P1915
DTC P1825 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 P1915
- Internal Mode Switch Start/Wrong Range
Diagnostic Fault Information
Typical Scan Tool Data
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
* The engine speed is greater than 500 RPM for 5 seconds.
* The ignition voltage is between 8.6 volts and 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 volts and 19.0 volts.
Conditions for Setting the DTC
P1825
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 8 seconds or more.
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.
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.
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.
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.
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 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 3.25 seconds.
* The transmission input shaft speed is 200 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 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 and P1915 are Type A DTCs.
Diagnostic Aids
The IMS is part of a wire harness, which connects electrically to the control solenoid (w/body and TCM) valve assembly and is serviced separately from the control solenoid (w/body and TCM) valve assembly. Inspect the IMS, harness, connector, and control solenoid (w/body and TCM) valve assembly pins for metallic debris. Use the J 35616 GM-approved terminal test kit for any test that requires probing the control solenoid (w/body and TCM) valve assembly harness connector or a component harness connector.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views
Description and Operation
* Transmission General Description (Transmission General Description)
* Refer to Electronic Component 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
1. Ignition OFF, remove the control valve body cover. Refer to Control Valve Body Cover Replacement (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 terminal at the control solenoid (w/body and TCM) valve assembly and ground. The appropriate scan tool IMS A/B/C/P parameter should display LOW when the terminal is connected to ground.
• If not the specified value, replace the control solenoid (w/body and TCM) valve assembly.
6. If all components test normal, replace the IMS.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Important:
* Perform the Service Fast Learn Adapts (Programming and Relearning) following all transmission related repairs.
* Perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection (Control Solenoid Valve and Transmission Control Module Assembly Inspection) before replacing the TCM.
* Manual Shift Detent Lever with Shaft Position Switch Assembly and Park Pawl Actuator Removal (Overhaul) and Manual Shift Detent Lever with Shaft Position Switch Assembly and Park Pawl Actuator Installation (Overhaul) .
* Refer to Control Module References for control solenoid (w/body and TCM) valve assembly replacement, setup, and programming.