Neutral Start Switch

[SimpleXJ]

Hi folks,

My 89 XJ is having some wiring issues, and without making this into a long story I would like to ask you all if anyone knows what all the wires to the NSS do. My problem is that when I try to start the jeep the NSS wiring harness smokes - yeah that's bad. I got this jeep from a squirrel who did a crappy job on replacing the engine so now I'm stuck figuring out his handy work on the wiring. The puzzle is this - when I unhook the NSS harness near the trans dipstick, the jeep STILL STARTS but no smoking wires. I know that it should not start with the NSS unhooked, but just to make sure I;m not insane I tried it on my other 2 XJ's and sure enough - no start.

So I'm thinking the squirrel that I bought the jeep from bypassed the NSS somewhere, and that's why it still starts with it unhooked. I have to try to trace where that bypass is and fix it properly.

If anyone knows the functions of the wires that run to the NSS or even where they go, I would appreciate your help greatly.

Thank you all

SimpleXJ

 

[langer1]

Look see if all the ground wires are hooked up first. The plug your talking about has more than NSS wires in it, it's also transmission control wires.

The NSS is just 1 wire and it is grounded by the shifter and goes to the start solenoid at the front of the relay panel. The other wires are 4WD light, and transmission computer wires.
Other than the burned up wires, it sounds like the grounds are not hooked up.

 

[aduke]

i dont have a nns on my jeep it broke when i was cleaning it. in the mean time i just connected the two black wires. i dont have reverse lights which isnt all that bad. im still looking for a cheap nss.

 

[SimpleXJ]

Ok guys, let me clarify that when I say NSS I mean the trans position switch. The little box on the side of the tranny that is controlled by the shiter shaft. I've been messing with it all morning and after disconneting the TCU (on my 89 its a little yellow box under the dash) the thing still starts. The wires that burned up are the center two on the black connector (black and black/white)

Since the jeep fired up with the yellow box unhooked I'm guessing it's not working at all. I opened it up and the circuit board seems fine - no burned components. I also tried pulling the fuse labeled "trans" and the jeep still starts up. I haven't tested this on my other XJ since the wife took it to work, but I'm pretty sure its not supposed to start with the TCU (yellow box) unhooked, right?

If anyone has a diagram for the TCU or can give me some voltage/resistance readings for the TCU connector, I would be most greatful. Of course any ideas on where the problem is are welcomed.

SimpleXJ

PS
Is the NSS a separate deal on the 89 or is it a part of the trans gear position switch on the side of the tranny?

 

[langer1]

Ok guys, let me clarify that when I say NSS I mean the trans position switch. The little box on the side of the tranny that is controlled by the shiter shaft. I've been messing with it all morning and after disconneting the TCU (on my 89 its a little yellow box under the dash) the thing still starts. The wires that burned up are the center two on the black connector (black and black/white)

Since the jeep fired up with the yellow box unhooked I'm guessing it's not working at all. I opened it up and the circuit board seems fine - no burned components. I also tried pulling the fuse labeled "trans" and the jeep still starts up. I haven't tested this on my other XJ since the wife took it to work, but I'm pretty sure its not supposed to start with the TCU (yellow box) unhooked, right?

If anyone has a diagram for the TCU or can give me some voltage/resistance readings for the TCU connector, I would be most greatful. Of course any ideas on where the problem is are welcomed.

SimpleXJ

PS
Is the NSS a separate deal on the 89 or is it a part of the trans gear position switch on the side of the tranny?

The NSS it not part of and has nothing to do with the TCU.

 

[langer1]

Here's the plug ID, click for larger view.

 

[uvaldetxj]

As for the little yellow box, I asked what it was here on the naxja forums a few months ago. I was told it controlled the cruise control. The TCU should be mounted on the passenger side on the lower dash trim. It should be bolted on.

 

[SimpleXJ]

Ok, thanks guys. So the yellow box is cruise control, that would explain why the cruise hasn't worked. I'm gonna start a new thread since this is not the NSS problem now. Thank you for your help everyone.

Regards,

Simple