P1876
DTC 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 Descriptor
DTC P1876
-
Up and Down Shift Enable Switch Circuit Low Voltage
Circuit/System Description
When the shift lever is moved left of the D position, the transmission will enter sport mode. With the shift lever in this position, the transmission will enter manual mode if the gear shift lever is pressed forward or rearward. This allows the operator to select an upshift by pressing the gear shift lever forward, and downshift by pressing the gear shift lever rearward. The body control module (BCM) supplies a signal circuit to the shift controller. The shift controller has Hall-effect switches connected to a resistor array. When the lever is left of the D position, a voltage drop occurs across the resistor network. When the gear shift lever is pressed forward or rearward, 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
* Engine speed is greater than 400 RPM for 5 seconds.
* Ignition voltage is 9.0 volts or greater.
* DTC P0815, P0816, P0826, P1761, P1825, P1876, P1877, P1915, or U0100 is not set.
Conditions for Setting the DTC
Transmission control module (TCM) detects a TAP Enable Switch request for 3 seconds when the shift lever is in Park, Reverse, or Neutral, a total of 5 times.
Action Taken When the DTC Sets
* DTC P1876 is a Type C DTC.
* TCM inhibits Tap-Up/Tap-Down functions.
* TCM inhibits manual up, manual down shifts with the shift selector.
Conditions for Clearing the DIC/DTC
DTC P1876 is a Type C DTC.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics 6T30/6T40/6T45/6T50 - Automatic Transmission
Connector End View Reference
Component Connector End Views Connector End Views By Name
Description and Operation
* Transmission General Description Transmission General Description
* Electronic Component Description Electronic Component Description
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 Programming and Relearning for scan tool information
Circuit/System Verification
Warning:
Refer to Parking Brake and Drive Wheels Warning Parking Brake and Drive Wheels Warning.
1. Verify there were no internal mode switch (IMS) DTCs set.
• If IMS DTCs were set
Refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.
• If IMS DTCs are not set
2. Ignition ON.
3. Verify the gear shift lever position matches the scan tool TCM Internal Mode Switch parameter while slowly moving the gear shift lever from Park through all ranges.
• If the specified values are not correct
Refer to Range Selector Lever Cable Adjustment 6T30/6T40/6T45/6T50 - Automatic Transmission.
• If the specified values are correct
4. Verify the scan tool Driver Shift Control Mode parameter displays Inactive in the park, reverse, neutral, and drive gear select lever positions, and Active with the gear shift lever left of the D position and pressing the gear shift lever forward or rearward.
• If the Driver Shift Mode parameter does not display the correct values
Refer to Circuit/System Testing below.
• If the Driver Shift Mode parameter displays the correct values
5. Shift lever left of the D position, verify the scan tool Driver Shift Request parameter changes from None to Upshift when the gear shift lever is pressed forward, and from None to Downshift when the gear shift lever is pressed rearward.
• If the Driver Shift Request parameter does not display the correct values
Refer to Circuit/System Testing below.
• If the Driver Shift Request parameter displays the correct values
6. 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 Testing for Intermittent Conditions and Poor Connections.
Circuit/System Testing
Note:
You must perform Circuit/System Verification first.
1. Ignition OFF, disconnect the S3 transmission shift lever electrical connector.
2. Test for less than 5 ohms between the S3 transmission shift lever harness connector terminal 2 and ground.
• If 5 ohms or greater
Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 5 ohms
3. Ignition ON.
4. Verify the scan tool Driver Shift Control parameter displays inactive.
• If Driver Shift Control Parameter does not display Inactive
Test the signal circuit for a short to voltage or ground.
• If signal circuit has short to voltage or ground, repair the signal circuit wire.
• If signal circuit does not have a short to voltage or ground, replace the K9 body control module.
• If Driver Shift Control Parameter displays Inactive
5. Test for 11 volts or greater at the S3 transmission shift lever harness connector between signal circuit terminal 3 and ground.
• If less than 11 volts
1. Ignition OFF.
2. Test for less than 2 ohms in the signal circuit wire from both ends of the wire.
• If 2 ohms or greater, repair the open/high resistance in the signal circuit wire.
• If less than 2 ohms, replace the K9 body control module.
• If 11 volts or greater
6. Ignition OFF, connect the S3 transmission shift lever harness connector, ignition ON.
7. Test for 11 volts or greater between the S3 transmission shift lever connector terminal 3 and ground in the park, reverse, neutral, and drive gear select lever positions by back probing the connector.
• If less than 11 volts
Replace the S3 transmission shift lever.
• If 11 volts or greater
8. Test for 8.0-10.6 volts between the S3 transmission shift lever connector terminal 3 and ground with the shift lever left of the D position.
• If not between 8.0-10.6 volts
Replace the S3 transmission shift lever.
• If between 8.0-10.6 volts
9. Test for 5.1-7.3 volts between the S3 transmission shift lever connector terminal 3 and ground with the shift lever left of the D position and pressed forward.
• If not between 5.1-7.3 volts
Replace the S3 transmission shift lever.
• If between 5.1-7.3 volts
10. Test for 2.0-4.6 volts between the S3 transmission shift lever connector terminal 3 and ground with the shift lever left of the D position and pressed rearward.
• If not between 2.0-4.6 volts
Replace the S3 transmission shift lever.
• If between 2.0-4.6 volts
11. Replace the K9 body control module.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic repair.
Note:
* Perform the Transmission Adaptive Values Learn Programming and Relearning following all transmission related repairs.
* Before replacing the TCM, perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection Control Solenoid Valve and Transmission Control Module Assembly Inspection.
* Transmission Control Replacement Transmission Control Replacement for AT TAP shift switch replacement.
* Control Module References Programming and Relearning for BCM or control solenoid valve assembly replacement, programming and setup.