Check engine light? [Archive] - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

Bodyslide

02-08-2007, 10:15 PM

Did you remember to do this?

READ THIS STEP IN FULL) Insert the ignition key and crank (start) the vehicle, if it fails to start and the "Service Engine Soon" and "Security" lights come on, leave the key in the "Run" position.

Note: Some have reported that the Passlock System instantly learned the new PCM, but this is rare. When you crank the truck as instructed in the Step above, if it starts, you are good to go. However, if the truck doesn't start, then you will have to allow the vehicle to sit with the ignition in the "Run" position and follow these Steps:
A) Once the PCM has been installed, insert your key and attempt to start the truck (it won't start). The Security and Service Engine Soon lights will illuminate.

B) After 10 minutes, the Security light will go off, you will need to turn the key to the OFF position, wait 5 seconds, and attempt to start the truck again (it won't start). The lights will illuminate again.

C) After 10 more minutes, the Security will go off again, repeat this cycle one last time, when the security light goes out, turn the ignition OFF again and start the truck, at this point it should crank and start.

Nukedog

02-08-2007, 10:25 PM

My truck started immediately so that does not apply...???When you crank the truck as instructed in the Step above, if it starts, you are good to go.

Bodyslide

02-08-2007, 10:27 PM

I would go by an AutoZone and let them pull the code or unhook the battery for a few minutes to see if that will clear the code....Good Luck

PROSPHOTO

02-08-2007, 10:34 PM

I would go by an AutoZone and let them pull the code or unhook the battery for a few minutes to see if that will clear the code....Good Luck

I would just get the code read, don't clear it :nono: ...if it really is a glitch, the PCM will shut the light off on its own in a day or two

Clearing the code/disconnecting the battery clears all of the data that has been stored in the computer, including possible information that can aid a technician in the diagnosis http://www.unixboard.de/vb3/images/smilies/sm-nachdenk.gif

Have you checked your gas cap? Is it tight? :duh:

Post the code when you get it read:)

Spong

02-09-2007, 10:41 AM

Nukedog, Did you send your stock PCM in or install a different one?

How do you like the tune so far?

Nukedog

02-09-2007, 12:04 PM

Sent stock one in - i only did an 87 tune but it does run better!

The code was P0526 which is fan speed sensor... Auto Zone re-set it so i will see if it comes back...

Spong

02-09-2007, 12:25 PM

Sent stock one in - i only did an 87 tune but it does run better!

Cool! I got the same tune. Do you notice the surge when the DOD kicks off?

Nukedog

02-09-2007, 03:03 PM

Why isa it PCM for Less can never address the questions i pose? I see they have been on here.

Not sure about the surge - The tune feels spongy in regular stop and go traffic...

Super 88

02-09-2007, 03:33 PM

Why isa it PCM for Less can never address the questions i pose? I see they have been on here.

Maybe you should send them a PM or email them directly with your question?

Spong

02-09-2007, 03:42 PM

Why isa it PCM for Less can never address the questions i pose? I see they have been on here.

I would e-mail or call. There's too many threads for them to read. Alvin is TOP NOTCH compared to other tuners I made the mistake of doing business with!

AlvinPCMforless

02-09-2007, 04:59 PM

Why isa it PCM for Less can never address the questions i pose? I see they have been on here.

Kelly did talk to you this mornign on the phone? Is there something else I can help you with?

Edit, I did see that your throwing a fan speed code. That has nothing to do with the tune.. Its probally just chance. You might want see what the dealership says as I understand its a common problem with some of them.

PROSPHOTO

02-09-2007, 05:32 PM

Sent stock one in - i only did an 87 tune but it does run better!

The code was P0526 which is fan speed sensor... Auto Zone re-set it so i will see if it comes back...

GM Bulletin #05-06-02-012B..."the Service Engine Soon (SES) or Check Engine light is illuminated. This condition may be intermittent and upon investigation, the technician may find either DTC P0480, P0526, P1481 or P1484 set....This condition may be caused by the cooling fan harness chaffing against the plastic guide it routes through. This contact may damage the insulation of the wires enclosed in that harness."

