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New Throttle body???

46K views 23 replies 12 participants last post by  ddgm 
#1 ·
I havent posted here in a while but I have a feeling i will be a regular in short order.

I have an 06 Envoy Denali and have had various issues with what I will call electrical problems. (ignition switch changed twice, gear select sensor, some solenoid that prevented the vehicle from shifting out of park, PCM re programmed, ECU Reprogrammed, cam sensor, some gas pedal sensor, and a few other items that I cant recall just now).

Anyway, vehicle has 65k and in the last 2 weeks has been displaying an egine light. Now after driving more than 5 min, it will go into limp mode with traction control turned off and a second larger engine light appearing. Dealer says theres 6-7 different codes (I dont know what codes yet). Extended warranty is paying for most but dealer is saying i need a new throttle body. I have enver in my life ever heard of any vehicle needing a new throttle body. Extended warranty said they will not pay for a new one either ($560). WTF!?!?

I have had the throttle body cleaned every 20k by the dealer (based on how frequently the topic is brought up here) and now they say I need a completely new one. Have any of you ever needed a new one? What causes it to get so dirty/caked up to begin with?

With my wife out of work atm there is no way i can afford this. Any help or suggestions would be greatly appreciated. Thank you.
 
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#3 ·
Reduced Engine Power issues are usually caused by a mismatch of the sensors in the accel pedal OR the throttle body. To prevent runaway vehicles like Toyota had a few of, there are two independent sensors on the pedal, and they have to agree with each other at all times. If one breaks, it could fail in a way that wants to go to WOT. That would be bad. So there's two sensors.

Same way on the throttle body. The throttle body is controlled by a stepper motor, but it has to report back to the PCM how open it is. If there was only one sensor, it could fail in a way that would report back to the PCM that it was CLOSED, so the PCM would send a command to open more and more until, yet again, you could be at WOT and not want it!

You might have been the victim of misdiagnosis before, which can happen easily when you have intermittent electrical problems. A pedal sensor error can also come from a chafed wiring harness on the FAN CLUTCH even, because they share the same voltage reference circuit from the PCM. A good mechanic is keeping up with all the TSBs and documents that explain the subtle details of the control systems.

If you've been PAYING the dealer to clean the throttle body without having erratic idle, you might have been wasting your money. I also think you haven't been paying attention to the reports here, which is the I6 throttle body is the only one that needs cleaning, not the V8, because the V8 has a PCV valve that prevents gunk from getting the throttle body backside dirty, and the I6 design omitted this valve. If you were doing it yourself, you might have noticed the throttle body was ALREADY clean. The dealer might have been cheating you if they recommended it, but if you went in by insisting it needed cleaning, what were they to say?

What might be bad is the throttle body position SENSORS, and they might have been damaged by the excessive dealer cleaning. I think they are separately cleanable, so putting in an entirely new unit might not be necessary.

But if it is, and budget is an issue, then just get one from a junkyard. www.car-parts.com shows plenty of them in the $100-200 range. Also available on Ebay.

What kind of extended warranty contract will work on some parts of the engine control systems and not others? I don't get it.
 
#4 ·
Hi Roadie,

1) Thank you for you response!
2) The dealer recommended the tb be cleaned the first time. Since i remembered seeing it here ALOT I requested it the additional 2 times. It was only $50 each time I think so, while it sux it was done needlessly, its not the end of the world
3) Im going to talk to them again when I go to pick the truck up today but he clearly said the throttle body itself has to be replaced, not the sensors. Had he said it was only the sensors, I can understand them failing and probably would have never created this post. Unless the sensors are a built in part of the tb?? Why would they do that?
4) The factory warranty ran out @ 35k so weve been paying out of pocket for all of these electrical issues to the tune of over $2k. When we decided to buy out the lease and finance the truck I asked for a B2B extended warranty. They gladly extended it to 100k and told us EVERYTHING is covered (sans wear items) I didnt want to have to keep paying for this crap. NOW the warranty company tells us they will cover everything except for the tb. Makes no sense. That is not a wear item. So, Im having them fix everything that IS covered and I will battle the tb issue once I get the truck back.

To the guy that PMed me, depending on how things turn out I will gladly take you up on your offer.
 
#6 ·
Well, wife picked up the truck today and I guess maybe I do need a new tb if I keep getting these codes.

Heres the writeup they gave her.

Codes: c0455, c0196 - replace SWPS and reprogram VSEV. - $ 125 parts, $265 labor
---
Codes: p2135, p060e, p121 - reprogram pcm. $159 labor
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Codes: p0171, p0174 - No Action, could not confirm.
---

Also, off topic but related, when they called to say we could pick up the truck today they said my battery was showing weak cca (been 4 years and 65k so, ok maybe im due). They wanted $95 for a new one. Figured that sounded close to the right price, save me the hassle, why not...Im looking over the bill and they charged $106 labor. WTF!?!?!?!?!? $207.65 for a BATTERY!!!!!!! That #&^%$% service manager will have at least one new @$$whole by the time im done with him on monday!!!!
 
#8 · (Edited)
Effers couldnt give a crap about my complaint. Told me I should have done it myself. OK, onto the next GMC dealer. There are only 4 in a 15 mile radius of each other..... Stupid

Anyway, still getting codes, still pointing to the tb. So as soon as there is available fundage I guess I'm off to rockauto.com. Or would you gurus recommend oem GM replacement only for the tb. Or sorry, the "Throttle Control Actuator" :p

I would assume, make sure to disconnect negative battery cable, use new gasket, use proper tq not hulk strength and guess and give the truck some time with the key in the "on" position before starting to recognize the new sensors? Yes, no, any other tips?
 
