Pinpoint Test D : DTC P185D:00
- Refer to Four Wheel Drive Systems
for schematic and connector information.
Normal Operation and Fault Conditions
When the ELD is fully locked, the indicator illuminates steadily. When the ELDMSS is engaged to lock the rear differential, a PWM signal is sent to the ELD field coil by the TCCM through the differential lock control circuit. This PWM signal is initially 98% duty cycle to lock the differential and then tapers off to a lower duty cycle once the differential is locked. If the differential does not lock, the TCCM module continues to send the signal for a set amount of time. Once the ELD is locked, the indicator illuminates steadily.
DTC Fault Trigger Conditions
DTC Description Fault Trigger Condition TCCM P185D:00 Differential Lock-Up Control Circuit Performance: No Sub Type Information This DTC sets if the locker is not able to engage after a calibratable number of retries or a delta rear wheel condition persists while commanding the ELD ON. Fault clear if locker successfully engages. CLEAR the DTCs if the locker engages successfully Possible Sources
- Wiring, terminals or connectors
- ELD field coil
- NOTE: Make sure the battery is fully charged before carrying out this pinpoint test.
- NOTE: Clean and inspect the internal connector from coil to external ELD connector for damage.
- D1 CHECK THE ABS MODULE WHEEL SPEED SENSOR PIDS
- Enter the following diagnostic mode: ABS Module Datalogger.
- While driving the vehicle at 30 km/h (18 mph), monitor the following wheel speed sensor PIDs:
- Left Front Wheel Speed Sensor (LF_WSPD)
- Left Rear Wheel Speed Sensor (LR_WSPD)
- Right Front Wheel Speed Sensor (RF_WSPD)
- Right Rear Wheel Speed Sensor (RR_WSPD)
- Compare the speedometer reading to the wheel speed sensor PIDs.
Do the wheel speed sensor PIDs and speedometer speeds match within 1.5 km/h (1 mph)?
Yes GO to D2 No VERIFY that the 4 road wheels are the same size and have similar tread depth. CHECK the ABS for faults. - D2 CHECK RESISTANCE OF THE ELD FIELD COIL
- Ignition OFF.
- Disconnect ELD field coil.
- Measure:
Positive Lead Measurement / Action Negative Lead ELD field coil pin 1 component side ELD field coil pin 2 component side
Is the resistance between 2-4 ohms?
Yes GO to D3 No INSTALL a new ELD field coil. REFER to: Differential Carrier - Vehicles With: Electronic Locking Differential (ELD) . REFER to: Differential Carrier - Vehicles With: Electronic Locking Differential (ELD) . - D3 CHECK THE ELD FIELD COIL GROUND
- Measure:
Positive Lead Measurement / Action Negative Lead ELD field coil pin 2 component side Ground
Is the resistance less than 3 ohms?
Yes To repair the rear differential REFER to: Differential Carrier - Vehicles With: Electronic Locking Differential (ELD) . REFER to: Differential Carrier - Vehicles With: Electronic Locking Differential (ELD) . . CLEAR the DTCs. No REPAIR the circuit. - Measure: