Diagnostic Aids

WARNING: This page does not describe the selected car, but rather 14 other vehicles, including the 1998 GMC Savana Special, 1998 GMC Savana Camper Special, 1998 GMC Savana, 1998 Chevrolet RV Cutaway, and 1998 Chevrolet Cutaway. However, it is still accessible from the selected car via links, so may be relevant.

Inspect wiring for poor connections at VCM and at transmission 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Inspect for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change. First diagnose and clear any engine and TP sensor DTCs that are present, then inspect for any transmission DTCs that may have reset. DTC P1810 can be falsely set during fluid fill procedure. After refilling fluid, cycle key off, then start and run engine for 20 seconds. Turn ignition off and allow VCM to power down, then restart vehicle. DTC P1810 can be falsely set by low pump pressure or a stuck pressure regulator. DTC P1810 can be set by a slipping forward clutch assembly. VCM may see a 2.08:1 ratio (Reverse) when manual valve position is "D4".