P182B
DTC P1824, P182A-P182F, P1838, or P1839
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 Descriptor
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 internal mode switch (IMS) 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 control module (HCM). 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 P0723.
* The output speed sensor (OSS) is greater than 16 km/h (10 mph).
* The transmission output shaft speed is less than 90 RPM.
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 1 second.
* 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 and the engine torque is greater than 20 N•m (15 lb ft).
* 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 manual shift shaft switch assembly indicates a transitional state 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 greater than 250 RPM.
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 IMS 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 a 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. The IMS assembly can be damaged by currents exceeding 2 mA. Test the IMS assembly for an open condition whenever a short to voltage condition is observed.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views
Electrical Information Reference
* Circuit Testing
* Connector Repairs
* Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs
* High Voltage Disabling
* High Voltage Enabling
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
* Scan Tool Output Controls (Scan Tool Output Controls)
* Scan Tool Data List (Scan Tool Data List)
* Scan Tool Data Definitions (Scan Tool Data Definitions)
Circuit/System Verification
Test for the correct operation of the IMS. Refer to Transmission Internal Mode Switch Logic (Transmission Internal Mode Switch Logic) .
If the IMS operation matches the IMS logic table, the system if functioning normally.
Circuit/System Testing
1. Disconnect the IMS harness connector at the control solenoid (w/body and TCM) 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 control solenoid (w/body and TCM) valve assembly.
2. Connect a 3-amp fused jumper wire between each transmission range signal circuit at the control solenoid (w/body and TCM) 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, test the suspect IMS circuit for an open. If the circuit tests normal, replace the control solenoid (w/body and TCM) valve assembly.
3. Connect the IMS harness connector to the control solenoid (w/body and TCM) valve assembly. Disconnect the IMS connector. 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 IMS jumper harness.
4. Connect a 3-amp fused jumper wire between each transmission range signal circuit at the IMS 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 IMS harness.
• If a signal circuit other than the circuit being grounded displays LOW, replace the IMS harness.
• If all circuits test normal, replace the IMS.
Component Testing
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Important: Perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection (Control Solenoid Valve and TCM Assembly Solenoid Performance Test) for the following components before replacing the components.
1. IMS replacement. Refer to Manual Shift Shaft Position Switch Replacement (M99 - Automatic Transmission) .
2. Control solenoid (w/body and TCM) valve assembly replacement. Refer to Control Module References for replacement, setup, and programming.
3. A/trans control wiring harness extension harness assembly replacement. Refer to Wiring Harness Replacement (Wiring Harness Replacement) .