Wiring Harness Routing and Engine Performance Conditions

There may be several engine performance conditions found on some 2019-2020 Silverado 1500 and Sierra 1500 models equipped with the 4.3L V6 engine (RPO LV3), 5.3L V8 engine (RPOs L82, L84) or 6.2L V8 engine (RPO L87). Engine conditions may include an illuminated Check Engine light, no start, engine runs rough, erratic gauge operation, erratic transmission shifting, and several blown fuses. There also may be a number of powertrain and communication DTCs set.

The engine performance conditions may be caused by the engine wiring harness chafing on the Engine Control Module (ECM) mounting bracket. (Fig. 18)

Fig. 18

The contact with the edge of the ECM mounting bracket (Fig. 19) may be causing damage to a number of circuits in the wiring harness, resulting in the wide variety of different symptoms that may occur.

Fig. 19

Inspect the engine harness in the area around the ECM mounting bracket. If harness damage is found (Fig. 20), repair the damaged wiring following the appropriate Service Information wire to wire repair procedures. Once repaired, protect the engine wiring harness using Woven Polyester (PET) Electrical/Anti-Abrasive Tape.

Fig. 20

– Thanks to Richard Renshaw

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