Diagnostic Aids

WARNING: This page is about a different car, the 2003 GMC Sonoma, 2003 GMC Jimmy, 2003 Chevrolet S10 Pickup, and 2003 Chevrolet Blazer. However, it is still accessible from the selected car via links, so may be relevant.

Refer to the TRANSMISSION FLUID PRESSURE (TFP) MANUAL VALVE POSITION SWITCH LOGIC table for the normal range signals and the invalid combinations. On the table, LOW is 0 volts, HI is ignition voltage.
Inspect the connectors at the PCM, the TFP manual valve position switch and all other circuit connecting points for an intermittent condition. Refer to TESTING FOR INTERMITTENT AND POOR CONNECTIONS in Wiring Systems.
Sediment in the valve body may cause improper operation of the TFP manual valve position switch. If sediment intrusion is suspected, clean the valve body and replace the TFP manual valve position switch.