NSS problems & no backup lights

Have you checked out the wiring diagrams for your year jeep?

At first blush, if it starts in any gear or with the switch unplugged, I'd say that you have a short somewhere else in the wiring. The reverse lights may/should be a different issue altogether.

The NSS/PNP typically works to where it interrupts the starter relay's ground and grounds the relay in park or neutral only. Usually it is one wire coming from the starter relay, and then the switch is case grounded meaning it connects that ground wire terminal straight to the case of the switch which inherently grounds it through the transmission and engine, of course in neutral or park only is how it is supposed to function.

The backup lights wiring is usually an ignition powered/fused wire coming into the switch and then a second wire to go back out to the lights. The trans pushes the button or whatever on the switch which connects the first wire to the second and the backup lamps turn on. Only in reverse should that happen.

if you are still able to start without the switch being plugged in, that is saying to me that your starter relay is somehow getting ground from elsewhere.

If the backup lamps are not working no matter what, probably something up with the way you wired those two wires, or the switch is faulty.

The being able to start without the switch in general is a doozy and I'm not sure what the solution to that is honestly. Somewhere up the line I guess the starter relay is getting ground. Let me dig into the 97 manual and make sure I'm not wrong on how it works. If you can't figure it out I could maybe swing by sometime as a second set of eyes. I'm not that far away from Frisco.

Sorry I never saw this post, I would have commented earlier and not two months down the road.

See this page from the 97 FSM. This is the circuit for a 97 NSS, automatic. I wonder if the PCM is providing ground faultily to the starter relay? The PCM is connected to that ground simply as a way to know if the trans is in park/neutral or not before starting. Don't really know the purpose of that but I know that's how it's wired and the circuit shows that. Unless you have a part of that wire exposed and shorting to the chassis/tub, I don't see any other cause for this besides the PCM. A good way to isolate the PCM from the equation would maybe be to depin that wire from the PCM plug and see if it still starts with/without the NSS plugged in.

The backup lights I'm still not sure what the issue is, could be the wiring, the switch you bought, or maybe the trans is not operating the switch properly if that's possible.

OR, maybe your starter relay is stuck closed and allowing it to start all the time once the key is turned? That could be it. Might try swapping it with a known good other relay that fits. Edit: Actually I don't think this is the issue because I'm pretty certain you would have a continuously running starter if the relay were stuck closed.

You could try a continuity test on the NSS starter relay wire and check it with ground to see if they are connected somewhere upstream. If not, I bet it's a stuck relay.

Pull your starter relay. Figure out which 2 pins are for the coil of the relay. Then, one side should have +12v only in the start (not run) position. The other coil contact should have ground only in neutral or park. Put it in any other gear and see if you still get a ground. Pull the plug off of the PCM, still getting a ground? Pull the plug off of your new NSS, still have a ground?

hear said:

It would be helpful if I knew if this subsystem has ever worked since I've owned it. Lots of variables in play since I aquired it: new NSS, new NSS pigtail.... And also new battery cables-- I left the old ones in there since they were wrapped really well into the harness and I didn't want to tear all that apart at the time. I wonder if I somehow introduced an additional ground path?

The reverse lights were included as a symptom because seems like its all tied into that switch. I wonder if I jump/ground one or more of the pins on the NSS pigtail can I get the reverse lights to come on. I suppose it could be a bulb, I haven't actually checked that. d'oh.

Thanks for your reply, I was starting to wonder if I had got put on global mute or something.

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Yeah knowing whether or not the starting issue has existed since before you changed the switch would have been good. Who knows, maybe it would have started unplugged in the past? You wouldn't know the difference unless you deliberately pulled the plug and tried to start it, or if you were messing around trying to start in D or R one day for no reason and it actually worked.

I would do what dbbd1 suggested by checking ground at the relay and then unplugging the PCM and seeing if you still have ground. You very well may have the PCM providing ground input that it isn't supposed to, allowing the relay to switch over anytime you turn the key to start no matter what. I doubt the new battery cables did anything, although maybe I guess. Those shouldn't change the fundamental operation of the vehicle though so I doubt it.

The reverse lights you can try to jumper at the NSS by bridging the two wires. Per the manual, you are looking for the violet/white and violet/black wires. violet/white is fused ignition power, violet/black goes to the lamps. I would check violet/white for power with the key on, if you have power, great, connect it to violet/black and see if the lamps work. If not, change the bulbs, if still not, break in the violet/black wiring somewhere probably. If you don't have power on violet/white with the key on, check the fuse, otherwise maybe a break in that wire instead. If none of that fixes it, you've got some scary voodoo magic going on somewhere because that's all there is to the circuit.

On the off chance your PCM is grounding the starter relay when it shouldn’t be, you could probably splice in a diode so that the ground sense can always get to the PCM but the PCM ground fault can’t go back to the relay. But I’m getting ahead of myself. No clue what the actual issue is yet.