P1825
DTC P1825, P182E, or P1915
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (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
Typical Scan Tool Data
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 500 RPM or greater for 5 seconds.
* The ignition voltage is between 9.0 volts and 18.0 volts.
* Either the C1234 or CB26 pressure switch is pressurized.
* DTC P0101, P0102, P0103, P0121, P0122, P0123, P0722, P0723, or P182E is not set.
P1915
* DTC P0722, P0723, or P1915 is not set.
* The transmission output shaft speed is less than 90 RPM or less.
* The ignition voltage is between 9.0 volts and 18.0 volts.
* The IMS does not indicate park or neutral.
Conditions for Setting the DTC
P1825 or P182E
The IMS does not indicate a valid Park, Reverse, Neutral, or Drive Range position for 7 seconds.
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.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics (6T30/6T40/6T45/6T50 - Automatic Transmission)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
Description and Operation
* Transmission General Description (Transmission General Description)
* Transmission Component and System Description (Transmission Component and System Description)
* Electronic Component Description (Electronic Component Description) for manual shift detent lever with shaft position switch assembly
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Special Tools
DT-48616-10 - Adapter Harness
For equivalent regional tools, refer to Special Tools (6T30/6T40/6T45/6T50 - Automatic Transmission).
Circuit/System Verification
1. Ignition ON, engine OFF, observe the scan tool IMS A/B/C/P parameter while moving the gear shift lever from Park, to Reverse and through all the ranges. The parameter should match each range that is selected. Refer to Transmission Internal Mode Switch Logic (Transmission Internal Mode Switch Logic).
2. Observe the scan tool engine control module (ECM) PNP Switch parameter while moving the gear shift lever from Park, to Reverse and through all the ranges. The parameter should display Park/Neutral in the Park and Neutral positions, and In Gear in Reverse and Drive.
• If not the expected results, refer to DTC P0850-P0852 (6T30/6T40/6T45/6T50 - Automatic Transmission).
3. After performing the above steps, verify that the DTC does not reset by operating the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions you observe from the Freeze Frame/Failure Records data. If the vehicle passes the Circuit/System Verification procedure, then STOP. Do not perform the Circuit/System Testing or Component Testing as this may result in an unnecessary part replacement. Refer to Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections).
Circuit/System Testing
Note: You must perform the Circuit/System Verification first.
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 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 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 F. 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 B to terminal F
* Switch Signal B: terminal C to terminal F
* Switch Signal C: terminal D to terminal F
* Switch Signal P: terminal E to terminal F
• If not the specified value, replace the control solenoid valve assembly.
6. If all circuits test normal, replace the IMS.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
Note: Before replacing the TCM, perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection (Control Solenoid Valve and Transmission Control Module Assembly Inspection).
* Refer to Control Module References (Programming and Relearning) for control solenoid valve assembly replacement, setup, and programming.
* Perform the Service Fast Learn Adapts (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 (6T30/6T40/6T45/6T50 - Automatic Transmission).