Diagnostic Aids

WARNING: This page is about a different car, the 2003 GMC Yukon XL, 2003 Chevrolet Suburban, and 2003 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

Refer to Transmission Fluid Pressure (TFP) Manual Valve Position Switch Logic for the normal range signals and the illegal combinations.
DTC P1810 can set from low pump pressure, a stuck pressure regulator, or unit fill from overhaul and pan removal.
DTC P1810 can 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 partial TCC apply. This may produce an idle surge that could stall the engine.