The tire pressure warning lamp may be illuminated and the tire pressure learn for one or both front tires may not be able to be completed on some 2025-2026 Equinox and Terrain models. (Fig. 5) Tire Pressure Monitor sensor DTCs C1171, C1172, C1173 and/or C1174 also may be set.
Fig. 5
The cause of these conditions may be the connector at the Telematic Control Module (OnStar). The module may have a poor connection due to the wiring pulling on the connector. (Fig. 6)
Fig. 6
If the sensors cannot be learned using the EL-52545 Tire Pressure Monitor Sensor and RF Diagnostic Tool (preferred method) or El-50448 Tire Pressure Monitor Sensor Activation Tool (alternative method), do not replace the Tire Pressure Monitor sensors.
TIP: These conditions also can cause remote key fob-related issues when accompanied by one or more of the DTCs listed above. If there are intermittent key fob issues and TPM codes set, it is possible this procedure will resolve the key fob concerns too.
Connector Tension
Begin diagnosis by following the procedures in the appropriate Service Information for each DTC. If the repairs do not correct the issue, inspect the Telematic Control Module connector and lessen the tension on the connector by pulling the wiring through the harness retainers.
To access the Telematic Control Module connector, open the liftgate and gently pull down the headliner at the rear of the vehicle.
At the right-side retainer, move the connector wiring to the left through the wiring retainer until the retainer is on the right end of the harness tape. (Fig. 7) It may be necessary to remove the retainer from the body hole to work through the harness.
Fig. 7
At the left-side retainer, perform the same procedure, moving the wiring to the left until the retainer is at the right end of the harness tape. (Fig. 8) Remove the retainer from the body hole if needed. Reinstall the retainers if removed.
Fig. 8
Once the wiring is repositioned, confirm that the connector is seated properly and is not being pulled out by the wiring harness tension.
For additional information, including build dates, refer to Bulletin #26-NA-070.
– Thanks to Rob Smith
