Pinpoint Test B: Clutch Field Coil Electrical Faults
- Refer to Wiring Diagrams Two Wheel Drive/Four Wheel Drive Systems
for schematic and connector information.
Normal Operation and Fault Conditions
When 4WD operation is required, the TCCM provides a PWM voltage to the transfer case clutch field coil. The energized field coil moves a ball and ramp cam to engage a clutch as necessary to provide torque to the front axle.
The TCCM4WD clutch field coil driver monitors the circuit for open circuit, short to power, and short to ground. Redundant safety software compares the PWM command to actual measured current flow in the circuit. REFER to: Four-Wheel Drive Systems - System Operation and Component Description .
DTC Fault Trigger Conditions
DTC Description Fault Trigger Condition TCCM P168A:1D Internal Control Module Transfer Case Control Performance: Circuit Current Out Of Range Upon module wake up, TCCM checked the transfer case clutch current flow (C2371B-9). The measure current flow was either more or less than the allowable range. TCCM P1825:00 4-Wheel Drive Clutch Relay Open Circuit: No Sub Type Information The TCCM outputs a 2%-98% duty cycle on the CLUTCH CTRL circuit (C2371B-9). While an output duty cycle was commanded, no current flow was detected on the circuit. TCCM P1826:00 4-Wheel Drive Low Clutch Relay Circuit To Battery: No Sub Type Information The TCCM outputs a 2%-98% duty cycle on the CLUTCH CTRL circuit (C2371B-9). While an output duty cycle was commanded, the TCCM measured battery voltage or 100% duty cycle. Depending on the power source, this fault may also present a parasitic battery drain symptom. TCCM P1827:00 4-Wheel Drive Low Clutch Relay Circuit To Ground: No Sub Type Information The TCCM outputs a 2%-98% duty cycle on the CLUTCH CTRL circuit (C2371B-9). While an output duty cycle was commanded, the TCCM measured zero voltage or 0% duty cycle. Possible Sources
- CLUTCH CTRL open circuit
- CLUTCH CTRL circuit short to ground
- CLUTCH CTRL circuit short to battery
- Clutch field coil
- B1 CHECK THE CLUTCH CTRL CIRCUIT FOR OPEN
- Ignition OFF.
- Disconnect TCCM C2371B.
- Disconnect transfer case C350.
Is the resistance less than 3 ohms?
Yes GO to B2 No REPAIR the open circuit. - B2 CHECK THE CLUTCH CTRL CIRCUIT FOR SHORT TO GROUND
- Ignition OFF.
- Disconnect TCCM C2371B.
- Disconnect transfer case C350.
- Measure:
Positive Lead Measurement / Action Negative Lead C2371B-9 Ground
Is the resistance greater than 10, 000 ohms?
Yes GO to B3 No REPAIR the short to ground. - B3 CHECK THE CLUTCH CTRL CIRCUIT FOR SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect TCCM C2371B.
- Disconnect transfer case C350.
- Ignition ON.
- Measure:
Positive Lead Measurement / Action Negative Lead C2371B-9 Ground
Is any voltage present?
Yes REPAIR the short to voltage. No INSTALL a new clutch field coil. REFER to: Transfer Case - Vehicles With: 2-Speed Torque On Demand Transfer Case .