The dealer will replace the harness...but not until the code comes back http://www.aimoo.com/forum/images/messageicon/excalmatorymark.gif

Kelly_PCMforless

02-09-2007, 06:35 PM

Why isa it PCM for Less can never address the questions i pose? I see they have been on here.

Not sure about the surge - The tune feels spongy in regular stop and go traffic...

You know that we sponsor about 15 websites... we can't be on trailvoy 100% of the time. A more effective way of reaching us is by phone, email, or even a private message.

Your CEL is not even related to the tune we did.

Kelly_PCMforless

02-09-2007, 06:37 PM

GM Bulletin #05-06-02-012B..."the Service Engine Soon (SES) or Check Engine light is illuminated. This condition may be intermittent and upon investigation, the technician may find either DTC P0480, P0526, P1481 or P1484 set....This condition may be caused by the cooling fan harness chaffing against the plastic guide it routes through. This contact may damage the insulation of the wires enclosed in that harness."

The dealer will replace the harness...but not until the code comes back http://www.aimoo.com/forum/images/messageicon/excalmatorymark.gif

That is good information - thank you! Learn something new every day. :undecided

Nukedog

02-09-2007, 09:27 PM

Code came back again. No you did not talk to me this morning. There is no chaffing going on and it did no start till i got the PC back and installed. Guess i will send it to Alvin again. The fan doesn't seem to be pulling much air - like it is running at half speed and the temp now stick between 210 and 215.

I will look at everything more tomorrow. I am not doubting PCM on their tuning abilities i just find the timing odd.

PROSPHOTO

02-09-2007, 09:35 PM

Code came back again. There is no chaffing going on and it did no start till i got the PC back and installed.

I don't know about the tune, but I'll bet this isn't where you looked http://www.aimoo.com/forum/images/messageicon/excalmatorymark.gif

http://memimage.cardomain.net/member_images/7/web/2551000-2551999/2551515_21_full.jpg

Nukedog

02-09-2007, 09:38 PM

I'll check but it didn't do it when the vehicle was turned off and ECM?TCM shipped but it does do it now. Maybe a coincedence.

AlvinPCMforless

02-10-2007, 01:08 AM

I'll check but it didn't do it when the vehicle was turned off and ECM?TCM shipped but it does do it now. Maybe a coincedence.

Its just a coincedence. Theres nothing I can do to make it cause this code. It is a common problem as there is a service builitin about it.

And sorry, I over heard Kelly talking on the phone that sounded like the exact same senerio.. I figured it was taken care of.

Nukedog

02-10-2007, 09:54 AM

SPONG - yes it does surge when the DOD turns on and off.

jaylind

02-10-2007, 10:00 AM

SPONG - yes it does surge when the DOD turns on and off.

What's DOD? I am ignorant on this acronym.:duh: Thanks
Jay

PROSPHOTO

02-10-2007, 10:08 AM

Displacement on Demand...Shuts down cylinders when they are not needed (Hwy driving, light acceleration, etc.). The engine can run with only 4 cylinders...up to 8

Spong

02-10-2007, 11:29 AM

SPONG - yes it does surge when the DOD turns on and off.

I'm glad to hear it's not just me then! We were't sure if it was because of the other mods I have or what.

This gives Alvin something to figure out. :D

Nukedog

02-10-2007, 02:28 PM

Yep - it's not bad but it is noticeable..

Spong

02-10-2007, 02:55 PM

Yep - it's not bad but it is noticeable..

When I had the POS Wait4me tune installed, it was HORRIBLE! Take what you feel now times 20.

AlvinPCMforless

02-10-2007, 09:00 PM

When I had the POS Wait4me tune installed, it was HORRIBLE! Take what you feel now times 20.

If you guys are interested I can delay it from coming on period. I don't see it helping you guyus that much in gas mileage because my SS 6.0L with 4.10 gears gets 15.5 city and 18-19 freeway.

Spong

02-10-2007, 11:02 PM

If you guys are interested I can delay it from coming on period. I don't see it helping you guyus that much in gas mileage because my SS 6.0L with 4.10 gears gets 15.5 city and 18-19 freeway.

