Diagnostic Aids
WARNING: This page is about a different car, the 2008 GMC Yukon XL, 2008 GMC Yukon, 2008 Chevrolet Tahoe, 2008 Chevrolet Suburban, and 2008 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
- Inspect the connectors at the TCM, the AT ISS, and all other circuit connecting points for an intermittent condition. Refer to Testing for Intermittent Conditions and Poor Connections .
- Inspect the circuit wiring for an intermittent condition. Refer to Testing for Electrical Intermittents .
- Road test the vehicle while monitoring the Transmission ISS parameter on the scan tool. The Transmission ISS parameter should vary with engine speed changes and not abruptly drop out.
- Inspect for an open or shorted AT ISS wire.
- Inspect for a disconnected AT ISS connector.
- Inspect for a faulty AT ISS.