ABS and brake light turning on intermittently?

ROXY DOWNS REID

MEMBER
2005 CHEVROLET TAHOE
4.7L
V8
2WD
AUTOMATIC
200,000 MILES

Also, the A/C blower would quit. A/C still cold just no blower. I would move my steering wheel up and down until the lights went out or sometimes shut off and start the car to work. Now they both stay on all the time with no ac fan or cruise. The heater blows cold as well. ABS fuse is good, brake fluid full, ground wires behind front driver's tire are clean and tight. All my sensors are working and reading tires PSI. Any help would be appreciated.

1 Reply

KEN L

MASTER CERTIFIED MECHANIC
42,904 POSTS

These systems are tied to the PCM which sounds like it is going bad, but to be sure we need to do a CAN scan which is easy, and the scanners are cheap on Amazon, this will go over the entire car to let you know what's going on and if the PCM is bad.

You can get a CAN scanner (Controller Area Network) from Amazon for about $30.00.

Here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

Here is a scanner link:

https://amzn.to/3o41KcZ

Here is how you can replace the PCM in case this is what comes up as the problem. You can get a programmed PCM by searching Google or Ebay.

Powertrain Control Module Programming and Setup

The following service procedures require either a programming or a setup event preformed for a complete repair.

PCM Replacement
If the powertrain control module (PCM) is replaced, the following procedures must be performed:
1. The PCM Reprogramming-Refer to Service Programming System (SPS) in Vehicle Control Systems.
2. The CKP Variation Learn
- Refer to CKP System Variation Learn Procedure in Computers and Control Systems - 4.8L, 5.3L, 6.0L (LR4, LM7, LQ4, LQ9, or L59).
- Refer to CKP System Variation Learn Procedure in Computers and Control Systems - 8.1L (L18).
3. The Theft Deterrent Programming-Refer to Programming Theft Deterrent System Components in Theft Deterrent.

PCM Reprogramming
- If the PCM needs to be reprogrammed, refer to Service Programming System (SPS).
- Engine Oil Life Remaining-When available, use a scan tool to reset the Engine Oil Life Remaining back to the original percentage recorded before the module was reprogrammed.
- Transmission Fluid Life Remaining-When available, use a scan tool to reset the Transmission Fluid Life Remaining back to the original percentage recorded before the module was reprogrammed.

Setup for Component Replacement
The replacement of some components will require a setup procedure for complete repair.

If any of the following components are replaced, a CKP Variation Learn Procedure must be performed.
- Engine Replacement
- Any engine repair that disturbs the CKP sensor or its relationship with the crankshaft reluctor wheel
- CKP Sensor

Check out the images (below). Please let us know what you find. We are interested to see what it is.

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