Honestly, I've wondered about shutting it off totally. I wonder if the DOD going of and on constantly doesn't maybe hurt the MPG a little. :undecided

AlvinPCMforless

02-10-2007, 11:18 PM

It might be a good thing to experiment with... Prehaps you can get 2 computers and try one with DOD and one without. I would take a stab at a good performance tune like what we do gets about the best mileage possible.

DOD seems a bit like a gimmic. The idea is kind of a combination to reduce pumping losses.. Think about trying to spin a engine against a huge vaccum.. thats what your doing at high load.

A goal is also to run the engine at a higher VE.. which happens at higher manifold pressure.. which usually happens under a big load. The load is artificially made by cutting 4 cylinders.

It also helps with having a more "saturated" charge per working cylinder which boost combustion effiecency.

Spong

02-10-2007, 11:22 PM

AlvinPCMforless

02-10-2007, 11:28 PM

I want to log at least one good out of town drive with the current tune and see what kind of MPG I get. I'm thinking about doing the E-fans so I'll be sending my ECM in for that so maybe we'll try killing the DOD at the same time.

The way the DOD sometimes kicks on and off several times going down the interstate and engages sometimes as low as 35 around town, I wouldn't miss it!!

Its too bad GM lets a factory tune go out the door that way.. Prehaps the change is just more noticeable with your modifications?

GM had a issue with the 93 LT1 cars also.. They had abad surge in them from the factory.. A few service bulletins later and they accomplished nothing! Turns out its somethign relatively easy to fix with a tune.. Maybe this is like the same case!?

Nukedog

02-11-2007, 02:12 AM

If you guys are interested I can delay it from coming on period. I don't see it helping you guyus that much in gas mileage because my SS 6.0L with 4.10 gears gets 15.5 city and 18-19 freeway.

My 5.3 with 3.42 gears gets 15/19 and my 5.3 3.23 Silverado did before that. Myabe just turning it off would be a good thing. My DOD cuts on as low as 40-45 and it can be herd thru the K&N.

quadhauler

02-11-2007, 04:03 PM

Displacement on Demand...Shuts down cylinders when they are not needed (Hwy driving, light acceleration, etc.). The engine can run with only 4 cylinders...up to 8

My TB doesn't have DOD and I have wondered how it works. If you would like to know, check this out. http://en.wikipedia.org/wiki/Displacement_on_demand

Basically, the cylinders stop pumping air since the valves are always closed. I think the gain would be marginal since the other remaining cylinders still have the frictional losses due to the spinning mass of the dead cylinders. Pistons, rods, bearings, lengths of crankshaft and the even the block and heads themselves (weight for the vehicle). Of course, once a motor is a 4 cylinder, it always is.. :)

ScarabEpic22

02-11-2007, 04:29 PM

I think there is a way in EFILive that you can shut off DOD completely. The parameters are there, but I have no way to test it, Alvin have you played with this at all? Im looking at the TB SS E40 ECM file, and it shows the option to disable DOD (its a E40 option, not a TB SS option as the SS doesnt have the proper internals to do DOD). Dont know if this helps at all, and I havent seen the parameter in any other tune file yet, so it might be a E40 only deal for now. (But doesnt the 5.3 use the E40 too, at least for 06?)

jaylind

02-11-2007, 10:04 PM

Displacement on Demand...Shuts down cylinders when they are not needed (Hwy driving, light acceleration, etc.). The engine can run with only 4 cylinders...up to 8

Thank you.

Nukedog

02-12-2007, 08:21 PM

I don't think the valves stop moving on the Chevy motors - the spark and fuel just cuts off. Remember the 5.3 is a single in the block cam...

PROSPHOTO

02-12-2007, 08:48 PM

I don't think the valves stop moving on the Chevy motors - the spark and fuel just cuts off. Remember the 5.3 is a single in the block cam...

The short version: Ignition remains in the de-activated cylinders, fuel ignition is disabled...

The valves DO stop moving via electronic engine command...Cylinders 1,7,4, & 6 lifters are hydraulically disabled rendering them useless. Special valve lifters consist of multiple components which are hydraulically controlled by the ECM through a valve lifter oil manifold assembly

The process is very detailed, but the end result is that the valves do stop moving

Hopefully this helps out a bit :D