Vauxhall Workshop Service and Repair Manuals

DTC P1876

Diagnostic Instructions

DTC Descriptor

Circuit/System Description

When the gear 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 pushing the plus (+) button to change up or minus (-) button to change down. The body control module (BCM) supplies battery voltage, ground, and a signal circuit to the shift controller. The shift controller has Hall-effect switches connected to a resistor array. When the lever is in the M position, a voltage drop occurs across the resistor network. When the plus or minus button is pushed, a corresponding voltage drop occurs across the resistor network. This voltage drop is monitored by the BCM. The BCM will send the request to the transmission control module (TCM) to perform the upshift or downshift.

Conditions for Running the DTC

Conditions for Setting the DTC

The transmission control module (TCM) detects a TAP Enable Switch request for 3 seconds when the gear shift lever is in Park, Reverse, or Neutral, a total of 5 times.

Action Taken When the DTC Sets

Conditions for Clearing the DIC/DTC

DTC P1876 is a Type C DTC.

Reference Information

Schematic Reference

Automatic Transmission Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Verify there are no IMS DTCs set.

⇒	If IMS DTCs are set, diagnose them first.

2. Ignition ON, observe the scan tool Driver Shift Control Mode parameter while moving the transmission gear shift lever through all the positions. The parameter should display Inactive in the park, reverse, neutral, and drive positions, and Active in the M position.
3. Gear shift lever in the M position, verify the scan tool Driver Shift Request parameter changes from None to Upshift when the plus button is pressed, and from None to Downshift when the minus button is pressed.
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 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 .

Circuit/System Testing

1. Ignition OFF, disconnect the S3 gear lever assembly electrical connector from the S3 gear lever assembly.
2. Test for less than 10 ohms between the S3 gear lever assembly harness connector terminal 2 and ground.

⇒	If greater than the specified range, repair the ground circuit.

3. Ignition ON, verify the scan tool Driver Shift Control parameter displays inactive.

⇒	If not the expected results, test the signal circuit between S3 gear lever assembly connector terminal 3 and the K9 BCM for a short to voltage or ground. If the circuit tests normal, replace the K9 BCM.

4. Ignition OFF, connect a test lamp between the S3 gear lever assembly harness connector ignition circuit terminal 1 and ground circuit terminal 2.
5. Ignition ON, verify the test lamp is illuminated.

⇒	If the light stays off, test the ignition circuit for an open/high resistance. If the circuit tests normal, replace the K9 BCM.

6. Test for 11-13 volts at the S3 gear lever assembly harness connector between signal circuit terminal 3 and ground.

⇒	If not within the specified range, test the signal circuit for a short-circuit to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.

7. Ignition OFF, connect the S3 gear lever assembly harness connector.
8. Ignition ON, back probe the S3 gear lever assembly connector and test for 11-13 volts between terminal 3 and ground with the gear lever in park, reverse, neutral, and drive.

⇒	If not within the specified range, replace the S3 gear lever assembly.

9. Use a DMM to monitor the voltage between the S3 gear lever assembly connector terminal 3 and ground with the gear lever in the M position, M position with the tap up plus button depressed, and the M position with the tap down minus button depressed. Compare the readings and verify the voltages are correct for each position as follows:

•	Manual: 8.0-10.6 volts

•	Tap down: 5.1-7.3 volts

•	Tap up: 2.0-4.6 volts

⇒	If not within the specified range, test the signal circuit for a short-circuit to ground or open/high resistance. If the circuit tests normal, replace the S3 gear lever assembly.

10. If all circuits test normal, replace the K9 BCM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Note: