Uh Oh...1st Major Issue With The Truck

[VT_Z71]

Driving up a mountain this morning at 70mph, pulling my trailer and quads, all of a sudden the truck starts dinging at me. Look at my guages and the red Brake warning light was on. Kept dinging at me for what seemed like forever, then the ABS light popped on as well. Now they are both on constant.

 

Truck just tripped 34k. Going to the dealer in a few hours. Glad it is under warranty, just hope they don't try some excuse like the lift and tires caused the ABS Module to go bad.

[gtivr6]

My dealer would have said some lame excuse like that. Hope everything goes ok

[music]

Driving up a mountain this morning at 70mph, pulling my trailer and quads, all of a sudden the truck starts dinging at me. Look at my guages and the red Brake warning light was on. Kept dinging at me for what seemed like forever, then the ABS light popped on as well. Now they are both on constant.

 

Truck just tripped 34k. Going to the dealer in a few hours. Glad it is under warranty, just hope they don't try some excuse like the lift and tires caused the ABS Module to go bad.

 

Most likely culprit is a ABS wheel sensor. I'll be curious to hear the outcome.

[wayland1985]

Subscribed...

 

 

I've been out of the loop for a while now... but I'm assuming GM figured out the ABS module issues from yester-year?

[Anthonyb]

Just put new wheels and tires on mine, but used the original TPMS. A week after the new wheels, I started getting error message and it showed no pressure in my right front. Took it back to Discount Tire and they had to replace one of my tpms sensors. I was told the battery in them dies after a few years and to expect this on the other wheels. I have less than 30,000 miles on my 2008.

[VT_Z71]

UPDATE:

 

Ran home at lunch. Disconnected the battery ground, swapped out the Blackbear modules and put the stockers back in. Started the truck back up, and everything is back to normal. No Brake or ABS lights remaining constant on the dash.

 

Took it to the dealer anyway to get checked out. Lights did not set off during the 5 mile drive. Therefore, I told the dealer that even though the warning lamps remained constant this morning, after sitting for a few hours they are now off. They tell me that even though they are no longer lit, since the ABS light was on this morning, that should have set a code that they can scan and determine the problem.

 

Which leads me to my fear/questions:

 

a) If a ABS code was set off this morning, where will it be stored? In the Blackbear PCM/ECM I just swapped out? Therefore, it not being in the GM modules I put back in, will the dealership even be able to determine a problem or find a code? If not, and there is a real problem that they can not find/determine (at least for now), I fear that I'll have to drive around with the stock modules for a while to see if there is a real problem, in which case hopefully after more miles of driving it will set off again and show up on the stock PCM/ECM to finally be scanned/fixed by the Dealer.

 

b) If I can't re-create the problem on the stock ECM/PCM, could it potentially be an issue with the Blackbear modules that I need to have Justin take a look at and re-program? I've never had any issues with the Blackbear in the 2 years or so that I've had it, however, I find it odd how obviously something set off my Brake & ABS warning lights this morning (even after cutting the truck off and re-starting) and now nothing is showing up once I put the stock modules back in.

 

Guess I'll have to wait for that call from the dealer.

[jro909]

it seems like the abs/brake light thing is becoming common now on gmt-900s...theres like 2 or 3 threads about people having the issue, so i don't think its the tune and yes the codes probably in the blackbear pcm..

[music]

Brings up an interesting question. Do the hand-held tuners, such as Diablo, clear the codes when you put them back to stock? You would think that they would leave DTC codes alone (actually, you should be able to read them yourself and then reload the stock tuning before a dealer visit), but I'm curious.

[C. Charles Hahn]

I guess I thought DTCs were stored in the BCM, not the ECM/TCM....

[redvett]

Engine/trans codes are stored in the PCM not the BCM.

[Stevens03]

Did you try and reset the BB PCM after the codes were set off? By disconnecting the neg. side of the battery you would have been able to do that. I'd assume that re-installing your BB PCM, the lights would be off too unless there's a real issue.

 

Let us know.

[VT_Z71]

Truck is in for service as we speak. Hopefully they can run whatever tests they have to determine if there is a real issue with the brake/ABS system even with the stock ECM/PCM back in. I'm not sure if they will merely attempt to pull codes (which I hope the ABS fault is stored somewhere other than the swapped modules), or if they have specific tests they run on individual system components (ABS module, each wheel sensor, etc.) to determine what was causing the fault in the first place. I guess if there is a real issue somewhere, when I disconnected the battery ground to swap ECM/PCM modules everything was reset, and in my short drive to the dealer the system did not detect the fault again to turn on the various warnings.

 

I'm really hoping they can either find a stored fault code, or test the system components to see what caused the issue in the first place. What I really don't want to happen is to be told they can't find any issues, and I take my truck back only to have the same thing resurface again in the future-----meaning swapping out modules again, another inconvenient trip to the dealer, waiting 45-minutes for the shuttle van, etc.etc.etc. PITA.

 

I'll keep you posted.

[C. Charles Hahn]

Engine/trans codes are stored in the PCM not the BCM.

 

There's no such thing as a PCM in a GMT900 truck. There's an ECM (Engine Control Module) and a TCM (Transmission Control Module).

[usmc3529]

haha, I am an expert at this lol. Been through it all. Im taking a safe bet by saying you probably had justin at blackbear enter in your new tire size in your tune. By doing that you have gone outside of gms frequency range and caused the abs/brake light to come on. when you put your stock ecm/tcm back in the lights did not come on because all 4 wheels are now sending the same speed signal to the ebcm but your speedo will be off.

 

Now the bad news, you will need to send justin back you tune and have him put the stock tire size back in(and gear ratio if you changed that too). you will then need to buy the hypertech in line speedo calibrator(200 bucks) you hook it up to your pc upload the new tire size and then plug it in to the back of your speedo cluster in dash( in provides a frequency change/calibration change that allows the vss to get the correct signal.

 

The code will be in the ebcm and will be a c0245(wheel speed frequency error) and it will only be in there if the lights are on(a hard fault code)

 

do not use a diablo or edge or any other tuner as the RARELY work to correct the tire size. They can go up a few increments but will 99/9% result in the lights coming on(if the blackbear caused the lights to come on so will any handheld). The hypertech is the only tool that can creat a new calibration signal that will allow the speedo to be accurate and not allow the lights to come on

 

The new brake system on these gms are a HUGE pain and there is NO WAY around it. The Rear speed sensor and front speed sensors tie into the ebcm and if the frequencys are off, the lights come on.

 

On that note there is nothing wrong with your truck. Just send back your ecm to justin, have him put in your stock tire size. The buy the hypertech, install it and you are done

[music]

The hypertech is the only tool that can creat a new calibration signal that will allow the speedo to be accurate and not allow the lights to come on

 

Assuming all of this is true (I have no experience myself, and I'm sure others will chime in), do the Hypertech programmers (e.g., MaxEnergy) provide accurate correction for tire size changes?