head lights are on. Does anyone know why or where the switch is located? Any help would be great.

 

Give more info on what truck and trans you have, they are usually located on the trans somewhere. Sounds like ground issue or something of that nature.

 

Sorry. 92 w250 with a a518.

I looked at the trans and there was only one plug in that I could see and it had 3 wires.

I un pluged it and the truck would not start. I figured it was for the neutral safety switch.

 

Yup that 3 prong plug is the neutral safety switch, and reverse lights. Unplugging it will indeed affect your truck starting. You can try a new switch, if they are still on then there might be an addition switch on the column for the reverse lights?....I'm not too familiar with the wiring set-up on the 91.5-93's.

 

I will pull the switch tomorrow and try to bench test it.

19 years old I may just replace it and go from there.

 

It sounds like a bad ground to me like said above.

 

Where would I start to look for the bad grounds?

 

In the tail light harness on the back of the truck. What can happen is the tail light circuit will ground through the backup lights which in turn causes them to glo just the same as the taillights. I would look to see if the ground wire has broken off.

 

Great i'll check that out tomorrow.

Is there any other switching in the steering column or is the only switch at the trans.

 

No REVERSE-switch in the column, nor the shifter; the only switch is in the transmission itself.

The only possible cause for your situation is that already described = tail-lights seeking GROUND through the REVERSE bulbs.

 

Thanks guys. Saturday is my birthday and I can do what I want day.
So I will check out the rear grounds with my 12 pack.