Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Pinpoint Test F : Manual Shift-On-Stop (MSOS) Functional Test: Notes
Refer to Four Wheel Drive Systems for schematic and connector information.
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 low (4L) mode, the transfer case low range gear set provides an additional 2.64:1 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.
Possible Sources
- Transfer case and related components
- Wheel and tire assemblies
- Front axle assembly
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.