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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 214 (Automatic Transaxle Diagnosis - 4T65-E) >> Diagnostic Tests >> DTC P1825: Internal Mode Switch - Illegal Range >> Circuit Description

Circuit Description

WARNING: This page is about a different car, the 2003 Buick Regal and 2003 Buick Century. 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 gearshift lever. 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.

If the PCM detects an invalid transmission range with the engine running, then DTC P1825 sets. DTC P1825 is a type "C" DTC.