For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptors

DTC P1825: Internal Mode Switch - Invalid Range
DTC P182E: Internal Mode Switch - Invalid Range
DTC P1915: Internal Mode Switch Start/Wrong Range

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Transmission Range Signal A | P1825, P182E | P1915 | P1915 | P1825, P182E, P1915
Transmission Range Signal B | P1915 | P1825, P182E | P1825, P182E | P1825, P182E, P1915
Transmission Range Signal C | P1915 | P1825, P182E | P1825, P182E | P1825, P182E, P1915
Transmission Range Signal P | P1825, P182E | P1915 | P1915 | P1825, P182E, P1915
Ground | -- | P1825, P182E | P1825, P182E | P1825, P182E, P1915

### Typical Scan Tool Data

#### IMS A/B/C/P

Circuit | Short to Ground | Open | Short to Voltage
--- | --- | --- | ---
Operating Conditions: Ignition ON, range selector in Park
Transmission Range Switch Signal A | LOW | HI | HI
Transmission Range Switch Signal B | LOW | HI | HI
Transmission Range Switch Signal C | LOW | HI | HI
Transmission Range Switch Signal P | LOW | HI | HI

### Circuit/System Description

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.

### Conditions for Running the DTC

#### P1825 or P182E

• | The engine speed is greater than 500 RPM for 5 seconds.

• | The ignition voltage is between 8.6-19.0 volts.

#### P1915

• | No OSS DTCs P0722 or P0723.

• | The transmission output shaft speed is 90 RPM or less.

• | The ignition voltage is between 8.6-19.0 volts.

### Conditions for Setting the DTC

#### 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:

• | The engine speed is less than 50 RPM for more than 0.25 second.

• | The engine speed is 50-480 RPM for more than 0.07 second.

• | The engine speed is greater than 525 RPM for more than 3.25 seconds.

• | The transmission input shaft speed is 200 RPM or greater.

### Action Taken When the DTC Sets

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

• | The TCM commands maximum line pressure.

• | The TCM turns OFF all solenoids.

• | The TCM freezes transmission adaptive functions.

• | The TCM defaults the transmission to third gear if the current gear is 1st, 2nd, or 3rd; or fifth gear if the current gear is 4th, 5th, or 6th gear.

### Conditions for Clearing the DTC

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

### Reference Information

#### Schematic Reference

Automatic Transmission Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

• | Transmission General Description

• | Electronic Component Description for manual shift detent lever with shaft position switch assembly

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

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.

### Circuit/System Testing

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.

### Repair Instructions

Important:

• | Perform the Service Fast Learn Adapts following all transmission related repairs.

• | Perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection before replacing the TCM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Manual Shift Detent Lever with Shaft Position Switch Assembly and Park Pawl Actuator Removal

• | Manual Shift Detent Lever with Shaft Position Switch Assembly and Park Pawl Actuator Installation

• | Control Module References for control solenoid (w/body and TCM) valve assembly replacement, setup, and programming