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2015 Chevrolet Silverado 6.6L Harness Damage
Posted to Technical Tips Forum on 12/20/2015 5 Replies

A Product Information Report (PIR) has been submitted identifying the condition described below, that may or may not exist on just this particular truck or others of the same build. A simple repositioning and tightening of a loose cable tie strap, may prevent the need for a subsequent repair on other vehicles.

The vehicle is a 2015 Chevrolet Silverado HD 4WD truck with 6.6L Duramax engine and Allison 6 speed automatic transmission combination. The truck was donated to our program by GM for training and has 10 km accumulated through plant and delivery.

Opening the hood to survey the engine compartment for the first time, the Transmission Control Module (TCM) electrical harness was found to be contacting the serpentine accessory drive belt. [TCM harness to serpentine belt contact] [Harness Chafed]

Further inspection of the harness revealed that the conduit was rubbed through [2015 Chevrolet Silverado 2500 HD LT, Photo] and the insulation was chafed through on one wire in the harness, leaving the conductor bare, but otherwise undamaged. [Conductor Insulation Rub Through]

Looking at the harness routing, the harness runs next to the engine harness at the left front of the engine and should make a high rise upwards before looping down under the upper radiator hose to make connection at the TCM, which is fastened to the radiator fan shroud.

A single cable tie was found loose at the base of where the engine and TCM harnesses are located. [2015 Chevrolet Silverado 2500 HD LT, Transmission Photo]

After repairing the wiring, conduit and re-affixing the label [2015 Chevrolet Silverado 2500 HD LT, Transmission Photo] the original cable tie was repositioned to maintain the TCM harness securely and routed with sufficient clearance from the drive belt. Moving the cable tie upwards about 3.5" did the job. [2015 Chevrolet Silverado 2500 HD LT, Transmission Photo]

Before fully securing the cable tie, clearance was verified and also that the harness loop to the TCM did not put the TCM connector terminals under stress from being at a too severe angle. Sufficient clearance and routing allows for engine movement without harness damage. [Secure Harness]

With the harness re-positioned and clearance to the drive belt verified [2015 Chevrolet Silverado 2500 HD LT, Transmission Photo] the cable tie was secured and the two harnesses taped together for added security.

Whether this might be an isolated incident or a common concern, if you service customer vehicles with this powertrain set up, it might be worth checking that the TCM harness is properly secured to prevent any need for a subsequent wiring repair.


Martin from British Columbia

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