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 P182A: Internal Mode Switch A Circuit Low VoltageDTC 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 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 |
|---|---|---|---|
TR Signal A | P1820, P1825, P1915 | P1825, P1915 | -- |
TR Signal B | P1825, P1915 | P1822, P1825, P1915 | -- |
TR Signal C | P1825, P1915 | P1826, P1825, P1915 | -- |
TR Signal P | P1823, P1825, P1915 | P1825, P1915 | -- |
Circuit/System Description
The internal module switch (IMS) is a sliding contact switch attached to the selector detent inside the transmission side cover. The 4 inputs to the transmission control module (TCM) indicate the transmission range selector position. The input voltage level at the TCM is high, B+, when the IMS is open and low, 0 volts, when the switch is closed to ground. The 4 input parameters represented are Signals A, B, C and P - Parity.
Conditions for Running the DTC
P182A, P182C, P182D, P182E
| • | No engine torque signal DTC P2637. |
| • | The engine run time is greater than 5 seconds. |
| • | The engine torque is 55-450 N·m (41-332 lb ft). |
| • | The IMS indicates Park/Neutral for at least 1 second. |
P182F
| • | No output speed sensor (OSS) DTCs P0722 or P0723. |
| • | No engine torque signal DTC P2637. |
| • | Vehicle speed is greater than 16 km/h (10 mph). |
| • | The engine torque is greater than 50 N·m (37 lb ft). |
| • | The IMS indicates Park/Neutral for at least 1 second. |
| • | DTC P1826 has not passed during the current ignition cycle. |
| • | The gear ratio is within one of the following ranges: |
| - | 3.33:1 to 3.50:1 for first gear |
| - | 2.16:1 to 2.27:1 for second gear |
| - | 1.56:1 to 1.64:1 for third gear |
| - | 0.98:1 to 1.03:1 for fourth gear |
P1915
| • | The engine is cranking for more than 2.5 seconds. |
| • | The engine speed is greater than 500 RPM. |
| • | 1st gear request for 7 minutes. |
Conditions for Setting the DTC
P182A, P182C, P182D
| • | The switch indicates PARK for 1 second, then; |
| • | The switch indicates a transitional state for greater than 8 seconds. |
P182E
The TCM detects an invalid switch range for 8 seconds.
P182F
The TCM detects Signal C is high for 8 seconds.
P1915
The IMS Range is not equal to Park/Neutral for greater than 2 seconds.
Action Taken When the DTC Sets
| • | DTCs P182A, P182C, P182D, P182E, P182F, P1915 are Type B DTCs. |
| • | The TCM commands maximum line pressure. |
| • | The TCM freezes transmission adaptive functions. |
| • | The TCM assumes a D4 shift pattern. |
Conditions for Clearing the DTC
DTCs P182A, P182C, P182D, P182E, P182F, P1915 are Type B DTCs.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics
Connector End View Reference
Description and Operation
Transmission General Information
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Transmission Control Module Scan Tool Information
Special Tools
| • | J 35616 GM-Approved Terminal Test Kit |
| • | J 44152 Jumper Harness (20 Pins) |
Circuit/System Verification
Start and idle the engine. Using the scan tool, observe the IMS A/B/C/P parameter. The scan tool should display LOW/HI/HI/LOW. Move the gear selector through all ranges and ensure the IMS A/B/C/P parameter matches the gear selector for each selected range.
Circuit/System Testing
- Using the scan tool, does the IMS A/B/C/P parameter display HI/HI/HI/HI for each range selected.
- Turn OFF the ignition. Disconnect the automatic transmission inline 20-way connector. Additional DTCs may set. Turn ON the ignition, with the engine OFF. Observe the IMS A/B/C/P parameter on the scan tool. The parameter should display HI/HI.
- Turn OFF the ignition. Install the J 44152 jumper harness (20 pins), on the engine side of the automatic transmission inline 20-way connector. Turn ON the ignition, with the engine OFF. Using the DMM and the J 35616 GM terminal test kit, measure the voltage at each of the TR signal circuits at the J 44152 .
- Turn OFF the ignition. Install the J 44152 on the transmission side of the automatic transmission inline 20-way connector. Measure the resistance for each TR signal circuit between the J 44152 circuit and the transmission case. The resistance should be greater than 10 ohms.
- Connect the automatic transmission 20-way inline connector. Turn ON the ignition, with the engine OFF. Place the range selector in D3. Observe the IMS A/B/C/P parameter on the scan tool. The IMS A/B/C/P parameter should display LOW/LOW/LOW/LOW.
- If all circuits and connections test normal, test or replace the IMS switch.
| ⇒ | If the IMS A/B/C/P parameter displays HI/HI/HI/HI for each range selected, repair the open in the IMS ground circuit. |
| ⇒ | If the IMS A/B/C/P parameter does not display HI/HI/HI/HI, repair the short to ground in the TR signal circuit that displayed LOW between the TCM and the automatic transmission 20-way inline connector. |
| ⇒ | If the voltage is less than battery voltage, test the affected TR signal for an open between the TCM and the automatic transmission 20-way inline connector. |
| ⇒ | If the resistance is less than 10 ohms, test the affected TR signal for a short to ground between the automatic transmission 20-way inline connector and the IMS switch. |
| ⇒ | If any of the TR signal circuits do not display LOW when the range selector is placed in D3, test the affected TR signal for an open or high resistance between the automatic transmission 20-way inline connector and the IMS switch. |
Component Testing
- Disconnect the automatic transmission inline 20-way connector. Install the J 44152 on the transmission side of the connector and use J 35616 . Referencing Transmission Internal Mode Switch Logic , test for continuity between the IMS ground circuit and each TR signal circuit at the transmission side of the automatic transmission inline 20-way connector, when Transmission Internal Mode Switch Logic indicates the signal circuit should be LOW.
- Measure the resistance between each of the TR signal circuits and the transmission case. The resistance should be greater than 10 ohms.
- If all circuits and connections test normal and the IMS switch tests normal, replace the TCM switch.
| ⇒ | If any TR signal circuits do not display continuity when the table indicates it should be LOW, test the affected TR signal circuit for an open or high resistance between the automatic transmission inline 20-way connector and the IMS switch. |
| ⇒ | If any of the TR signal circuits display less than 10 ohms, test the affected TR signal for a short to ground. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
Control Module References for TCM replacement, setup, and programming
