be informed - what should I be expecting?

Thanks in advance - lots of good information here, looking for guidance as I pursue this. I love the vehicle and think it can keep going a while.
:crazy:

littlelav
03-16-2013, 10:34 PM
Hello guys, I am new here as well as a DYI guy. I dont know a whole lot about vehicals but enough to get me buy and save$. I am having this same problem, the Reduced engine power warning displays and wont go away. I have checked the wires at the TB as well as the pedal, cleaned my TB, cleaned and sanded my ground conections, the ones i could find anways. Disconected my battery. Hooked up a wire from the neg post of battery to the TB. Everything i have done isnt fixing the problem. Am i missing something, or do I have to replace my TB. Is there a way to check if the TB is working properly. Please any help would be much appreciated. It is a 2003 GMCsierra 1500 HD

blue03xlt
03-17-2013, 12:49 PM
As others have said elsewhere, if a fix isn't working try replacing an aftermarket part with an OEM part before going onto the next thing. Wish I had known sooner because it would have saved me 6 months and over $1,000 - to say nothing of the aggravation!

LKA
03-17-2013, 02:10 PM
Have the issue with the reduced engine power light says code 107 on the obd ive replaced the map sensor already and cleaned the throttle body to no result when i start the car its not on after about 10 sec it comes on and runs rough cant figure it out either

LisaPEI
09-11-2013, 05:01 PM
After 2 fan clutches and an OEM pedal assembly....I went into REM again with the code P1271...AGAIN...pulling my hair out.

Saul
12-02-2013, 02:32 AM
I've got a slightly different problem, but I still get the REP light. I get the REP light randomly (started last week) and once I pull over, turn off the engine, disconnect the Throttle Position Sensor (TPS) connector, reconnect it the problem goes away. It's happened about 5 times regardless of being on the hiway or streets. Once the connector is reconnected the problem seems to go away. So my thought the connector was bad and replaced it. I found the connector and pins and made my own connector. I started the car after being off for 4 days (waiting for connector parts) and the fan clutch made the normal high winding sound when cold and as soon as it shifted into 2nd gear the REP light came on! Major disappointment!!! I was a few hundred feet from home so I hung a U'y and popped the hood and did the disconnect/reconnect thing. Problem went away and the 15 minute test drive seemed all was OK. Next morning the REP light did not come on but came on after 7 minutes of driving. Pulled over, did the connector thing and the problem did not come back. I don't trust the fix and will not trust it until it stays off for months. Has anyone gone thru this connector thing? I saw a post on removing the rivets from the TPS and cleaning the inside...is that even worth doing? I cleaned the Throttle Body (TB) about 6 months ago when the Envoy would almost die everytime I came to a stop. Cleaning it out solved that immediately. Any help would be appreciated!!!:tiphat

BewstAdd1ct
12-02-2013, 10:33 PM
Anytime you've got a REP lite, codes are helpful.

Saul
12-03-2013, 02:20 AM
Newb so I'm learning the ropes... Here is what I have with regards to codes:

P0442
Evap Emissions Control System Leak Detected (Small Leak). This goes away when I replace my gas cap. I'm on my 4th Gas cap, as they seem to loose the ability to lock after about 6 months. Not sure why???

P0220
Throttle/Pedal Position/Switch B Circuit Malfunction.

P0120
Throttle/Pedal Position/Switch A Circuit Malfunction.

P0493
Fan Overspeed

P1516
Command vs Actual Throttle Position Performance (TAC module)

P2135
Throttle/Pedal Position/Switch A/B Voltage Correlation.

I read through the posts from others and was curious if there were photos of where (locations) the loose connections or frayed wires. I seriously think there are poor connections in the connector on the TPS only because if I turn on/off the engine numerous times nothing changes. If I remove the connector as quickly as I can the problem goes away. Any suggestions from anyone are greatly appreciated.

BewstAdd1ct
12-03-2013, 11:24 AM
I read through the posts from others and was curious if there were photos of where (locations) the loose connections or frayed wires. I seriously think there are poor connections in the connector on the TPS only because if I turn on/off the engine numerous times nothing changes. If I remove the connector as quickly as I can the problem goes away. Any suggestions from anyone are greatly appreciated.

