4T45-E - Automatic Transaxle
DTC P0815, P0816, or P0826
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* 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
Diagnostic Fault Information
Typical Scan Tool Data
Circuit/System Description
The transmission adaptive pressure (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. The TAP shift system is activated when the gear selector is in the D3 position an is deactivated in all other positions. TAP system is deactivated in all other range positions.
Conditions for Running the DTC
P0815 or P0816
* No TAP system DTC P0826.
* No TFP DTCs P1810, P1816, or P1818.
* The time since the last gear selector range change is greater than 6 seconds.
* The engine speed is greater than 500 RPM for at least 5 seconds.
* The ignition voltage is between 8.6 volts and 18.0 volts.
P0826
* The engine speed is greater than 500 RPM for at least 5 seconds.
* The ignition voltage is between 8.6 volts and 18.0 volts.
Conditions for Setting the DTC
P0815 and P0816
The TCM detects an upshift request for 1 second or greater in PARK/NEUTRAL range, or D4 range for 600 seconds.
P0826
The TCM detects an invalid voltage on the TAP up/down signal circuit for 5 seconds or greater.
Action Taken When the DTC Sets
* DTCs P0815, P0816, and P0826 are Type C DTCs.
* The TCM disables TAP shift operation.
* The TCM commands an alternate coast shift pattern where downshifts occur at higher vehicle speeds while coasting.
Conditions for Clearing the DTC
DTCs P0815, P0816, and P0826 are Type C DTCs.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics (LE5) (Electrical Diagrams)Automatic Transmission Controls Schematics (LZ4) (Electrical Diagrams)
Connector End View Reference
Component Connector End Views
Description and Operation
TAP Shift Operation (TAP Shift Operation)
Electrical Information Reference
* Circuit Testing
* Connector Repairs
* Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
1. Engine Idling, observe the scan tool Driver Shift Request parameter. The reading should display None.
2. Observe the scan tool Driver Shift Request parameter while pressing the tap-up and tap-down switch. The reading should change between Upshift and Downshift.
3. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
1. Ignition ON, observe the scan tool Driver Shift Request parameter. The reading should display None or invalid.
• If not the specified value, replace the transmission shift lever.
2. Ignition OFF, disconnect the harness connector at the transmission shift lever.
3. Ignition OFF, test for less than 10 ohms of resistance between the signal circuit terminal F and ground.
• If greater than the specified range, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the TCM.
4. Ignition ON, test for 8.11-8.39 ohms of resistance between the signal circuit terminal F and ground.
• If not within the specified range, test the signal circuit for a short to voltage or a short to ground. If the circuit tests normal, replace the TCM.
5. Verify that a test lamp illuminates between the ignition circuit terminal C and ground.
• If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
6. If all circuits test normal, test or replace the transmission shift lever.
Component Testing
1. Ignition OFF, disconnect the harness connector at the transmission shift lever.
2. Test for 8.2-8.3K ohms of resistance between terminals C and F of the automatic transmission control.
• If not within the specified range, replace the transmission shift lever.
3. Test for 4.37-4.47K ohms of resistance between terminals C and F of the automatic transmission control while pressing the upshift button.
• If not within the specified range, replace the transmission shift lever.
4. Test for 1.45-1.55K ohms of resistance between terminals C and F of the automatic transmission control while pressing the downshift button.
• If not within the specified range, replace the transmission shift lever.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
* Transmission Control Replacement (Transmission Control Replacement) .
* Control Module References for TCM or BCM replacement, setup, and programming.