During a recent icy-cold morning startup in the High Sierras, my Silverado battery voltage dipped a bit low while cranking. The diesel engine started, but I was rewarded with an illuminated check engine light among other issues. After returning home I retrieved codes and discovered a startling batch of them including multiple communication errors and the dreaded turbo vane position sensor code. It’s a $700 part. Yikes. Thinking it odd the codes all set immediately after the slow crank, I cleared them, and they have never returned. Just a momentary loss of memories had occurred, but it was enough to cause all this plus wipe out radio stations, clock, memory seat positions, and emissions monitors. The truck relearned the needed engine, emissions, transmission and transfer case memories within an hour or so of driving, the control modules all shook hands successfully, and I reset the others. Time for two new batteries.
With vehicles more sophisticated than mine, it’s certainly likely that professional service may be needed to perform relearn procedures in the event of a dead or disconnected battery. In addition, I would never, ever jump-start a modern vehicle without first consulting the operator’s manual for any special concerns and being absolutely sure of proper cable polarity. Most relearning can occur fairly quickly, if the right operating conditions are presented or are initiated using a scan tool.
Brad Bergholdt is an automotive technology instructor at Evergreen Valley College in San Jose, Calif. Readers may send him email at email@example.com; he cannot make personal replies.
Distributed by MCT Information Services.