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Service 4WD System Finally FIXED!

43K views 9 replies 8 participants last post by  joejunk 
#1 · (Edited)
I replaced all 4 of my wheel speed sensor with no luck with the 4WD light. I then read a ton of threads and found it was more then likely the wire harness for the solenoid on the inside of the front or rear diff.

-Hop under your jeep to the rear or front diff.
-At the top there is one wire connection and only one disconnect it.
-Throw some test leads on the sensors 2 male pins and make sure your reading 14 ohms.
-If you read 0 then your wire harness on the inside of the diff to the solenoid actuator is busted.

My front diff solenoid read 0 ohms. Cracked the front diff cover and found the wire harness was completely broke. Replaced the harness $10 part from stealership, replace fluid with mobile1 75-140 with friction modifier from dealership and Service 4WD light went off instantly :thumbsup: . Hope this helps The pic is the harness that sticks out the top of the diff. You can see the two wires that go into the inside of the diff an connect to the solenoid are completely cut off.
 

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#4 ·
I will have to try that, as my service 4wd systems has been on since i bought it in may, had mot and rear diff fluid leaking into rear brakes, so £500 later got through the mot, low 4wd still works but service 4wd system still on, uk jeep said £120 to change diff oil and new sensor(£26) to sort out = £146.00.
 
#7 ·
I got the 'Service 4WD System' message. I have QDII system. Turns out the front diff solenoid actuator went bad at 125K miles. It measured 0 ohms. The mini harness inside the diff was OK. Bought a kit that includes actuator and front (short) and rear (long) harness. Went through the hassle of draining, opening, R&R actuator in the front diff only to have the replacement actuator be faulty. It would actuate and stick in position locking the front diff and causing binding while turning. Had to do the whole repair all over, but second actuator fixed it! What a PIA to do it twice.
 
#10 ·
what an old thread but my Jeep is still going strong even though it is a POS. My Service 4x4 System light came on back in September along with the Service Elec brake system. I recently replaced both front ABS sensors again. I thought the issue was resolved since I was able to drive 80 miles before the lights came back on. Well I decided to take it to my local dealer and their diags came up with "tech found internal failure on right rear wheel speed sensor. replaced and cleared code". $481 later I have the Jeep back as of yesterday. Fingers crossed that this resolves the issue.
 
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