The manual shift detent lever with shaft position switch assembly, or internal mode switch (IMS) assembly is a sliding contact switch attached to the control valve body within the transmission. The 4 inputs to the transmission control module (TCM) from the switch indicate which position is selected by the transmission manual shaft. The input voltage at the TCM is high when the switch is open and low when the switch is closed to ground. The state of each input is displayed on the scan tool as IMS. The IMS input parameters represented are transmission range signal A, Signal B, signal C, and signal P.

P1825 or P182E

P1915

P1825 or P182E - Fail Case 1

The TFP Switch 3 or TFP Switch 4 is pressurized with the commanded gear 1st locked and the IMS indicates a Drive 6/Drive 4 transitional state for 8 seconds or more.

P1825 or P182E - Fail Case 2

The TFP Switch 3 or TFP Switch 4 is pressurized and the IMS indicates a Drive 3/Drive 2 transitional state for 8 seconds or more.

P1825 or P182E - Fail Case 3

The TFP Switch 3 or TFP Switch 4 is pressurized and the IMS indicates a Neutral/Drive 6 transitional state for 1.25 seconds or more 6 times during the same ignition cycle.

P1825 or P182E - Fail Case 4

The IMS indicates an invalid range or the IMS state and the ECM Park/Neutral Signal do not match for 4 seconds or greater.

P1825 or P182E - Fail Case 5

The TFP Switch 3 or TFP Switch 4 is pressurized, the vehicle speed is 16 km/h (10 mph) or greater, and the IMS indicates a Reverse/Neutral transitional state for 3 seconds or greater.

P1825, P182E, or P1915

The manual shift shaft switch assembly does not indicate Park or Neutral during the following sequence:

DTCs P1825, P182E, and P1915 are Type A DTCs.

Schematic Reference

Automatic Transmission Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, engine OFF, observe the scan tool IMS parameter while moving the gear shift lever from Park, to Reverse and through all the ranges. The parameter should match each gear range that is selected.
2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Important: Do not connect an external voltage to any control solenoid (w/body and TCM) valve assembly terminal, and avoid the inadvertent shorting of terminals.

1. Ignition OFF, remove the control valve body cover. Refer to Control Valve Body Cover Replacement.
2. Connect the TCM harness connector.
3. Disconnect the IMS connector at the control solenoid (w/body and TCM) valve assembly.
4. Ignition ON, verify the scan tool IMS A/B/C/P parameter displays HI for all four signal circuits.

⇒	If not the specified value, replace the control solenoid (w/body and TCM) valve assembly.

5. Connect a 3-amp fused jumper wire between each transmission range signal circuit terminal listed below and the IMS ground circuit, terminal A. The appropriate scan tool IMS A/B/C/P parameter should display LOW when the terminal is connected to the IMS ground.

•	Switch Signal A terminal E

•	Switch Signal B terminal D

•	Switch Signal C terminal C

•	Switch Signal P terminal B

⇒	If not the specified value, replace the control solenoid (w/body and TCM) valve assembly.

6. If all circuits test normal, test or replace the IMS.

Important: 

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.