Service 4WD + Parksense Error - 4Low Only

[drewkillsit]

There are a handful of threads on here regarding the "SERV 4WD" dash error, but mine doesn't seem to align to those. Here's what happens:

• Shift TC into 4-High - truck drives just fine
• Shift to Neutral, shift TC to 4-Low, return to Drive - shortly after forward movement, 3 on-screen messages begin (see below)
• Continuing to drive with these errors, it drives "jumpy" - with no accelerator input, RPMs jump up and down ~500rpms at a time until it slows to a stop
• Impossible to shift out of 4-Low without first shutting off the truck, turning back on

Errors:

• SERV 4WD
• Traction Control On
• Parksense unavailable
• After shifting back to 4-High or 2-High, errors gone

Others on the forum have had similar issues, and it's quite often been a wheel speed sensor or FAD issue. In some cases, a transfer case actuator or related part. Most often, the error persists or it even begins in 4-High. I tend to think it's a TC issue, because it only occurs after shifting in 4-Low.

In any case, after 2 months of waiting for a Jeep appointment, I left it with them this morning and am bracing for the "sorry, you did too much cool stuff to your Jeep, and now this isn't covered under warranty" call. Wanted to drop a line here and see what people though on whether it's a TC issue and be prepared to ask for an explanation of how my aftermarket parts caused the problem.

For reference, it has 5.13s, RCV axles with FAD maintained and properly installed (yeah, yeah, I know, get the one piece), Tazer recalibrated to gears and tire size.

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[F1REICE]

So....... I have had similar issues. In 4 low if I hit a bump everything flashes lockers turn off and wants to act like in 2wd. Started with transfer case selector switch, no luck. Waiting on a harness repair kit for the plug the transfer case selector switch plugs into. One of the wires was not showing correctly voltage. I will keep you updated on the outcome.

On a side note i was wondering if a tazer would eliminate the problem but not sure.

 

[drewkillsit]

Interesting. Definitely let me know. I just can't really envision how this isn't the TC. Sounds like your repairs have been covered under warranty (?).

 

[homebrewer]

What was the outcome @drewkillsit @F1REICE ?

I've got a similar issue.

 

[drewkillsit]

What was the outcome @drewkillsit @F1REICE ?

I've got a similar issue.

Root cause: my stupidity. Really basic issue. With my Tazer I had recently reset, I set my high ratio to 5.13 and left the low ratio at 4.10 stock. So, when I shifted to low, it would flip out.

 

[homebrewer]

Ah so if I regear to 4.88s on 37s that might be the cause?? Because that's what I did lol.

edit: oh nvm I see what you're saying. I don't have a tazer so I haven't messed with any settings at all.

 

[F1REICE]

Mine was a rubbing wire that was shorting out the 4 x 4 shifter sensor. Dealership fixed it under warranty no issues since.

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