Pinpoint Test I: ESOF Functional Test

WARNING: When directed to drive the vehicle as part of this test, drive the vehicle on a hard surface in an area without traffic to prevent a crash. Failure to follow these instructions may result in personal injury.

NOTE: 4X4 high/low (4H/4L) is not intended for driving on hard/dry surfaces.

I1 CHECK FOR IPC DTCs
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: Self-Test - IPC .
Are any DTCs present?
- Yes : If DTC U0102:00 is retrieved, REFER to MODULE COMMUNICATIONS NETWORK to diagnose lost communication with TCCM . For all other DTCs, REFER to INSTRUMENTATION, MESSAGE CENTER, AND WARNING CHIMES .
- No : GO to I2 .
I2 CHECK 2H OPERATION
- Switch the MSS to 2H while monitoring the message center.
Does the message center display 4X2 for approximately 4 seconds?
- Yes : GO to I5.
- No : GO to I3 .
I3 CHECK FOR TCCM DTCs
- Enter the following diagnostic mode on the scan tool: Self-Test - TCCM .
Are any DTCs present?
- Yes : REFER to the TCCM DTC CHART .
- No : GO to I4 .
I4 CHECK FOR WIND-UP IN 2H
- Drive the vehicle on a dry, hard surface while executing turns.
Is wind-up present in turns?
- Yes : GO to PINPOINT TEST B .
- No : GO to I5 .
I5 CHECK 4H OPERATION
- Switch the MSS to 4H while monitoring the message center.
Does the message center display 4X4 HIGH?
- Yes : GO to I8.
- No : GO to I6 .
I6 CHECK FOR TCCM DTCs
- Transmission in PARK.
- Enter the following diagnostic mode on the scan tool: Self-Test - TCCM .
Are any DTCs present?
- Yes : REFER to the TCCM DTC CHART .
- No : GO to I7 .
I7 CHECK FOR WIND-UP IN 4H
- Drive the vehicle on a dry, hard surface while executing turns.
Is wind-up present in turns?
- Yes : Go to PINPOINT TEST AB in Electronic Locking Differential (ELD) System, Diagnosis and Testing.
- No : Go to PINPOINT TEST AC in Electronic Locking Differential (ELD) System, Diagnosis and Testing.
I8 CHECK FOR STRAIGHT LINE 4H WIND-UP
- Drive the vehicle on a dry, hard surface.
Is straightline wind-up present?
- Yes : GO to PINPOINT TEST H .
- No : GO to I9 .
I9 CHECK 4H WIND-UP IN TURNS
- Drive the vehicle in 4H while turning.
Is wind-up present in turns?
- Yes : GO to I10 .
- No : GO to PINPOINT TEST B .
I10 CHECK 4L OPERATION
- Bring the vehicle to a stop with the transmission in NEUTRAL and switch the MSS to 4L.
Does the 4X4 LOW indicator illuminate correctly?
- Yes : GO to I13.
- No : GO to I11 .
I11 CHECK FOR TCCM DTCs
- Transmission in PARK.
- Enter the following diagnostic mode on the scan tool: Self-Test - TCCM .
Are any DTCs present?
- Yes : REFER to the TCCM DTC CHART .
- No : GO to I12 .
I12 CHECK FOR WIND-UP IN 4L
- Drive the vehicle on a dry, hard surface while executing turns.
Is wind-up present in turns?
- Yes : GO to PINPOINT TEST A .
- No : GO to PINPOINT TEST C .
I13 CHECK FOR 4L WIND-UP IN TURNS
- Drive the vehicle on a dry, hard surface while executing turns.
Is wind-up present and 4L functioning?
- Yes : GO to I14 .
- No : CHECK for TCCM DTCs. REFER to the TCCM DTC CHART . If no DTCs are present, GO to PINPOINT TEST C .
I14 CHECK 4L TO 2H SHIFT
- With the vehicle at a stop and transmission in NEUTRAL, switch the MSS from 4L to 2H.
Does the message center display 4X2 for approximately 4 seconds?
- Yes : GO to I17.
- No : GO to I15 .
I15 CHECK FOR TCCM DTCs
- Transmission in PARK.
- Enter the following diagnostic mode on the scan tool: Self-Test - TCCM .
Are any DTCs present?
- Yes : REFER to the TCCM DTC CHART .
- No : GO to I16 .
I16 CHECK FOR WIND-UP IN 2H
- Switch the MSS to 2H.
- Drive the vehicle on a dry, hard surface while executing turns.
Is wind-up present in turns?
- Yes : GO to PINPOINT TEST C .
- No : GO to PINPOINT TEST A .
I17 CHECK FOR TRANSFER CASE DISENGAGEMENT
- With the vehicle in NEUTRAL, position it on a hoist. Refer to JACKING & LIFTING .
- Rotate the rear driveshaft while observing the front driveshaft.
Does the front driveshaft rotate?
- Yes : REFER to TRANSFER CASE .
- No : GO to I18 .
I18 CHECK FOR LH AND RH IWE DISENGAGEMENT
NOTE: The engine must be idling during the following steps to supply the vacuum required for the IWEs to engage and disengage.
- Start the engine.
- Rotate the LH front tire one revolution forward and one revolution backward while observing the LH front halfshaft and U-joint.
- Rotate the RH front tire one revolution forward and one revolution backward while observing the RH front halfshaft and U-joint.
Does the LH or RH front halfshaft rotate?
- Yes : GO to PINPOINT TEST D .
- No : GO to I19 .
I19 CHECK FOR IWE VACUUM LEAKS
- Ignition OFF.
- Disconnect both vacuum lines from the IWE solenoid.
- Using a vacuum pump, apply 508 mm (20 in) Hg of vacuum to the IWE apply vacuum circuit.
- Observe the vacuum reading.
Did the vacuum drop more than 25 mm (1 in) Hg per minute?
- Yes : CHECK the IWE and related components for leaks. GO to PINPOINT TEST D .
- No : GO to I20 .
I20 CHECK 2H TO 4H SHIFT AT SPEED ABOVE 32 KM/H (20 MPH)
- Switch the MSS to 2H.
- Drive the vehicle on the road and shift from 2H to 4H while driving above 32 km/h (20 mph).
Does the transfer case shift to 4H satisfactorily?
- Yes : The 4WD system is functioning correctly.
- No : GO to PINPOINT TEST G .