P0815
DTC P0815, P0816, P0826, or P1876
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 P0815
- Upshift Switch Circuit
DTC P0816
- Downshift Switch Circuit
DTC P0826
- Up and Down Shift Switch Circuit
DTC P1876
- Up and Down Shift Enable Switch Circuit Low Voltage
Diagnostic Fault Information
Circuit/System Description
The TAP Shift/Driver Shift Control (DSC) allows the driver to shift gears by using the TAP switches located on the automatic transmission shifter. Pushing forward on the shifter will command an upshift and pulling back will command a downshift. Ignition voltage flows from the ignition 3 fuse through the TAP Switch resistor array to the Transmission Control Module (TCM). The TAP system is activated when the gear shift lever is in the D position and moved over into the DSC gate area. When the shifter is moved over into the DSC gate area, the TAP enable switch is closed and completes the TAP enable circuit from the Instrument Panel Module (IPM) to ground.
Conditions for Running the DTC
P0815 or P0816
* No DTC P0826.
* No DTCs P1825 or P1915.
* The engine speed is between 500-7,500 rpm for at least 5 seconds.
* The time since the last gear selector range change is greater than 6 seconds.
P0826
* Ignition voltage is 8.6-19.0 volts.
* Engine speed is 500-6,500 rpm for at least 5 seconds.
P1876
* The following DTCs are not Fault Active or Test Fail this Key ON:
- DTC U0100.
- DTCs P0815, P0816, or P0826.
- DTCs P1825 or P1915.
* Ignition voltage is 8.6-19.0 volts.
* Engine speed is 500-6,500 RPM for at least 5 seconds.
Conditions for Setting the DTC
P0815
The TCM detects a Stuck ON upshift switch for 3 seconds in PARK, REVERSE, NEUTRAL, or D and for 600 seconds in PARK, REVERSE, NEUTRAL, or D.
P0816
The TCM detects a Stuck ON downshift switch for 3 seconds in PARK, REVERSE, NEUTRAL, or D and for 600 seconds in PARK, REVERSE, NEUTRAL, or D.
P0826
The TCM detects an invalid voltage on the TAP Up/Down Signal Circuit for 8 seconds.
P1876
The TCM detects a TAP Enable Switch request 3 times when not in D6 range for 2 seconds.
Action Taken When the DTC Sets
* DTCs P0815, P0816, P0826, and P1876 are Type C DTCs.
* The TCM disables TAP shift functions.
Conditions for Clearing the DTC
DTCs P0815, P0816, P0826, and P1876 are Type C DTCs.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics (Diagrams)
Connector End View Reference
* Component Connector End Views (Connector Views)
* Inline Harness Connector End Views (Connector Views)
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
Circuit/System Verification
1. Engine running, park brake applied, drive wheels chocked. Shift the transmission into the manual (M) position. Verify with a scan tool the following TCM parameters display the correct values:
* Drivers Shift Control - Inactive
* Drivers Shift Request - Inactive
2. Verify with a scan tool the following TCM parameters display the correct values when pushing the shift lever forward:
* Drivers Shift Control - Active
* Drivers Shift Request - Upshift
3. Verify with a scan tool the following TCM parameters display the correct values when pushing the shift lever rearward:
* Drivers Shift Control - Active
* Drivers Shift Request - Downshift
4. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
1. Ignition OFF, disconnect the automatic transmission shift lever harness connector.
2. Ignition OFF, test for less than 5 ohm between terminal G on the automatic transmission shift lever harness connector and ground at the battery negative post.
• If greater than the specified value, test the ground circuit for an open/high resistance.
3. Ignition ON, test for 11-13 volts between terminal B on the automatic transmission shift lever harness connector and ground at the battery negative post.
• If not within the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the IPM.
4. Ignition ON, test for 11-13 volts between terminal D on the automatic transmission shift lever harness connector and ground at the battery negative post.
• If not within the specified range, test the ignition voltage circuit for a short to ground or an open/high resistance.
5. Ignition OFF, shift the transmission into the manual position. Test for less than 5 ohm between terminal B and terminal G on the automatic transmission shift lever component connector.
• If greater than the specified value, replace the automatic transmission shift lever assembly.
6. Ignition OFF, test for 8.10-8.40 ohm between terminal D and terminal H on the automatic transmission shift lever component connector.
• If not within the specified range, replace the automatic transmission shift lever assembly.
7. Ignition OFF, test for 4.25-4.55 K ohm between terminal D and terminal H on the automatic transmission shift lever component connector, while pushing forward on the shift lever.
• If not within the specified range, replace the automatic transmission shift lever assembly.
8. Ignition OFF, test for 1.35-1.65 K ohm between terminal D and terminal H on the automatic transmission shift lever component connector, while pushing rearward on the shift lever.
• If not within the specified range, replace the automatic transmission shift lever assembly.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Replace the automatic transmission shift lever assembly. Refer to Transmission Control Replacement (Transmission Control Replacement).
* Replace the IPM. Refer to Control Module References (Programming and Relearning) for replacement, setup and programming.