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Truck Trend Garage: 2009 GMC Sierra Stuck in First

Alex Steele
Feb 16, 2010
Photographers: Courtesy of the Manufacturer
Q: I recently purchased a new 2009 GMC Sierra. By only 2000 miles, I've had the truck back to the dealership four times with computer issues. Without warning, the gauge cluster flashes and the ABS kicks in, causing the truck to slow and the wheels to lock up when leaving the pavement, all without touching the brake. On two occasions after restarting the truck, it wouldn't shift out of first gear. Diagnostic reports state that the computer has lost communication with the dash causing rough engine performance, transmission not shifting, ABS service required, and cold-start issue messages. The dealer said there's a repair bulletin issued on these trucks requiring replacement of connectors, possible moisture on connectors, air sensors, chaffed wiring, and poor grounding. The dealer has gone completely through the electrical and computer components replacing and repairing all possible issues. New software was downloaded. At this point they've been unable to resolve the problem. I've called OnStar each time to maintain a record of date and time for all issues. The dealer has been cooperative in maintaining record of repairs as a well as opened a case with GM. GM has contacted me about "goodwill" assistance, but at this point has offered no solutions or assistance.
Photo 2/2   |   06z 2009 Gmc Sierra 1500
A: Sounds like you're being very patient with this ordeal, which is good. This type of hard-to-find intermittent failure is frustrating for the technicians as well. I'm sure they're in contact with GM tech support looking for assistance on diagnosing the problem. After four returns, GM should have an engineer en route to the dealer to take diagnosis a step further. Give them more time to work on the problem, but you'll need to decide how long is too long before getting an attorney involved. Also ask the service manager if you can speak directly with the GMC zone representative with any questions. He's typically the top rung of the management ladder a consumer will reach. There are a few TSBs to which the technicians referred that involve diagnosing electrical intermittents. Some of these TSBs are somewhat generic, suggesting the importance of eliminating poor connections before replacing expensive components. From experience dealing with electrical issues on vehicles fresh off the assembly line, corroded terminals are probably off the table unless there was an unwanted water leak directly on a connection or component. It could be a module acting up, but other common faults are simply electrical connectors or terminals which were never fully seating into their cavity. I've also seen funky incidents like wiring flattened under a rivet during assembly that caused an intermittent short. You could give another service department a shot at it. Sometimes a fresh set of eyes does the trick.
How To Reach Alex
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 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

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