Neutral safety switch

[2w091]

With all the snow, our HMMWV has been getting a workout, it sat outside overnight in -9 temps inbetween snowstorms. When we went out to start it there was a sizzle, then smoke came out from the under the trans shifter. We turned it off, after several attempts at starting there was nothing after the glow plugs turned off. After checking the -20 we think it was isloated to the neutral safety switch, the voltage was low after being in sub-zero cold for two days. I charged the batteries with a pulse charger and she fired right up, we used it the last two days with no problem.

I guess my question is if the switch shorted out, but the vehicle is running fine, is there a concern as to damage to the electrical system.

 

[Retiredwarhorses]

You can bypass the NSS, just plug the harness into it self...if it fried, it might be closed...I would check it with a meter.
or can you start the truck in drive is another test.

 

[2w091]

Not sure which connections to plug into themselves, there are two connections marked 14 A and B and a third connection. If I plug one of the 14's into the third and leave a connection hanging, is that cool?

Thanks in advance for any assitance you can provide!

 

[gimpyrobb]

I think Ziggy might have some of those switches.

The NSN is 5930-00-207-9422

 

[Retiredwarhorses]

Can you start the truck in gear? If no, NSS is working...if it starts is gear, NSS is bad.

 

[Retiredwarhorses]

There are 3 wires...1 is for the 24v lamp that lights the Shift indicator...usually,has a red tie wrap on it, the other 2 are the NSS. If you were to plug those to into each other with an adapter, you bypass the NSS, it would be the 2 in the harness, not the 2 from the shifter. The other similar switch In That area is the is on the ebrake lever...it sends the signal to light the red brake lamp on the dash....

 

[2w091]

The symptoms are:
When the vehicle is left out in the cold after use, then a start is attempted, it won't turn over and smoke comes from under the trans shifter. I drove it for three days straight, left it Putin the cold for four hours and it did it again.
after I put in the garage and put a charger on it, it starts right up.

There is no evidence of any arcing outside the rubber boot of the shifter assembly. When put in D it will not start, I disconnected the two 14 connectors and it would'nt turn over.
I'd like to disable or bypass the switch.
sorry for any typos, I'm on my phone.

 

[Retiredwarhorses]

Do not bypass the switch....it's there for your safety and everyone around you.
bypassing the switch allows the truck to be started in gear...if there is smoke? Something burned or is buring.
find it...fix it....

 

[2w091]

We plan on finding/fixing ASAP, the lamp for the shifter has never worked, I'm wondering if that's what is shorting out since the NSS seems to work. Either way we'll get it fixed, the weather has put us in a bind for a quick fix. I've got the pages and figures to do the work from the -20.
On the up side the vehicle has been a hammer in all this heavy snow, I've been getting cars out of the ditch and getting where others can't go. This was the intent on gettting the vehicle in the first place.
Thanks again for all the advice!
-Come on Spring................