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Discussion Starter · #1 · (Edited)
I had the "SERVICE 4WD SYSTEM" fault flash up randomly on my way home from work one day,
It stayed off for some time after that,
The fault kept coming back more frequently, over a three month period.
I went to the dealer on multiple occassions, They pulled codes and could not work anything out, were about to rip the transmission apart to find the problem.
The faults became more frequent also including the Traction Control to start playing up.
Also my computer randomly resetting when turning the car off.

I FIXED THE PROBLEM by tightening 2 NUTS and 1 BOLT...

My battery was sliding 1.5 inches either way, I live in the mountains among rough winding roads. The electronics were loosing earth, causing all my problems, I have not had a fault in over three weeks since tightening the terminals and the battery bracket (Which I must say is pretty piss poor design) for a vehicle that pulls as many G's around a corner.

Found when I lost all power half way through start (Complete black out)... went to jump start the vehicle and when I wiggled the earth on the battery, the stereo come back on.

JUST BEFORE YOU GO BUYING ANY COSTLY PARTS, LABOUR OR CHANGING FLUIDS ETC. ETC. Check your battery teminals and battery mount.
 

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Discussion Starter · #3 · (Edited)
Yes I was scratching my head for sometime, thinking a near new car should not be doing this, did not find any real answers on the other posts, this worked for me, not saying it is the be all and end all fix to the problem.

I was reading about the intermittent "Service 4WD System" faults on this forum, I could nearly guarantee it is an earth fault caused by a sliding battery.

Among the fault codes pulled from the dealer were "Transmission Motor Performance" and "Low Battery"
The Traction Control System did not start playing up till later... Possibly really bad earth problems.

My wallet can now concentrate on buying fuel instead of parts now...

NOTE: The terminals may seem tight enough to conduct electricity, but would pay to give them a tweak. Also the battery may take some effort to move, but tweak that bolt as well. The problem took so long to diagnose because they did seem OK, but not OK enough. You may be suprised at how many turns you get with a spanner.
 

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Great post! I have spent over 300 dollars in fluids for the drivetrain to have the service 4wd come on again. No fault codes our anything. I have the same problems you mentioned. Thank you for this post.
 

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just fixed similar issues... i think (knock on wood) service 4wd came on and off a couple of times over the past few weeks, no codes in the diablosport. then this morning the jeep is completely dead and i'm puzzled because the battery is a couple of months old, tried jumper cables, got a millisecond of life and dead again.

came and searched, saw this, tightened em up and good to go.
 

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Hey guys, here's some more help on this.

Here's the story: I had never had any troubles with my stock TC at all. I got some exhaust work done, where a significant amount of welding was done under the truck. Immediately after coming down from the lift, I got the "Service 4WD System" EVIC message. The message was on permanently, it persisted through loading several tunes and would come up immediately upon starting the truck and stay up. I had no codes (active or pending) visible on my ODB scanner.

I did the parking lot tight turning test (a 360 degree turn as tight as possible), and had no noise or binding with ESP on or off.

I inspected the wiring under the truck, I found no obvious place where it was cut, burned, etc. There is a wire harness that goes very close to the driver's side header (where it connects to midpipe) that showed some burn through on the outer thermal insulation, but there was no insulation damage to any of the wires in that bundle, but that heat damage to the outer bundle was certainly not new from the muffle shop.

I thought it could be coincidence about it happening immediately after the welding, but I was very suspicious. I found this thread and I did check my battery terminals, the pos and neg cables were tightened down very tight on those.

The other thing, I wasn't completely sure that I was 2wd, but I was doing burnouts everywhere. I raced someone from a light and was sideways for 300 feet. Since I'm experimenting with new tunes and some hardware changes, I couldn't figure out if this was new found power or just being 2wd (although I suspected 2wd).

Anyway - I decided to check all the fuses related to TC, FDCM, ABS, etc. I found a blown fuse in the Power Distribution Center (fuse box nearest the brake master cylinder). It was the 30A FDCM/E-Diff fuse (Fuse #33). Replaced it and all is back to normal again.

So this is another thing to check if you get this message and oh by the way, pulling that fuse will give you 2WD in case you want to play! Its probably not good on your TC, but it does work.
 

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I had the same issue with the battery moving side to side until it eventually snapped the ground connector and left me stranded in the Sierra Madre Mountains in Mexico. I had a piece of wood made that fit between the battery and the side of the battery tray and bolted down so it did not move.
 
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