P1780 Park Neutral Position switch light (1 Viewer)

[Couch]

Hi all, I'm new to the forum, and a relatively new first time owner of a 97 FZJ80 - I bought it in December 2013. It's in pretty good shape for the most part and I'm really enjoying it so far. It does have a few minor things to work on, and I'm learning a lot from reading this group.

I am having one issue that I haven't been able to resolve - check engine light came on about a week ago - code was P1780 - park neutral position switch. I unplugged the switch, checked continuities, all seemed to be as they should, plugged it back in and the cel went out. So I figured, probably a bad connection in the plug? A couple days ago the light came back on, so I tried unplugging, cleaning, and reconnecting the plug - this time the light stayed on. Yesterday, the light went out without any action by me, other than starting the engine. It hasn't caused starting problems, only the engine light.

I understand the trouble shooting procedure for this code, but I don't really know how to track down what seems to be an intermittent fault like this. I'd prefer not to just replace the switch without knowing that's the source of the trouble. Anyone have any suggestions?

Thanks, Eric

 

[Timpanogos Slim]

Isn't that switch adjustable? Pie shaped thing on the side of the transmission, loosen the screws and adjust slightly?

I've also heard of people disassembling it, cleaning it, re-packing with silicone, and reinstalling, I think.

Could also be the junction in the wire harness over by the starter. I'm pretty sure this is why mine just does not work at all.

 

[Couch]

It looked more rectangular to me, about the size of a pack of cigarettes but thinner, but yes I think it is adjustable. When I checked it all I did was check that there was continuity between the terminals that were supposed to have it - that all checked out. Maybe I should have also checked if there was continuity where where it shouldn't be or jiggling the linkage to see if the adjustment is off. The thing is kind of awkward to work on, plug points straight up, can't see into it at all, I can only fit one hand up there to hold the test leads.

To me the switch didn't look obviously able to be openned for cleaning, but it might be possible.

Also it is possible that the problem is somewhere in the wiring and it was just a coincidence that the light went out after I monkeyed with the switch.

Thanks for your help!

Isn't that switch adjustable? Pie shaped thing on the side of the transmission, loosen the screws and adjust slightly?

I've also heard of people disassembling it, cleaning it, re-packing with silicone, and reinstalling, I think.

Could also be the junction in the wire harness over by the starter. I'm pretty sure this is why mine just does not work at all.

 

[Timpanogos Slim]

maybe I'm thinking of a different device - i have a 94 so a completely different transmission. on the A442F it's basically a rotary knife switch with limited throw on the side of the transmission. I've heard both "neutral safety switch" and "park neutral switch".

I have no codes (obd1) but no reverse lighting, and i understand that if i give it any speed in reverse it will pop out of gear.