For 1990-2009 cars only
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 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 | P182A, P182E, P1915 | P182E, P1915 | -- |
TR Signal B | P182E, P1915 | P182C, P182E, P1915 | -- |
TR Signal C | P182E, P1915 | P182F, P182E, P1915 | -- |
TR Signal P | P182D, P182E, P1915 | P182E, P1915 | -- |
Gear Selector Position | A | B | C | P | ||||
|---|---|---|---|---|---|---|---|---|
Park | LOW | HI | HI | LOW | ||||
Park/Reverse | LOW | HI | HI | HI | ||||
Reverse | LOW | LOW | HI | HI | ||||
Reverse/Neutral | HI | LOW | HI | HI | ||||
Neutral | HI | LOW | HI | LOW | ||||
Neutral/Drive 5 | HI | LOW | LOW | LOW | ||||
Drive 5 | HI | LOW | LOW | HI | ||||
Drive 5/Drive 4 | LOW | LOW | LOW | HI | ||||
Drive 4 | LOW | LOW | LOW | LOW | ||||
Drive 4/Drive 3 | LOW | HI | LOW | LOW | ||||
Drive 3 | LOW | HI | LOW | HI | ||||
Drive 3/Drive 2 | HI | HI | LOW | HI | ||||
Drive 2 | HI | HI | LOW | LOW | ||||
Open | HI | HI | HI | HI | ||||
Invalid | HI | HI | HI | LOW | ||||
| ||||||||
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 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
| • | No engine torque signal DTC P2637. |
| • | The engine run time is greater than 5 seconds. |
| • | The engine torque is greater than 55-450 N·m (41-332 lb ft). |
P182D
| • | No engine torque signal DTC P2637. |
| • | The engine run time is greater than 5 seconds. |
| • | The engine torque is greater than 25 N·m (18 lb ft). |
P182E
The engine is running for 5 seconds.
P182F
| • | No OSS DTCs P0722 or P0723. |
| • | No engine torque signal DTC P2637. |
| • | Vehicle speed is greater than 8 km/h (5 mph). |
| • | Engine torque is greater than 20 N·m (15 lb ft). |
| • | DTC P182F 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 |
| - | 0.73:1 to 0.77:1 for fifth gear |
P1915
| • | No OSS DTC P0722 or P0723. |
| • | The transmission output shaft speed is less than 100 RPM. |
Conditions for Setting the DTC
P182A, P182C
| • | The switch indicates PARK for 1 second, then; |
| • | The switch indicates a transitional state for greater than 4 seconds. |
P182D
| • | The switch indicates PARK for 1 second, then; |
| • | The switch indicates a transitional state for greater than 5 seconds. |
P182E
The TCM detects an invalid switch range for 5 seconds.
P182F
The TCM detects Signal C is high, while the gear ratio indicates first, second, third, fourth, or fifth gear for 3 seconds.
P1915
The manual shift shaft switch assembly indicates a transitional state during the following sequence:
| • | The engine speed is 60 RPM or less for 0.25 second or greater. |
| • | The engine speed is 81-625 RPM for 0.15 second or greater. |
| • | The engine speed is 651 RPM or greater for 1.5 seconds or greater. |
| • | The transmission input shaft speed is 200 RPM or greater for 1.5 seconds or greater. |
Action Taken When the DTC Sets
| • | DTCs P182A, P182C, P182D, P182E, P182F and P1915 are Type B DTCs. |
| • | The TCM commands maximum line pressure. |
| • | The TCM freezes transmission adaptive functions. |
| • | The TCM assumes a D5 shift pattern. |
Conditions for Clearing the DTC
DTCs P182A, P182C, P182D, P182E, P182F and P1915 are Type B DTCs.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics
Connector End View Reference
Description and Operation
Transmission General Description
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 45681 Jumper Harness |
| For equivalent regional tools, refer to Special Tools. |
Circuit/System Verification
- Perform the Transmission Fluid Check to verify correct fluid level and condition. The transmission fluid level should be within the crosshatch band and the transmission fluid should be red or dark brown.
- Engine idling, observe the scan tool IMS A/B/C/P parameter while moving the gear shift lever from Park, to Reverse and through all the gear ranges and compare to the Transmission Fluid Pressure Manual Valve Position Switch Logic table. The parameter should match each gear range that is selected.
- Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
| ⇒ | If the transmission fluid is low or discolored, refer to Automatic Transmission Fluid and Filter Replacement. |
Circuit/System Testing
- Ignition OFF, disconnect the automatic transmission (AT) inline 20-way connector at the transmission.
- Install the J 45681 harness on the engine side of the AT inline 20-way connector.
- Ignition ON, observe the IMS A/B/C/P parameter. The reading should 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 45681 harness , 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 test kit , measure the voltage at each of the TR signal circuits at the J 45681 harness .
- Turn OFF the ignition. Install the J 45681 harness on the transmission side of the automatic transmission inline 20-way connector. Measure the resistance for each TR signal circuit between the J 45681 harness 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 D4. 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.
Note: Additional DTCs may set when disconnecting the automatic transmission inline 20-way connector.
| ⇒ | If not the specified value, test the appropriate signal circuit for an open. If the circuits test normal, replace the TCM. |
| ⇒ | 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 D4, 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 45681 harness on the transmission side of the connector and use J 35616 test kit . 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 |
