Bypass Neutral Safety Switch????

I have a 1990 Jeep Cherokee. Can't start the engine. Been told that it is the neutral safety switch. Is there anyway to bypass it? Do I have to replace it?

Here is a good tech site there is a NSS clean procedure on here: http://www.lunghd.com/On_Site_Tech.htm

Assuming you get ignition, but no crank when you turn the key, the NSS is a suspect. Remember, though that the NSS is not involved if it cranks but doesn't start, and also not involved if you get no sign of ignition on. Its function here is only to interrupt the ground path to the starter relay.

Yes, you can bypass it to start, by finding the correct terminal and grounding it, either at the switch or at the starter relay itself.

But if it's just a dirty NSS, usually you can temporarily get going by starting in neutral rather than park. Remember that there's a reason it's called a "safety" switch, so if you bypass, fix it ASAP.

I think there are a number of threads here on which terminals are which. However, if the NSS is really bad, it might also affect transmission behavior and backup lights, because it's more than just a safety switch on this model.

If it really is the NSS, the directions for removing it and cleaning it are worth big money! Be very careful removing it if it's corroded. Take your time and don't pry the aluminum shaft of the switch apart. Check threads here, and you'll find many hints for getting a stubborn one off. This is a very expensive part, and even if you're used to mechanics' wages for your work, it's worth more than a couple of hours of your time to get off whole!

Just clean it, takes like 30 minutes. I had that problem last year when I was heading back from a trip. It sucked but it was an easy fix.

Tenny said:

Just clean it, takes like 30 minutes. I had that problem last year when I was heading back from a trip. It sucked but it was an easy fix.

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It's dead easy to fix, but (Californians may be unaware of this :woohoo: ...) if you live in the rust belt it can be a bear to get off in one piece!

Well, it won't crank in either park or neutral. Still safety switch? I am assuming so after reading numerous threads. Got the wire disconnected, adjusting bolt off, and the shaft bolt along with the washer. Problem here is, HOW DO YOU SIMPLY PULL IT OFF THE SHAFT?? This is where the problem is, now! GRRRR, it's irritating! So, once I get it off, I open it and clean it out? Do I put any kind of rust inhibitor in it? WD40 or something?

socronaut said:

Well, it won't crank in either park or neutral. Still safety switch? I am assuming so after reading numerous threads. Got the wire disconnected, adjusting bolt off, and the shaft bolt along with the washer. Problem here is, HOW DO YOU SIMPLY PULL IT OFF THE SHAFT?? This is where the problem is, now! GRRRR, it's irritating! So, once I get it off, I open it and clean it out? Do I put any kind of rust inhibitor in it? WD40 or something?

Click to expand...

There's the rub. That aluminum outer shaft seizes to the steel shaft from the transmission. Soak it well with penetrant, but whatever you do, do not ever try to pry the aluminum outer shaft apart at the splits, or it will break.

There's usually a very small amount of end play in the steel shaft, so one thing you can try is, very carefully, to use some kind of prying tool to hold the switch body as far out as the play allows, and then use a small soft (brass is good) hammer to tap the end of the steel shaft. If you're lucky, this will break the corrosion bond. Even then, you might have to move it in and out a number of times before it comes all the way off the shaft. The goal here is to get any in-out movement at all. Once you have that, you can add some more oil, and work it gently until it slides off.

I haven't done this job in a while (both mine are stick shifts now), but when I did it last, I used silicone grease inside. There shouldn't be much if any corrosion problem, because the switch is well sealed. It's more a matter of grime and wear. I think the link referenced above will give you more advice.

socronaut said:

I have a 1990 Jeep Cherokee. Can't start the engine. Been told that it is the neutral safety switch. Is there anyway to bypass it? Do I have to replace it?

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cleaning is the best fix for safety's sake, but after you get it done, carry a small alligator clip jumper wire for insurance. If the switch ever acts up again, you can jump from the starter relay to ground and get home without much time lost.

on the relay, you are looking for the black wire with a white tracer and connecting that terminal (diagonally opposite from the big B+ terminal) to the chassis or battery neg (-) post. If done correctly, you should have "start" in ANY gear, so use caution!

--Shorty

Dad just stuck a toggle switch on his '90 and the family is smart enough to know better that to start it in gear.

pull the connector apart where the wire from the NSS connects to the harness (under the hood next to tranny dipstick) and on the harness side stick a flat female wire connector over the two lower center pins. That will make the computer think it is always in park and start....but in any gear so be careful.

Here is what I did.

my link


Verify that the switch is the only thing causing the issue with a jumper between PINS B-C.

Then you can put a temp switch in like I did... However in the 10 months since I put in a bypass switch I have never had to use it.

JAS said:

Here is what I did.

my link


Verify that the switch is the only thing causing the issue with a jumper between PINS B-C.

Then you can put a temp switch in like I did... However in the 10 months since I put in a bypass switch I have never had to use it.

Click to expand...

the diagram of the connector in this write-up does not look like the connector from the 90 model. B and C pins are the two center lower pins. To the best of my knowledge the connector is the same from 87 to at least 95 and probably 96. I haven't yet owned a 97+ so I can't verify on those.

I believe the connector changed in 98, along with the connector for the tranny sensors/solenoids. A few other things with the AW4 changed at the same time.

Thanks a bunch to all of your help. I finally got the switch off took it inside and cleaned it very well as per a previous link that I had seen ealier this week. Cleaned and reinstalled and it still won't crank. What the......? You think the switch is bad? I did order a rebuilt one off Ebay. Should be with me soon. Just bought it for the heck of it and just in case. Any other thoughts if the new switch doesn't work?

OK, question????? Before I remove the switch, should I have it in park or neutral when disconnecting the shift linkage on the left side of the tranny? And when I put the NSS back on, should it be in park or neutral? I'm a bit confused on the instruction in the links. Help please!!

You shouldn't have to disconnect any shift linkages to get the switch off, as I recall, and it's got a flat on the shaft to orient it when you put it back on. You do need to make the fine adjustment by rotating the switch body.

If it still doesn't crank, you should at least temporarily bypass it to see if it cranks then. If it doesn't then your next suspect is the start relay, then work your way down the electrical path to the starter itself.

Just installed the switch as per manual. Still no start. Any other ideas?

socronaut said:

Just installed the switch as per manual. Still no start. Any other ideas?

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Start with a continuity check of wires to NSS. One should go to ground, the other to start relay. If that's ok, check start relay (you can swap with one of its neighbors of same type). If that's not it, then you need to work your way down through the wiring to the starter, and check out the starter itself.

Jess said:

the diagram of the connector in this write-up does not look like the connector from the 90 model. B and C pins are the two center lower pins. To the best of my knowledge the connector is the same from 87 to at least 95 and probably 96. I haven't yet owned a 97+ so I can't verify on those.

Click to expand...

Here's the earlier one (mine's an 88)

Got her runnin'. Now I have a rebuilt NSS that I bought for no reason.
****DOES