Diagnostic Instructions
DTC Descriptor
DTC P1876: Up and Down Shift Enable Switch Circuit Low Voltage
Circuit/System Description
The 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 L (M) position and is deactivated in all other positions.
If the transmission control module (TCM) detects TAP enable switch Active and the IMS switch does not indicate L (M), DTC P1876 sets.
Conditions for Running the DTC
| • | The engine speed is greater than 500 RPM for 5 seconds. |
| • | The ignition voltage is between 9.0 volts and 19.0 volts. |
| • | No TAP system DTCs P0815, P0816, or P0826. |
| • | No IMS DTCs P1825 or P1915. |
Conditions for Setting the DTC
The TCM detects a TAP Enable Switch request for 2 seconds when not in D6 range for 3 times.
Action Taken When the DTC Sets
| • | DTC P1876 is a Type C DTC. |
| • | The TCM disables Tap shift functions. |
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
- Verify there are no IMS DTCs set.
| ⇒ | If IMS DTCs are set, diagnose them first. |
- Ignition ON, transmission in Park, observe the scan tool Driver Shift Control parameter. The reading should display Inactive.
- Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the transmission shift lever.
- Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal A and ground.
| ⇒ | If the test lamp does not illuminate, test the IGN circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM. |
- Verify the scan tool Driver Shift Request parameter indicates Invalid.
| ⇒ | If not the specified value, replace the BCM. |
- Ignition OFF, test for 300-600 ohms between the signal circuit terminal B and ground.
| ⇒ | If less than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the BCM. |
| ⇒ | If greater than the specified range, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the BCM. |
- If all circuits test normal, test or replace the transmission shift lever.
Component Testing
- Ignition OFF, disconnect the harness connector at the transmission control.
- Test for 6.74-6.94 k ohms between terminals A and B.
| ⇒ | If not within the specified range, replace the transmission control. |
- Test for 1.77-1.97 k ohms between terminals A and B while pressing the upshift button.
| ⇒ | If not within the specified range, replace the transmission control. |
- Test for 3.87-4.07 k ohms between terminals A and B while pressing the downshift button.
| ⇒ | If not within the specified range, replace the transmission control. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
Note:
| • |
Control Module References for body control module (BCM) or control solenoid (w/body and TCM) valve assembly replacement, setup, and programming |
