I had the “Service 4WD System” message appear on my 2005 Jeep Grand Cherokee Limited (5.7L Hemi with Quadra-Drive II). I checked the wiring from the Final Drive Controller (under the rear seat cushion) and verified the front axle actuator wiring and solenoid were OK (14 ohms across the solenoid wiring) but the rear axle actuator solenoid wiring was open circuit. I checked the resistance at the axle connector and it was also open circuit so the rear axle cover would have to come off. Replacing the actuator solenoid and wiring fixed the problem!
Here are the Jeep Part Numbers:
Parts – Front Axle
52114327AC HARNESS, Electronic Front Axle,With [DSG]
52114003AF ACTUATOR, Axle Locker, With [DSG]
Parts – Rear Axle
52114328AC HARNESS, Electronic Rear Axle, [DSF] Only
52114003AF ACTUATOR, Axle Locker, [DSF] Only
These should be available through any Chrysler dealer (my order took about a week to come in in November 2011).
Post time: Jun-04-2017