P1875 4 Wheel Drive Switch Circuit

DTC P1875 4 Wheel Drive Switch Circuit






Circuit Description

When the transfer case is shifted into the 4L position, the 4L switch closes. When the 4L switch closes, the 4L switch grounds the circuit to the powertrain control module (PCM) connector C3 terminal 3. The PCM uses the above information in order to prevent torque converter clutch (TCC) lock-up and 4th gear engagement.

Conditions for Setting the DTC

The PCM uses the vehicle speed sensor (VSS) in order to trigger DTC P1875. Vehicle speed differences between the above components trigger DTC P1875. If the VSS transmission does not function as designed, the transmission may set DTC P1875. The above action may occur even when the 4L signal circuit is both mechanically and electrically in good condition. DTC P1875 sets if the following condition occurs:

- The VSS senses a vehicle speed of more than 10 km/h (6 mp/h) lower than the output shaft speed.
- Two driving cycle detection logic

Action Taken When the DTC Sets

- DTC P1875 stores.
- The malfunction indicator lamp (MIL) turns ON.

Diagnostic Aids

Inspect for the following conditions:
- A faulty 4L switch
- Faulty electrical circuits between the 4L switch and the PCM
- A faulty PCM

The following conditions may cause an intermittent:
- A reduced connection
- Rubbed through wire insulation
- A broken wire inside the insulation

Inspect the PCM harness connectors for the following conditions:
- Backed out terminals
- Improper mating
- Broken locks
- Improperly formed or damaged terminals
- Reduced terminal-to-wire connections

If DTC P1875 cannot duplicate, the information included in the Freeze Frame data may be useful in determining the vehicle operating conditions when the DTC set.

Refer to Wiring Repairs in Wiring Systems when repairing any wiring, Diagnostic Aids

DTC Confirmation Procedure

1. Turn the ignition switch to the LOCK position.
2. Connect the scan tool to the data link connector (DLC).
3. Turn the ignition switch ON.
4. Use the scan tool in order to clear the following items:
- DTC P1875
- Any pending DTCs
5. Start the engine.
6. Apply the brake pedal firmly
7. Shift the manual selector to DRIVE range.
- Remain in the DRIVE range for 30 seconds.
8. Accelerate the vehicle in DRIVE range.
- Continue driving for 10 seconds at 30 km/h (19 mph).
9. Stop the vehicle.
S10. Shift the manual selector to the PARK range.
11. Shift the transfer case lever to the 4L range.
12. Shift the manual selector to DRIVE range.
13. Accelerate the vehicle in DRIVE range.
- Continue driving for 10 seconds at 30 km/h (19 mph).
14. Stop the vehicle.
15. Use the scan tool in order to test for a pending DTC.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame data on the scan tool if applicable. The scan tool creates an electronic copy of the data taken when the fault occurred. The information then stores in the scan tool for later reference.
4. This step test for a short to ground condition.
5. This step test for an open condition.
6. This step inspects for a faulty PCM.