2012 GMC Sierra 3500 HD Repair and Maintenance
A guide to problems, costs, maintenance and repair for your 2012 GMC Sierra 3500 HD
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2012 GMC Sierra 3500 HD ProblemsReduced Power and Check Engine Light
The GMC Sierra 3500 HD uses a throttle position sensor (TPS) which commonly fails and causes:
- Check engine light illumination
- Reduced Power message
- OBD trouble code P2135
This issue is related to the throttle position sensor, and can be caused by faulty wiring to the TPS, bad connection at the TPS, or a failed TPS.
To correct this issue, the wiring harness, connector, and throttle position sensor must be inspected, tested, and/or replaced. The most common cause is a faulty TPS.
2012 GMC Sierra 3500 HD RecallsIgnition Switch
The ignition switch actuator can bind causing the ignition switch to stick in the "start" position. If this were to occur the actuator can unexpectedly release, cause the ignition switch to snap back into the "Accessory" position. This would cause the engine to turn off with an associated loss of brake and steering power assist. If these conditions were to lead to a crash the airbags may not deploy as expected. Dealers will inspect and replace the ignition lock housing as necessary to correct this concern.
Vehicles equipped with a 6.6L diesel engine and dual fuel tanks are being recalled because the transfer pump that moves fuel from the rear tank to the front tank could cause the fuel gauge in show the incorrect fuel level. The engine could stall unexpectedly, increasing the risk of a crash. Dealers will inspect the fuel transfer pump and replace it as necessary to correct this concern.