Subject: Four-wheel drive inoperative
Unit: Magna Power transfer case
Vehicle Application: 2008 Chevy Silverado 2500 HD
Essential Reading: Rebuilder, Diagnostician, R & R
Author: Mike Greer
DTC C0569 – calibration not learned
We finally had a big-enough snow this year to bring out the people with 4WD problems. This one was a 2008 Chevy Silverado 2500 HD.
It was from a tire distributor that has a number of these particular trucks. Their technicians had been trying to fix the issue of having no 4WD by putting various parts on it. They said that they had replaced the transfer-case motor and buttons.
I started out with the usual road test, scan and lift check to verify the problem. Sure enough, there was no 4WD and the transfer-case control module (TCCM) had every code possible stored. I thought I’d clear the codes and start out fresh.
CO569 came back immediately: system configuration error – calibration not learned. This was a new one for me. The next step was to get authorization to do electrical diagnostics, which they agreed to.
I thought maybe they had put a TCCM on it and it needed to be programmed. There were a lot of updates to it so I reprogrammed the TCCM to the latest software, but that didn’t fix it. The post-flash note said that the ATC motor had to be relearned. That was a big clue.
I first needed to know whether the problem was mechanical or electrical, so I pulled the encoder motor and shifted it into 4WD manually. What I found was that the shaft going into the transfer case was just spinning in circles. That was a problem.
This was a Magna transfer case, and I hadn’t worked on one of these before. I could see why it had a learn procedure; there is no blind spline to make it go on just one way, so it has to learn where the shift rail is. There was no sign of a leak but I pulled the plug and about half a cup of oil came out.
I needed a transfer case to make this one work, so we got a remanufactured transfer case and put it all back together, and it was time to do the relearn. You have to make sure that there are no codes in the TCCM or the relearn won’t work. When the relearn was happening I could hear the motor going forward and back. The relearn was done. The 4WD light went off and down the road it went.
Mike Greer has been with Certified Transmission for about 14 years. His experience as an R&R technician, transmission rebuilder and diagnostician gives him the benefit of having insights from various vantage points when evaluating a problem.