P0815
DTC P0815, P0816, or P0826
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
Typical Scan Tool Data
Circuit/System Description
When the shift lever is placed in manual mode (M), the driver shift request (DSR), also known as the tap shift function, is activated. The DSR allows the vehicle operator to shift gears by pressing the plus (+) button for an upshift or the minus (-) button for a downshift. The body control module (BCM) provides ignition voltage to the resistor array in the switch. When a plus or minus button is pressed, there is a corresponding change in the resistance, resulting in change to the voltage drop. The change in voltage on the signal circuit is monitored by the transmission control module (TCM). The TCM commands the upshift or downshift, providing the operating conditions are correct for the shift.
Conditions for Running the DTC
P0815 or P0816
* Engine speed is 400 RPM or greater for 5 seconds.
* Ignition voltage is 9.0 volts or greater.
* DTC P0815, P0816, P0826, P1761, P182E, P01876, P1877, or P1915 is not set.
* Time since last range change is 1 second or greater.
P0826
* Engine speed is 400 RPM or greater for 5 seconds.
* Ignition voltage is 9.0 volts or greater.
* DTC P0826 or P1761 is not set.
Conditions for Setting the DTC
P0815 - Condition 1
TCM detects an upshift request for 1 second in PARK or NEUTRAL.
Condition 2
TCM detects an upshift request for 10 minutes with the transmission in a forward range.
P0816 - Condition 1
TCM detects a downshift request for 1 second in PARK or NEUTRAL.
Condition 2
TCM detects a downshift request for 10 minutes with the transmission in a forward range.
P0826
TCM detects an invalid voltage on the TAP up/down signal circuit for 1 minute.
Action Taken When the DTC Sets
* DTCs P0815, P0816, and P0826 are Type C DTCs.
* TCM disables TAP shift operation.
Conditions for Clearing the DTC
DTCs P0815, P0816, and P0826 are Type C DTCs.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics Electrical Diagrams
Connector End View Reference
Component Connector End Views 1-2 Shift Solenoid (SS) Valve (MN5)
Description and Operation
* Transmission General Description Transmission General Description
* Transmission Component and System Description Transmission Component and System Description
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. Ignition ON.
2. Verify with a scan tool no internal mode switch (IMS) DTCs were set.
• If IMS DTCs were set
Refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.
• If IMS DTCs were not set
3. Verify the gear shift lever position matches the scan tool IMS parameter while slowly moving the gear shift lever from Park through all ranges.
• If parameter is not correct for each lever position
Refer to Range Selector Lever Cable Adjustment Adjustments.
• If parameter is correct for each lever position
4. Gear select lever in manual mode (M) position.
5. Verify the scan tool Driver Shift Control parameter displays Active.
• If parameter does not display Active
Refer to Circuit/System Testing below.
• If parameter displays Active
6. Verify the scan tool Driver Shift Request displays None.
• If parameter does not display None
Refer to Circuit/System Testing below.
• If parameter displays None
7. Observe the scan tool Driver Shift Request parameter while pressing and releasing the Tap Up (+) button and Tap Down (-) button. The parameter should change from None to Upshift when the + button is pressed and from None to Downshift when the - button is pressed.
• If parameter does not display correct values
Refer to Circuit/System Testing below.
• If Parameter displays correct values
8. After performing the above steps, verify that the DTC does not reset by operating the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions you observe from the Freeze Frame/Failure Records data. If the vehicle passes the Circuit/System Verification procedure, then STOP. Do not perform the Circuit/System Testing or Component Testing as this may result in an unnecessary part replacement. Refer to Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections.
Circuit/System Testing
1. Ignition OFF, disconnect the vehicle harness at the 2-way connector at the transmission shift lever assembly, Ignition ON.
2. Verify a test lamp illuminates between the vehicle harness connector ignition circuit terminal 1 and ground.
• If test lamp does not illuminate
1. Ignition OFF, remove the harness connector at the K9 body control module.
2. Test for infinite resistance between the vehicle harness transmission shift lever assembly connector ignition circuit terminal 1 and ground.
• If less than infinite resistance, repair the short to ground in the circuit.
• If infinite resistance.
3. Test for less than 2 ohms in the ignition circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K9 body control module.
• If test lamp illuminates
3. Ignition OFF, remove the vehicle harness at the transmission.
4. Test for infinite resistance between the shift lever harness connector signal circuit terminal 2 and ground.
• If less than infinite resistance
Repair the short to ground in the circuit.
• If infinite resistance
5. Test for less than 10 ohms in the signal circuit end to end
• If 10 ohms or greater
Repair the open/high resistance in the circuit.
• If less than 10 ohms
6. Test for 8.0-8.5 k ohms between the shift lever assembly connector terminals 1 and 2.
• If not between 8.0-8.5 k ohms
Replace the shift lever knob.
• If between 8.0-8.5 k ohms
7. Test for 2.7-3.1 k ohms between the shift lever assembly connector terminals 1 and 2 with the Tap Up switch (+) button pressed.
• If not between 2.7-3.1 k ohms
Replace the shift lever knob.
• If between 2.7-3.1 k ohms
8. Test for 1.1-1.5 k ohms between the shift lever assembly connector terminals 1 and 2 with the Tap Down switch (-) button pressed.
• If not between 1.1-1.5 k ohms
Replace the shift lever knob.
• If between 1.1-1.5 k ohms
9. Replace the Q8 Control Solenoid Valve Assembly.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Refer to Control Module References Programming and Relearning for BCM replacement, programming and setup.
* Refer to Transmission Control Replacement Transmission Control Replacement for AT TAP shift switch replacement.