Wild Comanche Posted August 22, 2017 Share Posted August 22, 2017 I have a 1989 Jeep Comanche 4x4 with the 4-speed automatic transmission. The back-up lights were not always working when the gear shift lever was put in reverse. I bought a new neutral safety switch and installed it. After installing I checked for the back-up light operation and they were now working in reverse only. Engine started in park and neutral. But the engine starts in reverse and drive also. So I tried adjusting the switch. I tried the switch in three different positions. All the way one way, all the way in the opposite direction and halfway between the two. The problem with the engine starting in reverse and drive didn't change. And the normal operation for starting in park and neutral didn't change. And the back-up lights in reverse only didn't change. It is like the adjustment doesn't affect the operation at all. I though a neutral safety switch prevents a vehicle from being started in gear. Any ideas? Thanks........... Link to comment Share on other sites More sharing options...
Dzimm Posted August 22, 2017 Share Posted August 22, 2017 The aftermarket ones are not the best. If you have a helper handy, put it in reverse with the engine off, adjust it back and forth until you find where the lights turn off in both directions. Set it roughly in the middle of those points and you should be good. If not, it's junk. Your best solution here is if you still have the factory NSS. Take it apart and clean it. The dielectric grease they put in them dries up over time and causes problems with the contacts. Reassemble without dielectric grease anywhere near the contacts and it'll be as good as new. Link to comment Share on other sites More sharing options...
HOrnbrod Posted August 22, 2017 Share Posted August 22, 2017 Which NSS did you buy? Some aftermarket unit? Check the adjustment procedure HERE. It also shows the pinouts on the connector and how to check the switch pins for proper continuity. It sounds like your switch is wired incorrectly. Link to comment Share on other sites More sharing options...
JE39 Posted August 22, 2017 Share Posted August 22, 2017 Another thought; maybe a previous owner has bypassed the NSS, to solve a non-start issue?? Link to comment Share on other sites More sharing options...
Eagle Posted August 22, 2017 Share Posted August 22, 2017 Why is starting in neutral and drive a problem? The whole concept of making it impossible to start in gear was a knee-jerk reaction to stupid people doing stupid things. Personally, I would be very happy to see the starter work when the transmission is in gear. For a variety of reasons. Link to comment Share on other sites More sharing options...
HOrnbrod Posted August 22, 2017 Share Posted August 22, 2017 Why is starting in neutral and drive a problem? The whole concept of making it impossible to start in gear was a knee-jerk reaction to stupid people doing stupid things. Personally, I would be very happy to see the starter work when the transmission is in gear. For a variety of reasons. Unfortunately not everyone is as smart as we are. :rotfl2: I wouldn't want some fool in front of me starting his/her stalled vehicle in reverse when thinking he/she is in neutral. Or behind me starting in drive. That would make me very angry.. Link to comment Share on other sites More sharing options...
Wild Comanche Posted August 22, 2017 Author Share Posted August 22, 2017 Thanks for the replies. The unit I purchased is a "Toledo Driveline" part # D97991A A340. It wasn't the most expensive NSS on the market. You would think I'd learn after buying a wheel barrow full of aftermarket parts made in China that proved to be faulty. I wish I had tried to start the engine in gear before removing the old unit. As I would know if this peculiar situation existed before I switched the NSS. It doesn't really bother me that it starts in gear, as long as it will still start in neutral and that the back-up lights keep working and it lasts w/o going belly up. But then if it is wired wrong inside, it may not last long. Just thought it was a bit strange that it started in gear also. I don't even know why I tried to start the engine in gear. I think I will rebuild the original NSS and reinstall it and see what happens. At least I know I have a decent starter and battery. The engine started in gear almost as easily as in neutral. Hey, thanks for the input guys and have a good one.............................. Link to comment Share on other sites More sharing options...
Minuit Posted August 23, 2017 Share Posted August 23, 2017 The NSS can be easily cleaned. Just make sure not to lose any of the little parts (when I work with things that have tiny parts in them, I do it working inside of a trash bag so any parts that go flying would be caught) Link to comment Share on other sites More sharing options...
Wild Comanche Posted August 24, 2017 Author Share Posted August 24, 2017 After cleaning all the old crusty black grease from the original NSS and re-lubing the unit, I installed it and low and behold it performs exactly like the aftermarket unit. I can start the engine in P,R,N and Drive. The back-up lights work in reverse. Any adjustment of the NSS position makes no difference as to the backup lights operation, they work in any position. And likewise for the ability to start the engine in P,R,N and Drive, they work in any position. All the gear selector positions work as they should. 1-2 position, 3 position, 3 spds. & overdrive, and reverse. The transmission has been rebuilt. I wonder if the linkage from the transmission to the gear shift lever is set up correctly? It is a puzzlement................. Link to comment Share on other sites More sharing options...
Ωhm Posted August 24, 2017 Share Posted August 24, 2017 Disconnect the NSS connector. Does vehicle start when disconnected? Link to comment Share on other sites More sharing options...
Dzimm Posted August 24, 2017 Share Posted August 24, 2017 Do what Ohm says and see what happens. It sounds like an electrical problem somewhere. Just to be sure check your shift linkage adjustment. I had a problem adjusting my NSS once causing weird start conditions and it turned out my linkage was off by a gear. You mention the trans was rebuilt so maybe it was reinstalled with the linkage in the wrong gear? Also return that unit you bought since the original works just the same. Link to comment Share on other sites More sharing options...
Wild Comanche Posted August 25, 2017 Author Share Posted August 25, 2017 I called the guy that rebuilt the transmission and explained the problem with the engine starting in gear and his only suggestion was that someone must have run a wire between the ignition switch and the starter solenoid. I checked that and didn't find any new wiring other than factory. So then after not finding any wiring modifications, I was going to unplug the NSS electrical connector and see if the engine would still start. But got side tracked when I took a look at the starter relay switch. It looked like the original unit. That would make it 29 years old. I bought a new SMP #SR123 and installed it. That was the problem. Now it only starts in park and neutral. Back-up lights work in reverse only. And I didn't have to readjust the NSS position. I didn't take the original relay apart, but something was definitely amiss. Thanks for all the input. Link to comment Share on other sites More sharing options...
HOrnbrod Posted August 25, 2017 Share Posted August 25, 2017 ^^ Nice troubleshooting. Must have been sticking contacts on the original relay. Thanks for posting your results. :cheers: Link to comment Share on other sites More sharing options...
Dzimm Posted August 25, 2017 Share Posted August 25, 2017 Good to hear! Link to comment Share on other sites More sharing options...
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