Range Selector Displays Incorrect Range

Range Selector Displays Incorrect Range

Circuit Description

The transmission internal mode switch (IMS) is a sliding contact switch attached to the selector detent inside the transmission side cover. The 4 inputs to the powertrain control module (PCM) indicate the transmission range selector position. 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 4 input parameters represented are Signal A, B, C and P, Parity. Refer to Transmission Internal Mode Switch Logic (Transmission Internal Mode Switch Logic).

Test Description

The numbers below refer to the step numbers on the diagnostic table.
2. HI values for all signals in all ranges indicates the ground circuit is OPEN.
3. With the 20-way connector disconnected, all signals should indicate HI.
5. If one circuit affects the other, this indicates a short between the 2 circuits.
11. This step tests the internal transmission harness. If no fault is found in the harness, the fault is in the switch.