6L80-E Automatic Transmission
DTC P0815, P0816, P0826, or P1876
DTC Descriptor
This diagnostic procedure supports the following DTCs:
^ DTC P0815 Upshift Switch Circuit
^ DTC P0816 Downshift Switch Circuit
^ DTC P0826 Up and Down Shift Switch Circuit
^ DTC P1876 Up and Down Shift Switch Performance - Range Switch Not in D3
Diagnostic Fault Information
Important: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
Circuit/System Description
The TAP Shift system allows the driver to manually shift gears by using the TAP Shift switches located on the automatic transmission shifter. Pushing the Up switch will command an upshift and pushing the Down switch will command a downshift. Ignition voltage flows from the Ignition 1 fuse through the Tap Switch resistor array to the TCM. The TAP Shift system is activated when the gear selector is in the manual (M) position. In the M range position, the TAP 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
The engine speed is between 500-6,500 RPM for at least 5 seconds.
DTCs P0815 or P0816
^ No DTC P0826.
^ No DTCs P1815 or P1826.
^ The time since the last gear selector range change is greater than 6 seconds.
DTC P1876
^ No DTC U0100.
^ No DTCs P0815, P0816, or P0826.
^ No DTCs P1825 or P1915.
Conditions for Setting the DTC
DTC P0815
The TCM detects an upshift request for 3 seconds in PARK, REVERSE, NEUTRAL, or D6- and for 600 seconds in PARK, REVERSE, NEUTRAL, D2, D4, OR D6.
DTC P0816
The TCM detects a downshift request for 3 seconds in PARK, REVERSE, NEUTRAL, or D6- and for 600 seconds in PARK, REVERSE, NEUTRAL, D2, D4, or D6.
DTC P0826
The TCM detects an invalid voltage on the TAP Up/Down Signal Circuit for 5 seconds.
DTC P1876
The TCM detects for 6 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
Connector End View Reference
^ Automatic Transmission Inline 16-Way Connector End View
^ Automatic Transmission Internal Connector End Views
DTC Type Reference
^ Diagnostic Trouble Code (DTC) Type Definitions
^ Diagnostic Trouble Code (DTC) List/Type
Electrical Information Reference
^ Circuit Testing
^ Connector Repairs
^ Testing for Intermittent Conditions and Poor Connections
^ Wiring Repairs
Circuit/System Verification
DTCs P0815, P0816, or P0826
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.
DTC P1876
With the engine ON, move the transmission range selector from the Park (P) range to the Manual (M) range while observing the Driver Shift Control parameter on the scan tool. It should change from Inactive in Park to Active when in the Manual range.
Circuit/System Testing
DTC P0815
1. Select the Driver Shift Request parameter.
2. Disconnect the Automatic Transmission (AT) shift program switch connector.
3. If the parameter status changes from Upshift to Invalid, replace the AT shift program switch.
4. If the parameter status does not change, replace the control solenoid (w/body and TCM) valve assembly.
DTC P0816
1. Select the Driver Shift Request parameter.
2. Disconnect the Automatic Transmission (AT) shift program switch connector.
3. If the parameter status changes from Downshift to Invalid, replace the AT shift program switch.
4. If the parameter status does not change, replace the control solenoid (w/body and TCM) valve assembly.
DTC P0826
1. Inspect the fuse in the ignition 1 voltage circuit for an open.
2. If the fuse is Open, test the ignition 1 and the Tap/Up and Tap/down circuit for a short to ground.
3. 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.
4. Test the AT shift program switch for correct resistance value, 8.11-8.39 ohm.
5. If the resistance is not within specifications, replace the switch assembly.
6. If the resistance is within specifications, replace the control solenoid (w/body and TCM) valve assembly.
DTC P1876
^ Key On, engine Off, in PARK, disconnect the Tap Up/Tap Down Enable Switch connector from the switch. Observe the Driver Shift Control parameter on the scan tool. The parameter should display Inactive.
^ If the parameter does not display Inactive 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 Inactive while disconnected and Active 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 Inactive at all times, test the Tap Up/Tap Down ground circuit for an open or short to voltage.
Repair Instructions
Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests
^ Replace the AT shift program switch.
^ Replace the control solenoid (w/body and TCM) valve assembly. Refer to Control Module References for replacement, setup, and programming. Programming and Relearning