GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2009 🢒 G6 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC P1825, P182E, or P1915

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 Does Not Indicate Park/Neutral (P/N) During Start

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

Normal Range

Short to Ground

Open

Short to Voltage

Operating Conditions: Ignition ON, range selector in Park

Transmission Range Switch Signal A

LOW

LOW

HI

HI

Transmission Range Switch Signal B

HI

LOW

HI

HI

Transmission Range Switch Signal C

HI

LOW

HI

HI

Transmission Range Switch Signal P

LOW

LOW

HI

HI

HI = 12 volts

LOW = 0 volts

Circuit/System Description

The internal mode switch (IMS) assembly is a sliding contact switch attached to the control valve body inside 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 9.0 volts and 19.0 volts.
    • Either the C1234 or CB26 pressure switch is pressurized.

P1915

    • No OSS DTCs P0722 or P0723.
    • The transmission output shaft speed is less than 90 RPM or less.
    • The ignition voltage is between 6.0 volts and 18.0 volts.

Conditions for Setting the DTC

P1825 or P182E

Any one of the following Fail Cases occur:

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 at least 0.225 seconds 15 or more times.

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 at lease 0.225 seconds 15 or more times.

Fail Case 3

The TFP Switch 3 or TFP Switch 4 is pressurized and the IMS indicates a Neutral/Drive 6 transitional state for at least 0.225 seconds 15 or more times.

Fail Case 4

The IMS indicates an invalid range or the IMS state and the ECM Park/Neutral Signal do not match for 2.0 seconds or greater.

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 at least 0.225 seconds 15 or more times.

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 0.10 seconds.
    • The engine speed is 50-480 RPM for more than 0.07 seconds.
    • The engine speed is greater than 525 RPM for more than 1.25 seconds.
    • The transmission input shaft speed is 100 RPM or greater.

Action Taken When the DTC Sets
    • DTCs P1825 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 3rd gear if the current gear is 1st, 2nd, or 3rd; or 5th gear if the current gear is 4th, 5th, or 6th gear.
    • The TCM forces the TCC OFF.
    • The TCM inhibits the Tap Up / Tap Down function.

Conditions for Clearing the DTC

DTCs P1825, P182E and P1915 are Type A DTCs.

Diagnostic Aids

Disconnecting the 14-way connector from the transmission will disable TCM communications. Use the Internal Mode Switch Logic table to compare scan tool reading with the transmission fluid pressure (TFP) switch. TFP switch states should correspond to the correct gear positions.

Reference Information

Schematic Reference

Automatic Transmission Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

    •  Transmission General Description
    •  Transmission Component and System 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

    Note: 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.
    5. ⇒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.
    6. • 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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

       Note: Before replacing the TCM, perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection.

    • Refer to Control Module References for control solenoid (w/body and TCM) valve assembly replacement, setup, and programming.
    • Perform the Service Fast Learn Adapts following all transmission related repairs.
    • For internal mode switch (IMS) replacement - perform the Manual Shift Detent Lever with Shaft Position Switch Assembly Replacement.