No pictures, you're just doing a wiggle test right at the connector wires a few inches from the connector.

#PIP3089B: SES Light And Reduced Engine Power DTC P0120 P0220 P1516 P2135 - keywords accelerator actuator APP blade body connector connection DTC L33 L59 LH6 LR4 LM7 LS1 LS2 LQ4 LQ9 module position reduce sensor - (Oct 31, 2006)
Subject: SES Light and Reduced Engine Power DTC P0120 P0220 P1516 P2135

Models: 2004-2006 Buick Rainer
2005-2006 Cadillac CTS-V
2003-2006 Cadillac Escalade
2003-2006 Chevrolet Avalanche, Corvette, Express, Monte Carlo, Silverado, SSR, Suburban, Tahoe, Trailblazer
2003-2006 GMC Envoy, Savana, Sierra, Yukon
2003-2006 Hummer H2
2005-2006 Pontiac GTO
Equipped with a 4.8 5.3 6.0 or 7.0 V-8 Engine

--------------------------------------------------------------------------------

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:A vehicle may be brought into the dealer for a reduced power message, and DTCs P0120, P0220, P1516, P2101, or P2135.

The Throttle Actuator Control (TAC) / throttle body type trouble codes, may be caused by a loose wiring crimp at the throttle body connector, or a broken throttle body circuit.

Recommendation/Instructions:Complete the current SI diagnostics for any symptoms or trouble codes found. If a intermittent T/P or TAC module type code is occurring complete the inspections below.

 1. Inspect all related throttle body terminals for a loose wiring crimp. The loose crimp may be difficult to find, and the poor connection will be between the terminal and the copper strands of the wire. Wiggle test the individual throttle body circuits to see if the concern can be duplicated.
 2. Inspect the related circuits for broken wires inside the insulation. The outer wire insulation may look fine, but the internal copper strands may be partially broken. Breaks in the wires usually occur within 1 to 4 inches of the throttle body connector. Wiggle testing may also induce a trouble code to set.
 3. On C/K trucks complete SI procedures for voltage drop on grounds G103 and G104. Grounds G103 or G104 may be loose or corroded.
If a terminal crimp or a broken wire has been found, repair or replace only the circuits involved. There is a throttle body pigtail connector available through GMSPO, but installing this pigtail connector may cause other intermittent TAC module/TP codes at a later date. If this pigtail must be used, please follow the SI procedures for Splicing Copper Wire Using Splice Sleeves. (the proper Kent-Moore crimping tool must be used for this repair)

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed

Saul
12-03-2013, 12:31 PM
Initially I was doing a wiggle test by just moving the wires at the back of the connector. After about 3 episodes it no longer worked so I went for the whole connector. I unplugged it and plugged it back in, which has always solved the problem...until the next instance. I sprayed contact cleaner/lubricant and it worked for 1 week. In an attempt to remove the connector to clean the contact on the TPS itself, the locking tab on the connector broke off. It was so brittle that just completely fell off. The connector was held in place with a long zip tie for a week until I received parts to replace the connector. Hindsight I should have just replaced the connector and reused the original wires, but instead I removed about 2 inches of wire and made a connector with about a 4 inch pigtail. I crimped the contacts and reused the silicon seals (backside of connector). I soldered and heatshrunk the pigtails and put them in a larger Flex Loom tubing to protect the entire length of wires upto the connector body. I still plan on going back in and manually cleaning the contacts on the TPS to make sure any contamination or debris is removed.

FYI, I located the connector body for $0.92 and the crimp connectors for $0.06. I could not locate replacement silicon wire plugs so I reused the old ones. Part of my job (my real job) as an electrical engineer is to find replacement parts when legacy products have problems. Finding the connectors and crimps was not much of a challenge. If others want to make their own I can share all the details to save money.

Can I post pictures to show how I made the connector for others who don't want to spend $100 on a replacement connector?

BewstAdd1ct
12-03-2013, 02:16 PM
Sounds like it may have been terminal fretting due to weak tension. So the connector fixed it?

You should write a how-to on making that connector and/or make them and sell them to trailvoy members and over at fullsizechevy forums. Most people don't own the proper crimp tools to make them last.

