blowing fuses
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blowing fuses
I have a 1978 F-250 that keeps blowing the instrument panel fuse. Is this most likely the board on the cluster or a wire? The instrument panel light is the only thing not working. The gauges and blinkers work fine.
Cargo Master
Joined: Jul 2005
Posts: 2,309
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From: Kansas
if that fuse is blown there should be other lamps affected (the one above the wiper/headlight switch, gear indicator if you have an automatic, AC/heater illumination, ashtray light and factory radio illumination) so the problem could be with any of those...
Laughing Gas
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From: S.E. Louisiana;so far USA
Lead Driver
Joined: Jul 2017
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From: San Jose, CA
When you say cluster and gauges as if they're separate, that's odd. Maybe you will have to pull it out to see if the circuit film has been modified with some kind of bypass. If so it must be an odd one, rather than fixing the original issue it just got bypassed. Maybe so long ago that it was before, or they just didn't know replacement circuit boards were available.
The gauge functions and turn signal indicators would not be effected, since they're not on the same circuit as the cluster illumination.
Still, just to clarify, the gauges that still have lights are the ones inside the cluster. Correct? And not some additional gauges mounted to the dash somewhere else?
Sorry if I'm not seeing the obvious. But it's a bit confusing.
Thanks
Paul
The gauge functions and turn signal indicators would not be effected, since they're not on the same circuit as the cluster illumination.
Still, just to clarify, the gauges that still have lights are the ones inside the cluster. Correct? And not some additional gauges mounted to the dash somewhere else?
Sorry if I'm not seeing the obvious. But it's a bit confusing.
Thanks
Paul
Lead Driver
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From: San Jose, CA
Ok, then it does sound as if there is a short somewhere. Perhaps a deteriorating circuit film on the back of the cluster, or a frayed wire somewhere along the line.
Since the power comes FROM the headlight switch, I don't think the short would be in the switch, or in-between the switch and the fuse. It must be in-between the fuse and the lamps.
The fuse is being overloaded, so it's either a short or as you said someone may have added a component to the circuit that is too much for the fuse.
But thinking about it, what are the fuses rated that are going in to the socket? I think they used to be about 5a on the old trucks that only had a few light bulbs, but your '78 would have quite a few more like dlburch was saying. Maybe the fuse rating for the '78 is supposed to be higher and the PO put in a too-small fuse?
Have you had the truck for awhile and it just started doing this? Or are you a newer owner and it's been doing this since you got the truck?
Paul
Since the power comes FROM the headlight switch, I don't think the short would be in the switch, or in-between the switch and the fuse. It must be in-between the fuse and the lamps.
The fuse is being overloaded, so it's either a short or as you said someone may have added a component to the circuit that is too much for the fuse.
But thinking about it, what are the fuses rated that are going in to the socket? I think they used to be about 5a on the old trucks that only had a few light bulbs, but your '78 would have quite a few more like dlburch was saying. Maybe the fuse rating for the '78 is supposed to be higher and the PO put in a too-small fuse?
Have you had the truck for awhile and it just started doing this? Or are you a newer owner and it's been doing this since you got the truck?
Paul
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Ok, then it does sound as if there is a short somewhere. Perhaps a deteriorating circuit film on the back of the cluster, or a frayed wire somewhere along the line.
Since the power comes FROM the headlight switch, I don't think the short would be in the switch, or in-between the switch and the fuse. It must be in-between the fuse and the lamps.
The fuse is being overloaded, so it's either a short or as you said someone may have added a component to the circuit that is too much for the fuse.
But thinking about it, what are the fuses rated that are going in to the socket? I think they used to be about 5a on the old trucks that only had a few light bulbs, but your '78 would have quite a few more like dlburch was saying. Maybe the fuse rating for the '78 is supposed to be higher and the PO put in a too-small fuse?
Have you had the truck for awhile and it just started doing this? Or are you a newer owner and it's been doing this since you got the truck?
Paul
Since the power comes FROM the headlight switch, I don't think the short would be in the switch, or in-between the switch and the fuse. It must be in-between the fuse and the lamps.
The fuse is being overloaded, so it's either a short or as you said someone may have added a component to the circuit that is too much for the fuse.
But thinking about it, what are the fuses rated that are going in to the socket? I think they used to be about 5a on the old trucks that only had a few light bulbs, but your '78 would have quite a few more like dlburch was saying. Maybe the fuse rating for the '78 is supposed to be higher and the PO put in a too-small fuse?
Have you had the truck for awhile and it just started doing this? Or are you a newer owner and it's been doing this since you got the truck?
Paul
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From: The Shenandoah Valley
Mine gradually faded until this one night, I noticed that they would not even light. Like boiling a live lobster .... Was just the instrument illumination lamps. Fix was to clean the rheostat windings (looks like a coil spring, rotates with shaft) and wiper (rubs the spring to vary voltage to the instrument illumination lamps ...and the end contact that lights the dome light) on the head light switch. They are exposed, once you have the switch out and on the bench. Much brighter now.
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