Instrument cluster lights don’t work.
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2nd Gear
Joined: Jul 2023
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Instrument cluster lights don’t work.
I have a 1985 F-250. It’s been sitting for a couple years due to me bein in the military until recently.
Recently I realized the instrument cluster lights and a/c control panel don’t light up when I turn the headlights on. All exterior lights work. So far I’ve replaced the fuse (even tho it was fine,) I’ve replaced the whole headlight switch and still nothing. Just a day ago I realized that when the instrument cluster is unplugged, the light for the a/c control panel comes on. But goes off as soon as the cluster is plugged back in. All the bulbs look fine. My next step was gonna be to replace the printed circuit board and voltage regulator. Other things I’ve check include, power to the instrument cluster lights on the wire harness, there’s power. I’ve even looked over the wiring harness itself and everything looks fine. Any help would be great. I would really love to get this truck road worthy again.
Recently I realized the instrument cluster lights and a/c control panel don’t light up when I turn the headlights on. All exterior lights work. So far I’ve replaced the fuse (even tho it was fine,) I’ve replaced the whole headlight switch and still nothing. Just a day ago I realized that when the instrument cluster is unplugged, the light for the a/c control panel comes on. But goes off as soon as the cluster is plugged back in. All the bulbs look fine. My next step was gonna be to replace the printed circuit board and voltage regulator. Other things I’ve check include, power to the instrument cluster lights on the wire harness, there’s power. I’ve even looked over the wiring harness itself and everything looks fine. Any help would be great. I would really love to get this truck road worthy again.
FTE Legend
Joined: Nov 2015
Posts: 30,974
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From: Angier, NC
Welcome to FTE
I know the switch has been replaced but have you turned the **** full left & right to see what happens?
I also know you tested for power at the plug if test light how bright was it or how many volts?
What is the volts at the fuse?
You say it lights at the HVAC panel what about the head light / wiper light?
If the above all checks out I think I would try a new circuit board.
Dave ----
ps are you using LED bulbs if so some only work when installed a certain way, turn them 180*
I know the switch has been replaced but have you turned the **** full left & right to see what happens?
I also know you tested for power at the plug if test light how bright was it or how many volts?
What is the volts at the fuse?
You say it lights at the HVAC panel what about the head light / wiper light?
If the above all checks out I think I would try a new circuit board.
Dave ----
ps are you using LED bulbs if so some only work when installed a certain way, turn them 180*
Lead Driver
Joined: Nov 2013
Posts: 7,184
Likes: 1,175
https://www.garysgaragemahal.com/1985-evtm.html
I'd suspect one of the bulbs in the instrument cluster is drawing too much power. Not bad enough to blow the fuse, but enough to draw down power to the rest of the circuit. Try removing all of the bulbs in the cluster and see what happens. Then reinstall the bulbs one at a time. I bet you will find one of them at fault.
Also, check the lights in the ash tray and wiper switch panel. They are on the same circuit.
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