Saul
12-03-2013, 05:13 PM
Unfortunately I can't claim victory yet. I've had to unplug and plug the connector twice since I made the connector...which is why my next step clean the contacts on the TPS itself. I'll get to it sometime later tonight and post the results.

I'll post the connector info later once I get all the pictures in order.

I wanted to ask why do you think the Fan Overspeed code popped up? My Envoy has 203,000 miles on it and I've changed the water pump once at 150,000 miles. Do you think the "potentially" bad contact at the TPS is throwing the Fan Overspeed code?

A second question...how many times have you had to replace your gas cap? I'm on my #4 gas cap and they seem to only last 6 months??? My 2004 Cadillac CTS has 382,000 miles and same gas cap!

BewstAdd1ct
12-03-2013, 08:09 PM
I'd wager that an intermittent 0442 may not be a gas cap. I've never had much of a problem with either of mine, and the ones I replace at work due to cracking don't come back.

The fan overspeed code can't be caused by the evap system, though it can cause the REP light to come on.

Basically the fan has to be over 6800 RPM for that code to set, and if it were, you'd know it. The power would be anemic at higher RPM and it'd sound like a tornado under the hood.

Either that or the PCM thinks the fan is over 6800. Testing basically involves seeing what the PCM reads, checking continuity and terminal tension and likely replacing the fan clutch.

Saul
12-04-2013, 01:00 PM
I cleaned the TPS contacts and unfortunately 2 miles down the road the REP light came on. I jumped out (turned off engine first) and unplugged the connector, plugged it back in and a mile later the REP light came back on!!!

However, I did notice something new...its cold this morning (32C) and as I was driving I heard a high pitch whine coming from the speakers. The radio was off and from my college years of installing car stereos and car alarms, that used to indicate an open ground. Securing the ground wires used to cure the engine whine in my stereo installation days. I need to find out where everyone suggest tightening the ground wires. So far I recall one is under the fuse box (reported by a member who was having the REP issue), the others are near the back of the heads (not sure where???). I will check the main ground going to the ECM as well.

I also noticed my oil pressure was not at 40 as it usually is. It was closer to 30 or slightly less. Maybe this is another hint. I did have a bad oil pressure sensor 3 years ago and it popped up the REP light however it did not reduce the engine power (that was interesting).

Anyway, I'm a little frustrated because the problem seems to be at the TPS connection and I am thinking about ordering the aftermarket Dorman TPS. Any past experience with Dorman? I've never heard of them and AC Delco does not seem to sell just the TPS. If the connection issue is internal to the TPS, then cleaning the connector will be useless. I may be moving the contact internal to the TPS just enough until the next bump in the road.

Any advice is appreciated.

Oh, by the way, I also head a ticking noise through the drivers side pillar what appears to look like a some sort of speaker/microphone about head high??? Not sure what that is!

Thanks!!

BewstAdd1ct
12-04-2013, 01:40 PM
The 'speaker' is actually the interior air sensor 'aspirator'. There's a fan inside and they buzz sometimes. Sometimes you can remove them and shake them or change the angle that they sit and it will go away.

TAC module ground at g108
8 cylinder: On the forward left side of the engine block, below G110

Saul
12-05-2013, 03:05 AM
Thanks for the info on the aspirator. I will tap it a couple of times to see if it calms down.

I will look for the ground point and tighten up any loose hardware if I find it.

I am going to reverse my approach. I am going to leave the engine running and begin the wiggling and tugging on wires at the TPS connector to see if I can trigger the REP fault. If I can reproduce it I can focus on the specific wire and see if I need to open up the TPS or replace it completely if its internal to the TPS. If I cant reproduce it, I will move down the harness and see if I can find any signs of worn or damaged wires.

Have you seen the thread (not sure which forum or web site) where someone shows how to remove the rivets and clean the inside of the TPS? Is that something you recommend? Have you done that before or know of anyone who has done that successfully?

BewstAdd1ct
12-05-2013, 05:00 PM
No to the last one, haven't seen it, no experience with it, at the dealer we usually just replace the throttle body. I thought I saw something a while ago about a TPS kit being released but I don't remember which model it was for.

