Several Driver Information Center warning messages may display on some 2019-2021 Blazers, including service brake, service steering, reduced power and other messages. The Check Engine MIL also may be illuminated along with any of the following DTCs: P0232, P023F, P0641, P0697, P2535, P129D, P12A6, P12A8, P2635, P3051, P3052, P3055, P3056, P305B, P035C, P035E, U0074, U0077, U0121, U0131, U0151, U0415, U0420, U18A2, U2502, and/or U2616.
These conditions may be caused by the wiring harness rubbing on the battery tray support bracket that secures the Transmission Control Module (TCM). (Fig. 21) Several circuits may be damaged in the harness, leading to codes and symptoms that will vary and may be intermittent depending on the affected circuits.
Fig. 21
If these conditions are found, inspect the wiring harness below the battery tray to determine if the routing of the harness is causing it to rub on the bracket for the TCM. (Fig. 22) Repair any damaged circuits and tape the harness.
Fig. 22
It will be necessary to remove the battery and battery tray to perform the repairs. (Fig. 23) Also check for any missing retainers for the wiring harness.
Fig. 23
Once repairs are completed, reroute or secure the harness to prevent further damage. It may be necessary to install a piece of heater hose or other conduit over the harness to prevent any chafing in the future.
Refer to Bulletin #PIT5847 for additional information.
– Thanks to Dave Goodrow
