Operation CHARM: Car repair manuals for everyone.
Home >> Cadillac >> 2012 >> CTS Wagon RWD V6-3.6L >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> P Code Charts >> P0815

P0815




DTC P0815, P0816, P0826, or P1876

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 1 Circuit

DTC P0816
- Downshift Switch 1 Circuit

DTC P0826
- Up and Down Shift Switch 1 Circuit

DTC P1876
- Up and Down Shift Enable Switch Circuit Low Voltage

Diagnostic Fault Information






Circuit/System Description

The drivers shift control (DSC) also known as the Tap UP/Down feature allows the driver to shift or change gears similar to a manual transmission. Activating the DSC is accomplished by placing the shift lever in the manual (M) mode position. To place the shift lever in M position, move the shift lever to the right from the drive (D) position gate. When the shift lever is in the M position an upshift is accomplished pushing the shift lever forward. A downshift is accomplished by pulling back or pushing rearward on the shift lever. A redundant set of Tap UP/Down switches are available on the steering wheel horizontal crossbar facing the instrument panel. The plus (+) switch is located on the right side of the steering wheel and the minus (-) switch is located on the left side of the steering wheel. A 12 volt parallel circuit from the body control module (BCM) supplies voltage to the automatic transmission manual shift switch on the shift lever and to the automatic transmission manual shift switches on the steering wheel. A separate signal circuit from each switch to the BCM provides the information on each Tap Up/Down command. The BCM sends the requested command on the serial data line to the transmission control module (TCM) to perform the shift.

Conditions for Running the DTC

P0815, P0816 or P0826
* DTC P0815, P0816, P0826, P182E, P1876, P1877, P1915 or P1761 is not set.
* The ignition voltage is 8.6 volts or greater.
* The engine speed is 400 RPM or greater for 5 seconds.

P1876
* DTC U0100, P0815, P0816, P0826, P1825, P1876 or P1915 is not set.
* The ignition voltage is 8.6 volts or greater.
* The engine speed is 400 RPM or greater for 5 seconds.

Conditions for Setting the DTC

P0815 - Condition 1

The BCM detects a stuck ON Tap Up switch for 1 second in Park or Neutral.

P0815 - Condition 2

The BCM detects a stuck On Tap Up switch for 10 minutes in any forward gear.

P0816 - Condition 1

The BCM detects a stuck ON Tap Down switch for 1 second in Park or Neutral.

P0816 - Condition 2

The BCM detects a stuck ON Tap Down switch for 10 minutes in any forward gear.

P0826

The TCM detects an invalid voltage on the TAP Up/Down Signal Circuit for 1 minute.

P1876

The TCM detects a TAP Enable Switch request 3 times when not in M (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 functions.

Conditions for Clearing the DTC

DTCs P0815, P0816, P0826, and P1876 are Type C DTCs.

Reference Information
Schematic Reference

Automatic Transmission Controls Schematics Electrical Diagrams
Connector End View Reference

* Component Connector End Views Connector Views
* Inline Harness Connector End Views X101

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 Control Module References for scan tool information

Circuit/System Verification

1. Engine running, park brake applied, drive wheels chocked. Shift the transmission into the manual (M) position. Verify with a scan tool the following TCM parameters display the correct values:

* Drivers Shift Control - Inactive
* Drivers Shift Request - None

• If the TCM parameters are incorrect
Refer to Circuit/System Testing below.

• If the TCM parameters are correct

2. Verify with a scan tool the following TCM parameters display the correct values when pushing the shift lever forward or pressing the plus button:

* Drivers Shift Control - Active
* Drivers Shift Request - Upshift

• If the TCM parameters are incorrect
Refer to Circuit/System Testing below.

• If the TCM parameters are correct

3. Verify with a scan tool the following TCM parameters display the correct values when pushing the shift lever rearward or pressing the minus button:

* Drivers Shift Control - Active
* Drivers Shift Request - Downshift

• If the TCM parameters are incorrect
Refer to Circuit/System Testing below.

• If the TCM parameters are correct

4. 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 that you observed 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 automatic transmission manual shift switch harness connector.
2. Ignition ON, test for 11-13 volts on terminal H on the automatic transmission manual shift switch harness connector and ground.

• If not within the specified value
Test the ignition voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

• If within the specified value

3. Ignition OFF, shift the automatic shift lever into the M position.
4. Ignition OFF, test for 6.6-7.0 k ohm between terminal D and terminal H on the automatic transmission manual shift lever harness connector. Also test for 3.7-4.2 k ohm when pushing back on the shift lever and 1.7-2.0 k ohm when pushing forward on the shift lever.

• If not within the specified value
Replace the automatic transmission shift lever assembly.

• If within the specified value

5. Ignition OFF, connect a 3A fused jumper wire between terminal D and terminal H on the automatic transmission manual shift switch harness connector.
6. Ignition ON, test for 11-13 volts on the BCM connector X1 terminal 20 and ground.

• If not within the specified value
Test the signal circuit for a short to ground or an open/high resistance. If the circuit test normal, replace the BCM.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the repair.

* Replace the AT shift program switch. Refer to Transmission Control Replacement Transmission Control Replacement.
* Replace the body control module. Refer to Control Module References Control Module References for replacement, programming, and setup.

pro multis · About Operation CHARM