Here's the latest on a previous reader's question involving a brand-new 2009 GMC Sierra, which went back to the dealership four times with an intermittent electronic fault. The problem involved several random symptoms including warning lights flashing on the instrument panel, unexplained application of the antilock braking system, and the transmission not coming out of first gear. During the diagnostic process, the GMC service department working on the truck was doing its best to keep the customer satisfied. It went as far as covering truck payments while the vehicle was down. But the GM higher-ups did not want to hear the terms "buy back" or "vehicle exchange." As expected, GM finally flew in an official General Motors' technician/engineer from Detroit to evaluate the problem. It seems the key diagnostic test the incoming tech employed was simply banging on the dash.
The shock triggered symptoms, which indicated a poor connection in the area. After further testing, including resistance checks on suspected circuits, it looks like the guys found the problem. I've been touching base with our reader as everything unfolded (he's a very patient guy) and got a copy of the final repair order. It appears they replaced the Electronic Control Module and a data link resistor before discovering excessive resistance (140 ohms) in the communication circuit between the BCM and the Transfer Case Control Module. They then replaced the electrical pin terminals at each end of the circuit. It's been about a month now (the problem was occurring on a weekly basis), and the truck has remained trouble-free, so we can assume it was a true fix. The truck owner seems content with the outcome, and following negotiations, the dealership owner threw in a complimentary set of nerf bars as icing on the cake.
If you have a technical question regarding your pickup, SUV, or van, feel free to contact Alex, a master technician with the National Institute for Automotive Service Excellence. Send a letter to him in care of Truck Trend Garage, 831 S. Douglas Street, El Segundo, CA 90245, or e-mail us at email@example.com. Please include the VIN with your question. Due to the volume of questions received every month, we cannot guarantee that everyone's question will be personally answered or will appear in the magazine.
Can't wait for help with a problem you're having with your Truck or SUV? Ask the expert we trust here at Truck Trend Garage — visit Alex Steele at www.RealWorldAutomotive.com.