Dim Instrument panel lights

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putt@webtv.net - 07 Nov 2007 04:50 GMT

'81 F100....All the bulbs light, but are very dim. Rheostat works, in
that it will dim them even more to Off. I can' find a electrical
troubleshooter for this problem, so I'm at a loss. Advice appreciated.
Thanks

Dave S(Texas)

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david - 07 Nov 2007 10:25 GMT

On Tue, 06 Nov 2007 22:50:08 -0600, putt rearranged some electrons to say:

> '81 F100....All the bulbs light, but are very dim. Rheostat works, in
> that it will dim them even more to Off. I can' find a electrical
> troubleshooter for this problem, so I'm at a loss. Advice appreciated.
> Thanks
>
> Dave S(Texas)

worn-out rheostat in headlight switch.

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Jeff Strickland - 08 Nov 2007 01:26 GMT

My guess is the rheostat is toast. It should adjust the lights from bright
to dim, but it can fail and only adjust from dim to dimmer.

Talking about an '81 makes the light switch my first stop on the
troubleshooting parade.

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nospamtolipmeat@webtv.net - 09 Nov 2007 15:25 GMT

Thanks. I'm gonna check the rheostat voltage In/Out. Problem is: the
bulb at the AC/Heater function control and the cab light, are normal
bright. Same rheostat. I'm gonna do some electrical contact point
cleaning and check the ground to that assembly. Geez, 26yrs and now I'm
beginning to have problems... :)

Thanks

Dave S(Texas)

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Chuck - 09 Nov 2007 16:37 GMT

> Thanks. I'm gonna check the rheostat voltage In/Out. Problem is: the
> bulb at the AC/Heater function control and the cab light, are normal
[quoted text clipped - 5 lines]
>
> Dave S(Texas)

<snip> the bulb at the AC/Heater function control and the cab light, are
normal bright. Same rheostat <snip>

In that case check for the correct bulb numbers that are installed. I know
its obvious, but just in case.

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