Pinpoint Test Z: DTC P185B:00

Electronic Locking Differential (ELD) System

Pinpoint Test Z: DTC P185B:00


Normal Operation

When the MSS (Mode Select Switch) is engaged to lock the rear differential, a PWM (Pulse Width Modulated) signal is sent to the ELD (Electronic Locking Differential) field coil by the TCCM (Transfer Case Control Module) through the differential lock control circuit. This PWM (Pulse Width Modulated) signal is initially 98% duty cycle to lock the differential and decreases to 40% duty cycle once the differential is locked. If the differential does not lock, the TCCM (Transfer Case Control Module) continues to send the signal for a set amount of time. Once the differential is locked, the indicator will illuminate steady.

- DTC P185B:00 (Differential Lock-Up Indicator Circuit Low: No Sub Type Information)- When not in locking mode, the TCCM (Transfer Case Control Module) C2371A-20 senses the indicator circuit is shorted to ground and the indicator is always illuminated. This DTC should not set for an open circuit.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors

- TCCM (Transfer Case Control Module)

PINPOINT TEST Z : DTC P185B:00

NOTE:
Make sure the battery is fully charged before performing this pinpoint test.

Z1 CHECK THE TCCM (Transfer Case Control Module) 4WD (Four-Wheel Drive) SWITCH STATUS (4X4_SW) PID

- Ignition ON.

- Enter the following diagnostic mode on the scan tool: DataLogger- TCCM (Transfer Case Control Module).

- Set the MSS (Mode Select Switch) to 4H and pull the knob to lock the rear differential.

- Monitor the 4X4_SW PID.

Does the 4X4_SW PID indicate 4H mode?

Yes
GO to Z2.
No
INSTALL a new MSS (Mode Select Switch). REFER to Mode Select Switch (MSS) . CLEAR the DTCs. TEST the system for normal operation.

Z2 CHECK THE REAR ELD (Electronic Locking Differential) INDICATOR CIRCUIT FOR A SHORT TO GROUND

- Ignition OFF.

- Disconnect: TCCM (Transfer Case Control Module) C2371A.

- Disconnect: MSS (Mode Select Switch).

- Measure the resistance between TCCM (Transfer Case Control Module) C2371A-20, circuit CCF33 (GY/YE), harness side and ground.






Is the resistance greater than 10,000 ohms?

Yes
GO to Z3.
No
REPAIR circuit CCF33 (GY/YE). CLEAR the DTCs. TEST the system for normal operation.

Z3 CHECK FOR CORRECT TCCM (Transfer Case Control Module) OPERATION

- Ignition OFF.

- Disconnect and inspect all TCCM (Transfer Case Control Module) connectors.

- Repair:
- corrosion (install new connector or terminals - clean module pins)

- damaged or bent pins - install new terminals/pins

- pushed-out pins - install new pins as necessary


- Connect all TCCM (Transfer Case Control Module) connectors. Make sure they are seated correctly.

- Operate the system and verify the concern is still present.

Is the concern still present?

Yes
INSTALL a new TCCM (Transfer Case Control Module). REFER to Transfer Case Control Module (TCCM) . TEST the system for normal operation.
No
The system is operating correctly at this time. Concern may have been caused by a loose or corroded connector. ADDRESS the root cause of the connector or pin issues.