Multiple Electrical Conditions, Illuminated Instrument Cluster Warning Lamps, and DIC Messages

There may be a number of electrical conditions present on some 2018-2020 Equinox and Terrain models. The conditions may include illuminated warning lamps on the instrument cluster, a Service Transmission message and StabiliTrak message on the Driver Information Center (DIC), a parking brake that remains on causing no vehicle movement, a transmission that will not shift, no Reverse gear, and a vibration on rough roads or on acceleration or deceleration (torque related).

Any of the following DTCs may be set: P057D, P057E, P0658, P0700, P073D, P07E4, P16F4, P175F, P1778, P1789, P2760, U0073, U0101, and/or U0121.

These conditions may be the result of the engine wiring harness contacting the transmission mounting bracket or a transmission control valve body cover stud.

TIP: The engine wiring harness is a multi-wire bundled harness and, depending on which wire is damaged, can set a variety of DTCs. Not all of the identified conditions may be present, but several of the conditions may be caused by one of the wires in the harness being chafed or cut. Due to the cause of the condition, and the positions of the wires in the harness, it is unlikely that more than one circuit and/or fuse will be affected by the condition.


Wiring Harness

Inspect the wiring harness for proper routing and circuit 6387 for any damaged wiring. (Fig. 15)


Fig. 15


Damage may be found at circuit 6387 TCM high side driver. (Fig. 16)


Fig. 16


In addition, check that the wiring harness retainer is properly installed into the bracket (shown not installed). (Fig. 17)


Fig. 17


Repair any damaged wires according to the proper Service Information wiring repair procedures.


Transmission Valve Cover Stud

Inspect the wiring harness conduit and wires for chafing around the #2, 5 and/or 9 stud of the transmission control valve body cover. (Fig. 18)


Fig. 18


At the point of contact, remove the wrap to check for any damaged wiring. (Fig. 19) Repair the damaged wires according to the proper Service Information wiring repair procedures.


Fig. 19


Use Woven Polyester Electrical Tape (PET) to tape all contact points of the engine wiring harness, ensuring that the tape is applied in a double layer extending along the harness past the splice sleeves

Refer to Bulletin #19-NA-181 for additional information.


– Thanks to Rob Smith

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