#11 ·
Update

The truck has been out of commission for 2 weeks now. I checked everywhere I could online and no-one I found had the part in stock. All of them said between 5-10 days plus shipping time. So i bit the bullet and bought the part today at lunch from a Buick dealer near my office. $285 and about 25 min of work in the rain and I have a perfectly working truck again.

$120 more than I would have paid online but, not having to play taxi cab and listen to my wife B*** and complain about not having her truck back = Priceless.




Anyway, a few things I noticed once I popped the hood...
-The wires are wrapped in a protective tube and there is no place I could see tracing them back as far as I could where they could possibly chafed...thats a good thing.
-The bottom left blt was so loose I could have removed it by hand. The others were rather tight.
-The clamp holding the air tube to the filter box was loose.
-I havent looked under the hood in a few months but there seems to be something missing. Like a cover or something... Can one of you with a denali compare your engine bay to mine in the pic below?

 
#15 ·
The truck has been out of commission for 2 weeks now. I checked everywhere I could online and no-one I found had the part in stock. All of them said between 5-10 days plus shipping time. So i bit the bullet and bought the part today at lunch from a Buick dealer near my office. $285 and about 25 min of work in the rain and I have a perfectly working truck again.

$120 more than I would have paid online but, not having to play taxi cab and listen to my wife B*** and complain about not having her truck back = Priceless.




Anyway, a few things I noticed once I popped the hood...
-The wires are wrapped in a protective tube and there is no place I could see tracing them back as far as I could where they could possibly chafed...thats a good thing.
-The bottom left blt was so loose I could have removed it by hand. The others were rather tight.
-The clamp holding the air tube to the filter box was loose.
-I havent looked under the hood in a few months but there seems to be something missing. Like a cover or something... Can one of you with a denali compare your engine bay to mine in the pic below?


Nope... I have an '06 Denali and my engine looks exactly like yours. the only engine cover they have is that plastic piece that has "vortec" written on it which is there.
 
#16 ·
also... i'm having a similar problem. Mine goes into limp home mode and pulls up four codes all having to do with the sensors and the throttle control system. I tried cleaning the throttle body and it was good for about 2 weeks. Then it started doing it once in a blue moon. Now everytime I drive the car, it goes into that stupid limp home mode. I'm worried it'll cost more than just replacing the throttle body though. Did you fix your problem?
 
#17 ·
Depending on the exact codes (?), cleaning the throttle body is not the right response. Often, it's chafing on the wiring harness going to the fan clutch. The 5V reference used by the fan clutch, throttle body, and accel pedal sensors are all shared. A problem on any one of them or the wiring can cause the limp-home behavior you see.

You can try a careful inspection of the wiring to all three items, or pull the connector off the fan clutch (it will be fine in the winter time - just watch your temp gauge) and see if it gets better.

Other than that, post up the codes and or run a search, and see how others have coped in the same situation.
 
#18 · (Edited)
#1 - Roadie is the MAN.
#2 - I checked the wires on mine as far back as I could. Could not find a problem. Unplugged the fan clutch didn't make a difference.
#3 - The $500 something I was quoted was to have the dealer replace the TB. I called around to all the local dealers, looked online and found one near my office for more then online but they had it in stock for $200 something. Took me 20-30 min to swap out.
#4 - Dealer has suggested that they reprogram something now that I have a new TB to make sure the sync is 100% - whatever, its working fine for the last 15,000 and i dont want them touching my ride again if I can help it.
 
#21 ·
Hello,

Thanks to everybody who posted in this thread. It has helped me a lot.

I am having the same problem as the OP but I have only one code which is the throttle position sensor. I am pretty sure I just need to replace the throttle body but I would like to at least check for chaffed wirinf before spending the money.

So now the COMPLETE NEWB :duh: question:

Where is the wiring for my fan clutch? Is it the wires that plug into the top left of the fan shroud? If it is somewhere else I can't find it.

Thanks again.

Jeff
 
#22 ·
Throttle Body + Codes?

Hi guys, Here is my story. I've got an 03 Trailblazer 6 cyl 4x4 EXT with 167K. About 8 months ago I started getting lots of Check Engine light and enough that I bought a code reader. Most pointed to the Throttle Body in some sort of way but some were just impossible for me to understand.

I kept driving it and about 2 months ago the CE light went on and it went into limp mode (first time for that one). I pulled over and waited a few minutes and it started back up and I was able to drive it to a highly regarded repair company.

I was saving my money to get a lot of miscellaneous repairs done like fix the code problems, replace the windshield, and repair or replace the power steering pump as my power steering was completely gone.

The shop called me the next day and told me they were getting lots of codes and that the noise I was hearing (sounded like paper in the hearter/ac blower) was dry dog food and that I had a rodent problem. Evidently chipmunks had been storing dry dog food from the garage in the blower duct which I now find is quite common.

The windshield was obvious and the power steering pump was shot. The steering rack was just fine (one shop wanted to replace it). He told me it might take several hours of diagnostics to figure all the code problems and wanted to know if it was ok to proceed. Nice of them to ask and I told them I had decided it was cheaper to keep the car than buy another one so go ahead.

5 days later he called and told me the car was ready. They had replaced the throttle body ($250) since it was only able to work 2 of the test commands out of a total of 9. The power steering pump was replaced. The chipmunk problem with wiring was in the MAP wiring which was most likely sending all kinds of idiot codes and hopefully after replacing that small harness ($40) it would fix that problem. Total bill including parts and labor was $1240! What a deal as I thought it would be much more than that.

I've now had the car for two weeks and it's running like it should have with no more problems. With the money I saved I went to TireRack and bought a new set of Michelin radials for it for even more savings.

The shop was Adams Custom Engines in Sparks/Reno, NV. They have been in business for 43 years and do a lot of restorations from the ground up they are that good. I highly recommend them.
 
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