Allision Internal Harness Failure | Don't Get the Cheapest One!

In this video from Duramax Service Center, Nick addresses a transmission issue in a 2006 LBZ Duramax diesel truck. The vehicle was experiencing several problems, including transmission flaring, where the engine speed increases without corresponding acceleration, a torque converter that wasn't locking up properly, and the vehicle going into limp mode—a protective feature that limits performance to prevent further damage. Additionally, an error code P0762, indicating a "Shift Solenoid Valve 3 Stuck On," was detected.

Initially, Nick and his team suspected that the issue might be related to a sticking valve within the valve body, prompting them to inspect the transmission by removing the pan. However, the root cause turned out to be a faulty wiring harness. The insulation on the harness, which was an aftermarket product purchased from Amazon, was deteriorating and not properly rated for exposure to transmission fluid. This led to the wires being exposed and causing electrical shortages. These exposed wires were making unintended contact, triggering the error code and contributing to the transmission issues.

Nick emphasizes the importance of using genuine GM or OE-equivalent parts to avoid such problems. He points out that while aftermarket parts might be cheaper, they can lead to complex and costly issues down the line, as seen in this case. Replacing the faulty aftermarket harness with a quality, manufacturer-approved part is recommended to ensure proper insulation, compatibility, and long-term reliability of the vehicle. This situation highlights the risks associated with using subpar aftermarket parts in critical vehicle systems.