2ML70 - Automatic Transmission
DTC P1824, P182A-P182F, P1838, or P1839
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 Instructionsprovides an overview of each diagnostic category.
DTC Descriptors
DTC P1824
- Internal Mode Switch P Circuit High Voltage
DTC P182A
- Internal Mode Switch A Circuit Low Voltage
DTC P182B
- Internal Mode Switch B Circuit Low Voltage
DTC P182C
- Internal Mode Switch B Circuit High Voltage
DTC P182D
- Internal Mode Switch P Circuit Low Voltage
DTC P182E
- Internal Mode Switch-Invalid Range
DTC P182F
- Internal Mode Switch C Circuit High Voltage
DTC P1838
- Internal Mode Switch A Circuit High Voltage
DTC P1839
- Internal Mode Switch C Circuit Low Voltage
Diagnostic Fault Information
Typical Scan Tool Data
Transmission Internal Mode Switch Logic
Circuit/System Description
The automatic transmission manual shift shaft position switch assembly, also called the transmission internal mode switch assembly, is a dual sliding contact switch attached to the control valve body within the transmission. The 9 outputs from the switch indicate which position is selected by the transmission manual shaft. Four outputs (A, B, C, P) are range selection inputs to the transmission control module (TCM). Five outputs (R1, R2, D1, D2, S) are direction selection inputs to the hybrid powertrain control module. The input voltage at the modules 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 Range and IMS Direction. The IMS Range input parameters represented are transmission range signal A, signal B, signal C, and signal P. The IMS Direction input parameters represented are transmission direction signal R1, signal R2, signal D1, signal D2, and signal Start.
Conditions for Running the DTC
* No OSS DTCs P0722 or P077B.
* The system voltage is 11-18 V.
P182E
* The engine run time is greater than 5 seconds.
* The system voltage is 11-18 V.
* The vehicle speed is less than 200 km/h (124 mph) for 5 seconds.
Conditions for Setting the DTC
Any one or more of the following conditions:
* The IMS signal circuit A, B, or P are Low in Park for greater than 8 seconds.
* The IMS signal circuit A is Low in D for 8 seconds.
* The IMS signal circuit C is High in D for 8 seconds.
* The TCM detects an invalid range from the IMS for 3.25 seconds.
* The IMS signal circuit C is high in D for greater than 8 seconds.
* Park/Neutral Switch equals P/N and the IMS state is not Park or Neutral, or the Park/Neutral switch is not Park or Neutral and the IMS state equals Park or Neutral for 4 seconds.
* Or the automatic transmission manual shift shaft position switch assembly indicates a transitional state for 8 seconds.
Action Taken When the DTC Sets
* The TCM commands maximum line pressure.
* The TCM turn OFF all solenoids.
* The TCM freezes transmission adaptive functions.
* The TCM defaults the transmission to 3rd gear if the current gear is 1st or 2nd gear, or 3rd gear if the current gear is 4th gear.
Conditions for Clearing the DTC
DTCs P1824, P182A-P182F, P1838, and P1839 are Type B DTCs.
Diagnostic Aids
The transmission internal mode switch connects electrically to the control solenoid valve assembly and is serviced separately from the control solenoid valve assembly. Inspect the transmission internal mode switch, harness, connector, and control solenoid valve assembly pins for metallic debris. Use a terminal test kit for any test that requires probing the control solenoid valve assembly harness connector or a component harness connector. The transmission internal mode switch assembly can be damaged by currents exceeding 2 mA. Test the transmission internal mode switch assembly for an open condition whenever a short to voltage condition is observed.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics 2ML70 - Automatic Transmission
Connector End View Reference
Component Connector End Views Connector End Views By Name
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 Relearningfor scan tool information.
Circuit/System Verification
Test for the correct operation of the S2 transmission manual shift switch. Refer to Transmission Internal Mode Switch Logic Transmission Internal Mode Switch Logic.
If the S2 transmission manual shift switch operation matches the S2 transmission manual shift switch logic table, the system if functioning normally.
Circuit/System Testing
Note: Damage to the TCM may occur if the X1 16 way harness connector is disconnected before the X176 24 way connector or if the X1 16 way harness connector is connected after the X176 24 way connector.
1. Disconnect the X2 B15 transmission internal mode switch harness connector at the Q8 control solenoid valve assembly. Ignition ON. The scan tool IMS A/B/C/P parameter should display HI for all 4 signal circuits.
• If a signal circuit displays LOW, replace the Q8 control solenoid valve assembly.
2. Connect a 3-amp fused jumper wire between each transmission range signal circuit at the Q8 control solenoid valve assembly and ground. With a scan tool, ensure that each signal circuit displays LOW when connected to ground.
• If a signal circuit remains HI when connected to ground, replace the Q8 control solenoid valve assembly.
3. Connect the B15 transmission internal mode switch harness connector to the Q8 control solenoid valve assembly. Disconnect the B15 transmission internal mode switch connector. The scan tool B15 transmission internal mode switch A/B/C/P parameter should display HI for all 4 signal circuits.
• If a signal circuit displays LOW, replace the B15 transmission internal mode switch jumper harness.
4. Connect a 3-amp fused jumper wire between each transmission range signal circuit at the B15 transmission internal mode switch connector harness and ground. With a scan tool, ensure that each signal circuit displays LOW when connected to ground.
• If a signal circuit remains HI when connected to ground, replace the B15 transmission internal mode switch harness.
• If a signal circuit other than the circuit being grounded displays LOW, replace the B15 transmission internal mode switch harness.
• If all circuits test normal, replace the B15 transmission internal mode switch.
Component Testing
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
Note: Perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection Control Solenoid Valve and Transmission Control Module Assembly Inspection for the following components before replacing the components.
* Manual Shift Shaft Position Switch Replacement 2ML70 - Automatic Transmissionfor Transmission Internal Mode Switch replacement
* Wiring Harness Replacement Wiring Harness Replacementfor Automatic Transmission Control Wiring Harness Extension Harness Assembly replacement
* Control Module References Programming and Relearningfor Control Solenoid Valve Assembly replacement, programming and setup