99 WJ , 4.0

Fuse 20 keeps blowing.

I've searched not found much that's lead to what I need to check.
I've tested my turn switch, and HVAC controls.
Also replaced the flasher relay

Problem still exist

I believe it's a short but I'm not sure where to check at

 

I've copied the page out of the service manual to a Word document and attached it here. If this doesn't work I will add-in a pdf...

It appears you may have any one of a few possibilities, but my first inclination would be to check the park/neutral position switch.

 

Thank You!

This is what I needed.

I've ruled out a short on the flasher and the HVAC controls.
I had them both unplugged and still blew a fuse...

I don't have Heated seats so that should narrow it down to the NSS.

But I can still start and drive the jeep just fine with the fuse blown?

I've read several post about sometimes the NSS wire rubbing a bracket but I've been unable to find a picture of where I needed to be looking for the short at.
Is it on the side of the trans where the NSS switch is?

 

Ok, fuse blows when the shifter passes through reverse.
So there is a short there.

Now how is this wire ran and feed so I can prevent the problem

 

Okay, that means the wire to the reverse lights is shorted. Mine was broken off at the plug.

 

NSS shorted maybe ?

 

No, there are 3 wires on the NSS, one for power, one for starter circuit, and one for reverse lights. My reverse lights quit working and we found one wire on the plug had snapped off inside. My mechanic buddy got a new plug and wired it in for me. The way the harness is run, it constantly flexes as the transmission moves and puts stress on the wires at the plug.

 

This is my thoughts as well.

Trouble is finding where it's shorted at in the line.
I checked the cable down by the NSS and it's all in good shape.
One of the wires is slightly exposed out the back of the plug so I'm ordering a new plug. But I can't see where is been able to come in contact with anything.

Is their anything I can do in the mean time to disable the circuit on the return line? Cut the wire off the back of the plug and heat shrink it? I'll just loose reverse lights right?

 

If it still starts with a blown fuse, yeah, you can drive it. You just won't have whatever else is powered by that fuse. I think turn signals are important though. You can cut that wire off the NSS, but you'd better cut the RIGHT one or you won't start it! It's possible the switch is shorted internally, but I've never heard of one doing that.

 

I ordered a new plug.
Should be here by the end of week.

If that doesn't resolve the issue I'm going to try a new switch.

 

You can locate the position of the short circuit with your ohmmeter, providing you have access to each termination for that conductor. With the short-circuit condition enabled, by measuring resistance to the same ground-point (keep a constant long lead length for this test-point) from each of the terminations for the circuit-under-test, you will find that one termination offers the lowest resistance. That will be the closest physical termination or circuit-branch to the location of the short. You can take it from there...

 

Just for jollies, check to see if one of the bulbs is shorted. It just hit me that it might be simple. OR the sockets.

As my Dad used to say, use the KISS technique; "keep it simple sweety!"

 

Yeah, this is why I was wondering if there was a way to isolate the back half of that circuit.

I haven't ohmed anything out yet because that would require me to unplug it.
Since the plug does not appear to be in good shape I'm waiting till I have the new one before I screw it up unplugging it and can't drive it at all...

 

Okay, inside the cargo area there are 2 side panels, one of them has the plug connections for the tail light harness. On ZJs, it's on the driver's side, but I've been told it's on the passenger's side in the WJ. Unplugging that will remove the entire rear lighting from the system. This is where the tow package lighting module goes. I believe they are right about which side it's on because that's where the rear power outlet and CD disc changer goes.

 

Yes! not sure why I didn't think of that before. It's on the driver side for the WJ as well. I installed a trailer harness when I got it so I can disconnect that and check for shorts from that plug.