[vlaukin]

Thank you D, this was confirmed and verified through web searches on those specific units. Lessons learned! Something to consider when purchasing one of these units. Here in CDN, that seems to be over $200 +/-.

"UPDATE"
I did go over and service all the ground points and inspected the ABS module. This unit appears to be engaging and disengaging normally. When I disconnected the "Positive" terminal and drained the system, it took mere seconds for the errors to re-appear, key on and no start. This appears to indicate an open circuit or short circuit, so most likely, a Wheel sensor has malfunctioned.
I am having trouble getting any readings (ohm) from the frame junction connector to the wheel sensor. I just cannot seem to get a good connection on any wheel. I think I will try to locate some connectors to make a custom plug I can "hard connect" to my meter. Any tips?

Then there is this: "Steering Wheel Position Sensor"
Put this in your google search:
"gmc sierra chevy silverado service stabilitrak service traction control"
The first link looks very promising, but there is information missing and it could also be a dozen other things. I have found a PDF which lists all the GMC OBD codes, including ABS. The Steering Wheel Position Sensor code is: C0455. So, once again, a proper scanner(ABS) is needed to confirm this.

 

[vlaukin]

UPDATE #2
I had a family member lend me an older Genysis Evo scanner and after I repaired it, it showed a wheel sensor was not reading. Previously, I tried to do an OHM test on the wheel connectors to the wheel sensors, but I had no luck getting any type of reading doing that.
Bottom line: get it scanned, it could save you time and money!

 

[vlaukin]

UPDATE FINAL..?
After spending some time on the truck, full tune up, oil change etc, it's running super!
I decided to remove and clean the rear brake sensor mounts and the code disappeared.
This was a false positive, as I later discovered the error would pop back on when I would brake to a stop.

Long story short, it was the brake switch. The faulty brake switch will throw 3 codes:

• ABS
• Stabilitrack
• Traction control

The tell was when I could not get the vehicle out of park on a couple of occasions!
FYI, all good and enjoying the ride again...

 

[vlaukin]

You mentioned earlier a scanner showed a wheel speed sensor was not communicating. Did you repair that?

I had purchased a new sensor, but it remained un-opened due to the following:

After that scan pointed to the DRVR's side rear wheel sensor. I removed both rear sensors and clean the mount points.
The codes disappeared! BUT, when I would start to stop (touch the brake), the codes would come back. I would then
manipulate the connection at the frame mount and codes gone again. So I was preparing to diagnose a connection issue.

What happened after was totally unrelated. I was servicing my cargo trailer lights, so I connected the truck to test my work.
It was then that I discovered that there were no brake lights coming on the vehicle, but the trailer was working perfect.
This was also when the vehicle would not engage into drive on several occasions. So this was an obvious issue which resulted
in how I solved the problem.

I disassembled the switch to try inspect it and discovered the corroded points. It's an interesting switch which contains two
points, much like the old style D-cap coils we used to replace. I attempted to clean and try my work and the brake lights and codes
would come on intermittently, now the scan pointed randomly to either side rear wheel. So I knew I it was not a connection problem.

Been driving with a new brake switch for 1 month = no codes or issues... Returned the sensor BTWY.
;-}

FYI