P185A
Electronic Locking Differential (ELD) System
Pinpoint Test Y: DTC P185A: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 P185A:00 (Differential Lock-Up Input Switch Circuit High: No Sub Type Information)- When not in locking mode, the TCCM (Transfer Case Control Module) C2371A pin 15 senses whether the ELD (Electronic Locking Differential) mode switch circuit has high voltage and if the differential is always engaged. This DTC will not set unless the MSS (Mode Select Switch) is set to 2H or OFF. If the ELD (Electronic Locking Differential) is functioning normally, the differential will immediately lock when the MSS (Mode Select Switch) is activated and the ELD (Electronic Locking Differential) operating conditions are qualified. This DTC will only display during the self-test function.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- TCCM (Transfer Case Control Module)
PINPOINT TEST Y : DTC P185A:00
NOTE:
Make sure the battery is fully charged before carrying out this pinpoint test.
Y1 CHECK FOR TCCM (Transfer Case Control Module) DTCs
NOTE: Failure to place the MSS (Mode Select Switch) in 2H or OFF prior to carrying out a self-test of the TCCM (Transfer Case Control Module) (to disable the ELD (Electronic Locking Differential) field coil) results in inaccurate self-test.
- Ignition ON.
- Set the MSS (Mode Select Switch) in 2H (ESOF (Electronic Shift-On-The-Fly) or 2 speed-torque-on-demand).
- Set the MSS (Mode Select Switch) in OFF (2WD (2-Wheel Drive) ).
- Enter the following diagnostic mode on the scan tool: Self-Test- TCCM (Transfer Case Control Module).
Are any DTCs present?
Yes
If only DTC P185A:00 is retrieved, GO to Y2.
For any other DTCs, REFER to the TCCM (Transfer Case Control Module) DTC Chart Four Wheel Drive (4WD) Systems - 2-Speed Torque-on-Demand.
No
IDENTIFY the customer concern and GO to Symptom Chart - Electronic Locking Differential (ELD) System. Symptom Chart - Electronic Locking Differential (ELD) System
Y2 CHECK FOR A SHORT TO VOLTAGE ON THE LOCKER MODE SWITCH CIRCUIT
- Ignition OFF.
- Disconnect: TCCM (Transfer Case Control Module) C2371A.
- Ignition ON.
- With the MSS (Mode Select Switch) in 2H or OFF (depending upon vehicle option content), measure the voltage between TCCM (Transfer Case Control Module) C2371A-15, circuit CCF32 (WH/GN), harness side and ground.
Is any voltage present?
Yes
GO to Y3.
No
GO to Y4.
Y3 CHECK FOR A SHORT TO VOLTAGE ON THE LOCKER MODE SWITCH CIRCUIT WITH THE MSS (Mode Select Switch) DISCONNECTED
- Ignition OFF.
- Disconnect: MSS (Mode Select Switch).
- Ignition ON.
- Measure the voltage at TCCM (Transfer Case Control Module) C2371A-15, circuit CCF32 (WH/GN), harness side and ground.
Is any voltage present?
Yes
REPAIR circuit CCF32 (WH/GN). CLEAR the DTCs. TEST the system for normal operation.
No
INSTALL a new MSS (Mode Select Switch). REFER to Mode Select Switch (MSS) . TEST the system for normal operation.
Y4 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.