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Home >> Chevrolet >> 2001 >> Venture Base, Van Passenger >> Repair and Diagnosis >> External Pages >> Different car >> Section 484 (Automatic Transaxle Diagnosis, Service & Repair - 4T65-E) >> Diagnostic Information and Procedures >> DTC P1820: IMS Signal A Is Always Low >> Circuit Description

Circuit Description

WARNING: This page is about a different car, the 2003 Pontiac Aztek and 2003 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.

The transmission internal mode switch (IMS) is a sliding contact switch attached to the selector detent inside the transmission side cover. The four inputs to the PCM indicate the position of the transmission range selector. The input voltage level at the PCM is high, B+, when the IMS is open and low when the switch is closed to ground. The four input parameters represented are Signals A, B, C and P - Parity.

Refer to TRANSMISSION INTERNAL MODE SWITCH LOGIC  .

If the PCM detects that IMS Signal A is always low, then DTC P1820 sets. DTC P1820 is a type C DTC.

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