dash light dimmer circuit

[blackagatha]

SO I attempted to figure out why my dash lights dont dim. I first inspected my juvenile attempt at wiring and determined that I did in fact utilize the original circuit for the dash lights. I discovered that my thought that I may have patched into the tail light circuit was also correct though, I had connected the tach light and shifter illuminator to that... WHY???? I DONT KNOW...

so anyway, I connected the tach and shifter where they should have been, and found an inline fuse holder with the same colored wire as the dash light circuit that had a blown 2 amp short fuse in it. I changed the fuse. still no dim. and because all the wiring is obscured by 45 year old electrical tape factory looms, it is impossible to trace the run of the wires and understand the circuit by examination. I COULD cut off the tape, but it would be instant bird nest.... worse than I already got...

Dad says he thinks the rheostat may not be contacting or something, but I am at a total loss at how this circuit is supposed to work. schematic anyone?

I always assumed that the rheostat was between the hot source and the lights, he seems to think that the rheostat is like a draw on the circuit in parallel with the lights maybe? and I dont understand what is going on with the fuse, new fuse changed nothing, and blown fuse = lights work?????

[Lowell]

Are you sure the rheostat is good? mine was burnt out and i had to replace the complete switch.

[Ford4jack]

BA if you go to the fordtruk.com link here there's some wiring diagrams for the 64 model trucks in the tech section that migh be of help to you.

Between that and dropping your light switch out for a look see at the rheostat you should be able to get it working.

[bertha66]

On my truck, I pulled the rheostat out of the switch, cleaned it with some very fine sand paper and reinstalled it. Also cleaned the contact point that rides on the rheostat. Worked out good.

[blackagatha]

it is a BRAND NEW Motorcraft switch from Dennis Carpenter. It is not corroded. only thing thing I can think of is maybe the contactor doesnt rub hard enough.