Test M: 4WD Does Not Engage at Speed Correctly

Pinpoint Test M: 4WD Does Not Engage at Speed Correctly

Refer to Vehicle/Diagrams, Four-Wheel Drive System for schematic and connector information.

Normal Operation

When the operator selects 4H mode, the 4X4 control module (PCM) engages a clutch for approximately 5 seconds to synchronize the front and rear driveshafts allowing a mechanical engagement of the transfer case. The 4X4 control module (PCM) also removes the ground path from the integrated wheel ends (IWEs) solenoid, which removes vacuum from the IWEs, allowing them to engage the front axle shaft. Systematically check the necessary inputs and outputs at the 4X4 control module (PCM), internal components of the transfer case, IWE components and drive axles.






This pinpoint test is intended to diagnose the following:

^ Transfer case clutch coil
^ Transfer case
^ 4X4 control module (PCM)
^ Front axle assembly
^ Wiring, terminals or connectors

M1-M3:

M4-M6:

M7-M8:

M9-M10:

M11-M12:

M13-M14:

M15-M16: