Engine Harness Contact with Underhood Components

There may be several engine performance conditions on some 2019 Silverado 1500 and Sierra 1500 models equipped with the 2.7L 4-cylinder engine (RPO L3B), including no start, no crank, engine runs rough, reduced engine power, erratic speedometer operation, blown fuses, and a combination of DTCs set. These conditions may be the result of the engine harness coming in contact with several underhood components.

If these conditions are present, there are several areas to check where the engine harness crosses over the top of the camshaft carrier cover. (Fig. 10)


Fig. 10


Inspect for engine wiring harness damage near each edge of the camshaft carrier cover. (Fig. 10A, #1)


Fig. 10A


Check the engine harness at the lower air cleaner housing. (Fig. 11)


Fig. 11


Also check the engine harness at the inlet radiator hose bracket and left front coil spring stud. (Fig. 12, #2) Under normal conditions, the engine will rock back and forth in its mounts, which may result in harness contact with the hose bracket. The contact will not be evident during inspection with the engine off. If this contact is found, it may be necessary to disconnect several engine harness connections to reposition the harness further inspection.


Fig. 12


In addition, inspect the engine harness at the left front upper control arm bushing. (Fig. 13)


Fig. 13


If engine wiring harness contact is isolated during inspection, use a seam ripper type tool to carefully inspect for internal wiring damage. If found, repair the damaged wiring following the wire to wire repair procedures in the appropriate Service Information.

Once repaired, protect the engine wiring harness at all points identified using Woven Polyester (PET) Electrical/Anti-Abrasive Tape.

Refer to the latest version of #PIT5677 for additional information.


– Thanks to Raymond Haglund

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