GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2008 🢒 G6 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 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

Driver Shift Request

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Tap Up/Tap Down Switch Signal Circuit

0 V

0 V

5-12 V

--

Typical Scan Tool Data

Upshift Switch and Downshift Switch Parameter Data

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Operating Conditions: Turn ON the ignition, with the engine OFF

Parameter Normal Range: Upshift, Downshift, Invalid, or None

Driver Shift Request Status

Invalid

Invalid

Invalid

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

Connector End View Reference

Component Connector End Views

Description and 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. Ignition ON, transmission shift level in M, 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 OFF, disconnect the harness connector at the transmission shift lever.
  2. Test for 300-500 ohms of resistance between the signal circuit terminal F and ground.
    3. ⇒If not within the specified range, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the TCM.
  3. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal C and ground.
    4. ⇒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.
  4. 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.
    3. ⇒If not within the specified range, replace the transmission shift lever.
  3. Test for 2.75-2.95K ohms of resistance between terminals C and F of the automatic transmission control while pressing the upshift button.
    4. ⇒If not within the specified range, replace the transmission shift lever.
  4. Test for 1.20-1.30K ohms of resistance between terminals C and F of the automatic transmission control while pressing the downshift button.
    5. ⇒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 .
    •  Control Module References for TCM or BCM replacement, setup, and programming.