As far as the wiggle test, yes. I thought that's what you were doing, haha.

When you set the REP, you won't 'un-set' it until you cycle the key. Do it KOER and you'll know when you set the fault.

Saul
12-06-2013, 11:18 AM
Back to square one!!!! With Key On Engine Running (KOER: had to look that one up) I tugged on each individual wire and I could not get the problem to happen. For kicks I pulled the connector off and the fan-clutch kicked in and the tornado started (like you said)! I turned off the engine right away. The REP goes away with the connector back in place. My next steps are to check the ground wires going to the PCM to see if there is a voltage drop in the ground lines.

I thought I saw a write up on how to test the TPS with a volt meter. I am going to locate that and see if the problem is internal to the TPS. I am tempted to replace the Throttle Body but want to make sure that's it before buying parts randomly. With a little over 200K miles, its probably not a bad idea anyway.

Found the best price for a new Throttle Body at gmpartsclub.com for $188 (part number 12570800, which I need to verify is an ACDelco part)

gretz99
12-30-2013, 12:43 PM
I am sorta having same issue, getting codes 1516 and 1125, ive cleaned and now changed the throttle body. Had all grounds and wires checked, changed ign switch, changed wires and plugs. Even had the pedal itself changed twice(pedal is aftermarket, everything else oem). As i drove down streets, my check engine and reduce power pops on, usually when i am being slowed up by grandparent driveres(35km per hr). Any ideas what to try next?? I am lost

TMBLDWN
01-07-2014, 06:11 PM
I've had this problem after installing my cold air intake system. Apparently, the coils were stretched because of the airflow that suddenly was being produced, and that's why that light came on for me.

Saul
04-09-2014, 11:52 AM
Hey folks, after a long fight with a severe flu, down for a month or so, then traveling to France on business, I finally got back under the hood about a month ago. I went ahead and took the risk of buying a new Throttle Body from GMPartsCenter.net for $209.77 (part number 12570800). I also purchased the seal directly from our local dealer ($25) which was not really damaged but at this point I wanted a complete replacement of all parts to make sure air leaks would not be in question.

Its been a month and no more REP message so I can claim victory for now. I want to thank everyone that helped walk me through the troubleshooting steps to eliminate "things that are not broke". Without your help I'm pretty sure the dealership would have had close to $3000 of my money...which I am glad not to had over and spend it on something else.

slimsybutton
06-15-2014, 11:16 PM
So my wife drives an 06 blazer and it stalls out gives reduced power and the check engine light.......but here is the kicker this happens complete randomly

Sephy
06-18-2014, 10:49 PM
Hey guys, I know this is an old post but my 03 th is killing me with this REP light. It only happens when I when I try to accelerate quickly. It pops up and slows down the truck. Once I pull over, shut it down and start up again am good to go.

Please help me out here. Imagine having have to pull over on the I-90 with your family in your car. (Not a good look)

Saul
07-03-2014, 09:57 PM
I had the same problem and after months of troubleshooting my problem ended up being my Throttle Body. I have a 2003 Envoy and purchased my Throttle Body from PartsCenter,net. It was less expensive than Rockauto and I got it for $209.77. I have the 5.3L Envoy XL and my part # was 12570800.

I also tried replacing the connector on the TPS and it did not help. I did not change the accelerator pedal, which would have been my next purchase of the TBS did fix it.

Good luck.

wdyoung
09-04-2014, 08:13 PM
Throttle body was replaced a few months ago. (SES and REP lights were on.) Nearly a grand. Few weeks ago, same lights. P2135 code. By the time I got to the shop the next morning, REP was out (SES still on...but ran fine). They told me it was a throttle body code, but nothing wrong with throttle body. Something about 5v references, and they don't know which one it is....since all seemed fine (except for P2135 code) while it was at their shop. Today, same deal. Turned truck off, back on...SES on but REP was out. Thankfully, I could get home ok. If I take it to the shop tomorrow, I'm afraid they'll tell me same thing as last time..."we don't know where the problem is, since REP is not on". (??) 2004 Trailblazer, 155k. Few issues with it for ten years (except it needs an a/c mode actuator right now...but that can wait).