Diagnostic Aids

WARNING: This page is about a different car, the 2002 GMC Yukon XL, 2002 GMC Sierra, 2002 Chevrolet Suburban, and 2002 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Inspect wiring for poor connections at PCM and at transmission in-line 20-way harness connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wires that could short to bare metal or other wiring. Inspect for wires broken inside their insulation. If diagnosing for intermittent short or open conditions, move wiring harness while observing scan tool for value changes.

See TFP MANUAL VALVE POSITION SWITCH LOGIC table under DESCRIPTION & OPERATION for the normal range signals and the illegal combinations.

DTC P1810 can be set falsely by low pump pressure, a stuck pressure regulator, or unit fill from overhaul and pan removal.

DTC P1810 can be set by a slipping forward clutch. It may allow the PCM to see a 2.08:1 ratio (Reverse) when the manual valve position is indicated as D4.

DTC P1810 defaults to an elevated line pressure condition which may result in TCC partial apply. This may induce idle surge and engine stall.