Engine/Transmission (1994 - 1998) Park Neutral Switch Keeps Failing?

[norcalram]

SO the great state of california in requiring our trucks to now be smoged, is causing me more headaches. I failed smog on monday because my parl/neutral swich had gone out last year, so I just bypassed it. I put in new $30 switch and check enging light went out and truck fired right up. Went out today, light was back on! Fluid level shows ok, but when i pulled the switch some leaked out. Is the fluid to high and not supposed to cover the switch? could that be what is causing them to go out?

 

[Missouri Mule]

Is it a "Ball switch" ? On my Back-up switch which is a Ball switch, gets trans fluid in it all the time.

What causes my switch to go out is unseen tarnish build up on the connectors/pins/terminals. I spray the switch connectors out with a contact cleaner. I use CRC brand from Home Depot. I spray the connectors out with the lubricating one first then I use the Drying one after I let it sit 5 minutes. Brings back my Back-up Switch every time, so far.

 

[B.G. Smith]

Next time you have the pan off, check the little rail on the shift tower shaft to the valve body and see if it is ok. On the 727 transmissions there was a little strip of hard plastic on the rail and it would sometimes disintegrate with age. bg

 

[Bob4x4]

Are you sure that is the only reason for the smog fail?

Water injection will also be a fail

 

[norcalram]

I pulled the injection before i went in. the tech said if it wasn't for the dash light, I would have passed. The old switch was pretty gummed up and didnt move too freely, but i only had the new switch in less than 24 hours before the light came back on. the only change between the truck not starting and the light coming back was me topping off the fluid to replace what had come out.

 

[Bob4x4]

It is normal for ATF to run out when you remove
The neutral safety switch. Do you know the Dtc
That turned the light on?are we talking about a
12 or24vslve truck?

 

[norcalram]

Thats what i'm wondering about with the fluid level. the switch lies just above the pan, but it also doesn't have a washer or seal. none leaks out, but anout 1/2 a quart drains when i pull it. The dtc is 1899 which is the switch. I just bypassed it in the relay so the truck will start as the switch provides the ground in the starting circuit. I think i"ll probably drain fluid to below the switch and see if that helps. It will leave it a little low on the stick but not severly low?.

 

[Bob4x4]

There should indeed be a seal on the switch I would not assume the code is just the switch.

Possible causes,switch,wiring,mechanical trans problem or pcm OR YOUR ADD ON SWITCH

 

[norcalram]

Yeah, my other thought would be wiring between the switch and the pcm. I didn't add on a switch, I just grounded the term in the relay that that switch grounds when activated. Just a short wire from the power center to the firewall as a temp fix. it's a helpful wire to leave there, cause if that switch ever goes out on the road, the truck will not start. I ereased the code tonight and it has stayed off through several key cycles, if it comes back on tomorrow, I'll pull the switch again, clean it up, not top off the trans fluid and check the wiring between the trans and the pcm.