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P0816



DTC P0815, P0816, or P0826

Diagnostic Instructions

* Perform theDiagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* ReviewStrategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) 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




Diagnostic Fault Information






Circuit/System Description

The drivers shift request (DSR), also known as the TAP Shift, allows the driver to manually shift gears by pressing the plus (+) or minus (-) buttons and select the desired range of gears for current driving conditions by using the DSR shift switch located on the automatic transmission gear shift lever. Pushing the plus (+) switch will command an upshift and pushing the minus (-) switch will command a downshift. A 12 V reference voltage flows from the body control module (BCM) through the DSR switch resistor array to the BCM. The DSR shift system is activated when the gear selector is in the Manual (M) position. The DSR system is deactivated in all other range positions.


Conditions for Running the DTC

P0815, P0816, or P0826

The engine speed is between 200-7500 RPM for at least 5 seconds.


P0815 or P0816
* No DTCs P0826 or P0708.
* The time since the last gear selector range change is greater than 6 seconds.



Conditions for Setting the DTC

P0815

The BCM detects an upshift request for 3 seconds in PARK, REVERSE, NEUTRAL, or D1 and for 600 seconds in PARK, REVERSE, NEUTRAL, D2, or D1.

P0816

The BCM detects a downshift request for 3 seconds in PARK, REVERSE, NEUTRAL, or D1 and for 600 seconds in PARK, REVERSE, NEUTRAL, D2, or D1.

P0826

The BCM detects an invalid voltage on the TAP up/down signal circuit for 5 seconds.


Action Taken When the DTC Sets

* DTCs P0815, P0816, P0826, and P1876 are Type C DTCs.
* The BCM disables TAP shift operation.



Conditions for Clearing the DTC

DTCs P0815, P0816, P0826, and P1876 are Type C DTCs.


Reference Information
Schematic Reference

Automatic Transmission Controls Schematics (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

* Transmission General Description (Transmission General Description)
* Transmission Component and System Description (Transmission Component and System Description)
* Electronic Component Description (Electronic Component Description)

Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information


Circuit/System Verification

1. Ignition ON, verify with a scan tool the Tap Up/Down Switch parameter displays On.
2. Ignition ON, cycle the automatic transmission manual shift switch while observing the Tap Up/Down Switch parameter. The parameter should change to Up when the plus (+) switch is selected, and Down when the minus (-) switch is selected.
3. Operate the vehicle within the Conditions for Running the DTC to verify that the DTC not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.



Circuit/System Testing

1. Ignition OFF, disconnect the automatic transmission shift lever harness connector.
2. Ignition ON, verify with a scan tool the Tap Up/Down Switch parameter displays Off.

• If not the specified value, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM.

3. Ignition ON, test for greater than 11 V between the ignition voltage circuit terminal D and ground.

• If less than the specified value, test the ignition voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

4. Ignition OFF, test for 6.6-7.0 K ohms between terminal C and terminal D of the automatic transmission shift lever harness connector. Also, test for 3.7-4.2 K ohms when selecting the minus (-) switch, and 1.7-2.0 K ohms when selecting the plus (+) switch.

• If not within the specified values, replace the automatic transmission lever.


• If the specified values are normal, test the signal circuit for a short to ground or an open/high resistance. If circuit tests normal, replace the BCM.




Repair Instructions

Perform theDiagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Shift Lever Replacement (Shift Lever Replacement) for RSM shift switch replacement.
* Control Module References (Programming and Relearning) for BCM replacement, setup, and programming.



Repair Verification

If another DTC is present, refer toDiagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code Descriptions) and perform the appropriate diagnostic procedure.

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