Pinpoint Test F: Manual Shift-On-Stop (MSOS) Functional Test

Four Wheel Drive (4WD) Systems - Mechanical Shift

Pinpoint Test F: Manual Shift-On-Stop (MSOS) Functional Test

Normal Operation

When operating in Four-Wheel Drive (4WD) high (4H) mode, the transfer case locks the front driveline to the rear. When set to the LOCK position, the manual hublocks connect the front axle shafts to the wheel hubs. When in 4WD (Four-Wheel Drive) low (4L) mode, the transfer case low range gear set provides an additional 2.72:1 gear reduction. When operating in 2-Wheel Drive (2WD) high (2H) mode, the transfer case decouples the front driveline from the rear driveline. For improved fuel economy, both manual hublocks should be set to FREE in 2H mode.

This pinpoint test is intended to diagnose the following:

- Transfer case and related components

- Wheel and tire assemblies

- Front axle assembly

PINPOINT TEST F : MSOS (Manual Shift-On-Stop) 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.

NOTICE: Vehicles equipped with the Manual Shift-On-Stop (MSOS) system and manual hublocks should not be operated in 4H or 4L mode with the hublocks set to the FREE position. Doing so can result in damage to driveline components.

NOTE: 4H (4X4 HIGH) and 4L (4X4 LOW) are not intended for driving on hard/dry surfaces.

F1 CHECK FOR 2H INDICATION

- Ignition ON.

- Shift the transfer case shift lever to 2H.

- Observe the Instrument Panel Cluster (IPC) 4x4 High and 4x4 Low indicators.

Are both indicators off?

Yes
GO to F2.

No
GO to Pinpoint Test A. Pinpoint Test A: The Four-Wheel Drive (4WD) Indicators Do Not Operate Correctly

F2 CHECK THE MANUAL HUBLOCK OPERATION

- Turn the LH and RH hublocks to the LOCK position.

Do the hublocks turn to the LOCK position?

Yes
GO to F3.

No
INSTALL a new manual hublock as necessary. REFER to Hublock . TEST the system for normal operation.

F3 CHECK FOR MECHANICAL ENGAGEMENT IN 2H

- Drive the vehicle in tight turns on a hard surface.

- Check for the presence of driveline wind up and tire scuff.

Is driveline wind up and tire scuff present?

Yes
GO to Pinpoint Test B. Pinpoint Test B: The Vehicle Does Not Shift Between 2H and 4H Modes Correctly
No
GO to F4.

F4 VERIFY THE SHIFT TO 4H

- Shift the transfer case shift lever to 4H.

Did the transfer case shift lever shift to the 4H position?

Yes
GO to F6.

No
GO to F5.

F5 ATTEMPT TO MECHANICALLY ASSIST 4H SHIFT

- While rolling at speed below 5 km/h (3 mph), shift the transmission to NEUTRAL.

- Shift the transfer case shift lever to the 4H position while the vehicle is rolling at a speed below 5 km/h (3 mph).

Did the transfer case shift lever shift to the 4H position?

Yes
GO to F6.

No
GO to Pinpoint Test B. Pinpoint Test B: The Vehicle Does Not Shift Between 2H and 4H Modes Correctly

F6 CHECK MECHANICAL ENGAGEMENT OF 4H

- Drive the vehicle in tight turns on a hard surface.

- Check for the presence of driveline wind up and tire scuff.

Is driveline wind up and tire scuff present?

Yes
GO to F7.

No
GO to Pinpoint Test B. Pinpoint Test B: The Vehicle Does Not Shift Between 2H and 4H Modes Correctly

F7 CHECK THE 4X4 INDICATOR

- With the transfer case in 4H, observe the IPC (Instrument Panel Cluster) 4X4 indicator.

Does the 4X4 HIGH indicator illuminate?

Yes
GO to F8.

No
GO to Pinpoint Test A. Pinpoint Test A: The Four-Wheel Drive (4WD) Indicators Do Not Operate Correctly

F8 VERIFY THE SHIFT TO 4L

- With the vehicle stationary, shift the transmission to NEUTRAL.

- Shift the transfer case shift lever to 4L.

Did the transfer case shift lever shift to 4L?

Yes
GO to F10.

No
GO to F9.

F9 ATTEMPT TO MECHANICALLY ASSIST A SHIFT TO 4L

- While rolling at speed below 5 km/h (3 mph), shift the transmission to NEUTRAL.

- Shift the transfer case shift lever to the 4L position while the vehicle is rolling at a speed below 5 km/h (3 mph).

Did the transfer case shift lever shift to the 4L position?

Yes
GO to F12.

No
GO to Pinpoint Test C. Pinpoint Test C: The Vehicle Does Not Shift Between 4H and 4L Modes Correctly

F10 CHECK FOR MECHANICAL ENGAGEMENT OF 4L

- Execute tight turns on a hard surface.

- Check for the presence of driveline wind up, tire scuff and limited vehicle speed.

Is driveline wind up and tire scuff present?

Yes
GO to F11.

No
GO to Pinpoint Test C. Pinpoint Test C: The Vehicle Does Not Shift Between 4H and 4L Modes Correctly

F11 CHECK THE 4X4 LOW RANGE INDICATOR

- Observe the 4X4 low indicator.

Is the 4X4 low indicator illuminated?

Yes
GO to F12.

No
GO to Pinpoint Test A. Pinpoint Test A: The Four-Wheel Drive (4WD) Indicators Do Not Operate Correctly

F12 CHECK THE SHIFT FROM 4L TO 2H

- With the vehicle stationary, shift the transmission to NEUTRAL.

- Shift the transfer case shift lever to the 2H position.

Did the transfer case shift lever shift to the 2H position?

Yes
GO to F14.

No
GO to F13.

F13 ATTEMPT TO MECHANICALLY ASSIST 4L DISENGAGEMENT

- Allow the vehicle to roll forward to eliminate shift blockage or driveline wind-up.

- While rolling, shift the transmission to NEUTRAL.

- Shift the transfer case shift lever to the 2H position at a vehicle speed below 5 km/h (3 mph).

Did the transfer case shift lever shift to the 2H position?

Yes
GO to F14.

No
GO to Pinpoint Test C. Pinpoint Test C: The Vehicle Does Not Shift Between 4H and 4L Modes Correctly

F14 CHECK THE MANUAL HUBLOCKS RETURN TO FREE

- Turn the LH and RH manual hublocks to FREE.

Will the hublocks turn to the FREE position?

Yes
GO to F15.

No
INSTALL a new manual hublock. REFER to Hublock . TEST the system for normal operation.

F15 VERIFY THAT THE HUBLOCKS DISENGAGE IN THE FREE POSITION

- Lift and support the vehicle so that the front tires are a few inches off the ground.

- Rotate the LH front tire while observing the LH front axle shaft and U-joint.

- Rotate the RH front tire while observing the RH front axle shaft and U-joint.

Does either axle shaft rotate?

Yes
INSTALL a new manual hublock on the axle shaft that rotated. REFER to Hublock . TEST the system for normal operation.

No
GO to F16.

F16 VERIFY THAT THE TRANSFER CASE DISENGAGED MECHANICALLY

- Apply the parking brake.

- Rotate the front driveshaft.

Does the front driveshaft rotate?

Yes
The 4WD (Four-Wheel Drive) system is operating correctly.

No
REPAIR the transfer case as necessary. TEST the system for normal operation.