Pinpoint Test K: Four-Wheel Drive (4WD) System Functional Test
- Normal Operation and Fault Conditions
The four wheel drive system functional test will isolate and test each sub-system to determine if the subsystem is functioning properly. If a fault is found, additional testing of the suspect subsystem will be required.
When operating in 2H mode, the transfer case clutch is de-energized. In 4A, the TCCM will apply the clutch when needed to control wheel slip. When operating in 4H and 4L modes the transfer case clutch is fully applied. The vehicle will bind in turns in 4H and 4L modes
Possible Causes
- 4WD system or related components
NOTE: 4X4 High and 4X4 Low are not intended for driving on hard/dry surfaces. Using these modes while driving on these surfaces may produce noises like intermittent clunking but does not damage driveline components. - K1 CHECK THE MODULES FOR ON DEMAND DTC (DIAGNOSTIC TROUBLE CODE)
- Ignition ON.
- Gear Selector in Park.
- Enter the following diagnostic mode:
- TCCM On Demand Self-test
- ATCM On Demand Self-test
Is any DTC retrieved?
Yes REFER to the DTC Chart above. No GO to K2 - K2 CHECK ATCM INPUT TO THE TCCM (TRANSFER CASE CONTROL MODULE) IN 2H
- NORMAL drive mode.
- Gear selector in P
- Engine running.
Access the TCCM and monitor the 4X4_SWPID
- Enter the Diagnostic Mode: Datalogger >> TCCM.
Does the 4x4_SW display Two Wheel Drive?
Yes The TCCM recognizes a valid input from the ATCM. GO to K3 No INSTALL a new ATCM. REFER to: Fuel System - Overview . - K3 CHECK TORQUE ON DEMAND CLUTCH OPERATION IN 2H
- NORMAL drive mode.
- Drive the vehicle on a dry, hard surface while full lock turns.
Is wind-up / vehicle bind present?
Yes The transfer case is unable to disengage 4x4. CHECK the transfer case. REFER to: Transfer Case - Vehicles With: 2-Speed Torque On Demand Transfer Case . No GO to K4 - K4 CHECK TORQUE ON DEMAND CLUTCH OPERATION
- SAND drive mode.
- Enter the following diagnostic mode: Datalogger >> TCCM.
- Command 4WD_CLTCH_OUT # to 70-80%.
Access the TCCM and control the 4WD_CLUTCH_OUTPUT (% Duty Cycle) PID
Is wind-up / vehicle bind present?
Yes GO to K5 No The TOD clutch is slipping / not transferring torque. CHECK the transfer case. REFER to: Transfer Case - Vehicles With: 2-Speed Torque On Demand Transfer Case . - K5 CHECK RANGE FORK OPERATION
- Engine running.
- Gear selector in NEUTRAL, vehicle stopped.
- Select 4L on the ATCM (Ford) or SLOW CLIMB drive mode (Lincoln).
Does 4L indicator illuminate on the IPC '
Yes The shift motor moved to engage 4L. GO to K6 No GO to Pinpoint Test C - K6 CHECK 4L OPERATION
- Select 4L on the ATCM (Ford) or SLOW CLIMB drive mode (Lincoln).
- Drive the vehicle up to 10 mph.
Did the transfer case engage LOW range?
Yes The four wheel drive system is operating currently at this time. No The shift motor moved to engage 4L, but the transfer case did not provide a reduced gear ratio. CHECK the transfer case. REFER to: Transfer Case - Vehicles With: 2-Speed Torque On Demand Transfer Case .