Diagnostic Instructions
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
The Diagnostic Fault Information table identifies possible circuit faults and the different circuit voltage associated with the fault.
Driver Shift Request
Circuit
| Short to Ground
| Open/High Resistance
| Short to Voltage
| Signal Performance
|
Normal Range = None
|
Tap Up/Tap Down Switch Signal Circuit
| 0 V
| 0 V
| 5-12 V
| --
|
Circuit/System Description
The Automatic Transmission Manual Shift System allows the driver to shift gears by using the paddle shift switches located on the steering wheel. The manual shift system is activated when the gear selector is placed in the S (Sport Mode) position. Pushing
forward on the paddle switch will command an upshift and pulling back on the switch will command a downshift. Ignition voltage from the ignition fuse through the paddle switch resistor array to the transmission control module (TCM).
In the S position, the Sport Mode enable switch is closed and this activates the system by completing the TAP enable signal circuit from the body control module (BCM) to ground. TAP system is deactivated in all other range positions.
Conditions for Running the DTC
P0815 or P0816
| • | 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 8.6-18.0 volts. |
| • | Engine speed is 500-7,500 RPM for at least 5 seconds. |
P1876
| • | The following DTCs are not Fault Active or Test Fail this Key ON: |
| - | DTCs P0815, P0816, or P1876 |
| • | Ignition voltage is 8.6-18.0 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 D6 -- and for 600 seconds in PARK, REVERSE, NEUTRAL, D2, D4, or D6.
P0816
The TCM detects a Stuck ON downshift switch for 3 seconds in PARK, REVERSE, NEUTRAL, or D6 -- and for 600 seconds in PARK, REVERSE, NEUTRAL, D2, D4, or D6.
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 operation. |
Conditions for Clearing the DTC
DTCs P0815, P0816, P0826, and P1876 are Type C DTCs.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics
Connector End View Reference
Component Connector End Views
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
With the engine ON, engage the Tap Up and Tap Down switch positions while observing the Driver Shift Request scan tool parameter. The parameter should change to reflect the selected Up or Downshift switch position and with no Up or Downshift switch position
selected the parameter should display None.
Circuit/System Testing
P0815
- Select the Driver Shift Request parameter.
- Disconnect the automatic transmission (AT) TAP shift switch connector.
| ⇒ | If the parameter status changes from Upshift to Invalid, replace the AT TAP shift switch. |
| ⇒ | If the parameter status does not change, replace the control solenoid (w/body and TCM) valve assembly. |
P0816
- Select the Driver Shift Request parameter.
- Disconnect the automatic transmission (AT) TAP shift switch connector.
| ⇒ | If the parameter status changes from Downshift to Invalid, replace the AT TAP shift switch. |
| ⇒ | If the parameter status does not change, replace the control solenoid (w/body and TCM) valve assembly. |
P0826
- Inspect the fuse in the ignition 1 voltage circuit for an open.
| ⇒ | If the fuse is Open, test the ignition 1 and the tap up and tap down circuit for a short to ground. |
| ⇒ | If the fuse is OK, test the ignition 1 and the tap up and tap down signal circuit for an Open or Short to Voltage. |
- Test the AT TAP shift switch for correct resistance value, 8.11-8.39 ohms.
| ⇒ | If the resistance is not within specifications, replace the switch assembly. |
| ⇒ | If the resistance is within specifications, replace the control solenoid (w/body and TCM) valve assembly. |
P1876
Key On, engine Off, in PARK, disconnect the Tap Up/Tap Down Enable Switch connector from the switch. Using a scan tool, observe the Tap Up/Down Enable parameter in Body and Accessories/Instrument Panel scan tool data list. The parameter should display
Disabled.
| ⇒ | If the parameter does not display Disabled while disconnected, test the Tap Up/Tap Down Enable signal circuit for a short to ground. If no short to ground is found, replace the BCM. |
| ⇒ | If the parameter displays Disabled when disconnected and Enabled when connected, ensure the mechanical enable switch linkage is not bent, binding, or damaged and if no concerns are found, replace the Tap Up/Tap Down Enable switch. |
| ⇒ | If the parameter displays Disabled at all times, test the Tap Up/Tap Down ground circuit for an open or short to voltage. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Replace the control solenoid (w/body and TCM) valve assembly. Refer to
Control Module References for replacement, setup, and programming. |
