Circuit/System Testing
WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect the X175 harness connector at the transmission.
- Ignition ON, engine OFF. Verify that a test lamp illuminates between the B+ circuit terminal L and ground.
- If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the TCM.
- Connect a test lamp between the control circuit terminal S and the B+ circuit terminal L.
- Command the Modulated Main Pres. Ctrl. Sol. ON and OFF with a scan tool and verify the Line PC Sol. Pressure Command parameter changes from 0 kPa (0 psi) to 1600 kPa (232 psi). The test lamp should turn ON and OFF when changing between the commanded states.
- If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the TCM.
- If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the TCM.
- Ignition OFF, install the X175 harness connector at the transmission.
- Remove the transmission oil pan. Refer to Oil Pan Replacement .
- Disconnect the Modulated Main Pressure Control Solenoid Valve connector.
- Connect a test lamp between the A and B terminals of the internal harness.
- Ignition ON, engine OFF, Command the Modulated Main Pres. Ctrl. Sol. ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
- If not the expected results, replace the transmission internal wiring harness. Refer to Wiring Harness Replacement .
- If circuits test normal, test or replace the Main Mod solenoid.