Gauge fuse
Thread Starter
Racer
Joined: Apr 2008
Posts: 333
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From: Portage Michigan
Gauge fuse
OK, last Thursday my gauge fuse blew, I replaced it and it was fine until I was on my way to work Friday, it blew again. I replaced it yet again during my lunch break and it was doing fine, until This past Thursday. It blew of course and I replaced it and of course it blew again, but now it seems to blow on start up. Does any one have any ideas as to what could be causing this? Any common problems, ect.? To my knowledge, no other fuse(s) have blown. Oh, and its a 1981.
Melting Slicks
Joined: Dec 2006
Posts: 2,669
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From: Kingston Ontario
You need to check the wiring on that circuit and you will probably find you have a wire that was swinging loose and grounded, causing the initial short and was OK until the car movement caused the wire to again move and contact where it shouldn't have.
Race Director
Joined: May 2006
Posts: 16,528
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From: Dayton, Ohio
My first guess would be the courtesy light delay timer.That will be easy to unplug and remove from the circuit.
That circuit has a lot of things on it.
On second thought you do mean the gauge fuse not the inst lamp fuse.
That circuit has a lot of things on it.
On second thought you do mean the gauge fuse not the inst lamp fuse.
Thread Starter
Racer
Joined: Apr 2008
Posts: 333
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From: Portage Michigan
Yes, it is the gauge fuse. And on the note that the headlight switch being able to cause this to happen, mine is bad, when you turn the head lights on the dash lights don't come on and the buzzer for when you turn the car off and leave the lights on doesn't work.
Race Director
Joined: May 2006
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From: Dayton, Ohio
Le Mans Master
Joined: Jan 2006
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From: Wilmington DE, Drive it like you stole it, 68 327 4 speed coupe
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Le Mans Master
Joined: Jan 2006
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From: Wilmington DE, Drive it like you stole it, 68 327 4 speed coupe
as far as the gauges themselves, the ammeter (68) taps directly into the charging circuit for power, and the temp gauge gets +12v from a switched source, and Neg from the sending unit, so both of these will function even if the gauge fuse is blown
The wiring diagram can be tough to read but if you follow batt power to the HL switch you can trace the path I am talking about
Last edited by sweethence; Oct 8, 2008 at 09:21 AM.
Race Director
Joined: May 2006
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From: Dayton, Ohio
OK, last Thursday my gauge fuse blew, I replaced it and it was fine until I was on my way to work Friday, it blew again. I replaced it yet again during my lunch break and it was doing fine, until This past Thursday. It blew of course and I replaced it and of course it blew again, but now it seems to blow on start up. Does any one have any ideas as to what could be causing this? Any common problems, ect.? To my knowledge, no other fuse(s) have blown. Oh, and its a 1981.
depends on the year what it was called, on my 68 its "gauges" and refers to the gauge cluster powered within the same circuit. As memory serves, while the gauges lamps, clock, marker and tail lamps are on the same circuit running through the headlight switch with direct battery power, within this circuit, there are independent fuses for the gauges vs the external lamps.
as far as the gauges themselves, the ammeter (68) taps directly into the charging circuit for power, and the temp gauge gets +12v from a switched source, and Neg from the sending unit, so both of these will function even if the gauge fuse is blown
The wiring diagram can be tough to read but if you follow batt power to the HL switch you can trace the path I am talking about
as far as the gauges themselves, the ammeter (68) taps directly into the charging circuit for power, and the temp gauge gets +12v from a switched source, and Neg from the sending unit, so both of these will function even if the gauge fuse is blown
The wiring diagram can be tough to read but if you follow batt power to the HL switch you can trace the path I am talking about
Le Mans Master
Joined: Jan 2006
Posts: 8,319
Likes: 7
From: Wilmington DE, Drive it like you stole it, 68 327 4 speed coupe
Okey Doke, missed that tid bit
Definately need to see an 81 wiring diagram while I doubt that are any major chages to the main Batt power circuit throught the HL switch (since when your turn the HL on you get the HL's the guage lights, tail and marker lamps). there are no doubt mods to the dash wiring harness to support differences in the dash, switches and instrumentation.
I would get a wiring diagram and begin to trace the circuits to fully understand your years wiring its defintely educational
Last edited by sweethence; Oct 7, 2008 at 10:16 AM.
Race Director
Joined: May 2006
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From: Dayton, Ohio
He states above the dash lights dont work...that can be a blown "inst lamp fuse" not a bad switch.He says the buzzer for the headlights doesnt work...the buzzer wont work if the "gauges fuse" is blown,which it is.
He could just unplug the headlight switch to see if that clears up his blowing of the "gauge fuse". I doubt it because I dont believe there is any connection between the headlight circuit,dash light circuit and the gauge fuse circuit.
Le Mans Master
Joined: Jan 2006
Posts: 8,319
Likes: 7
From: Wilmington DE, Drive it like you stole it, 68 327 4 speed coupe
I'm not convinced his headlight switch is bad and their 50 bucks +.
He states above the dash lights dont work...that can be a blown "inst lamp fuse" not a bad switch.He says the buzzer for the headlights doesnt work...the buzzer wont work if the "gauges fuse" is blown,which it is.
He could just unplug the headlight switch to see if that clears up his blowing of the "gauge fuse". I doubt it because I dont believe there is any connection between the headlight circuit,dash light circuit and the gauge fuse circuit.
He states above the dash lights dont work...that can be a blown "inst lamp fuse" not a bad switch.He says the buzzer for the headlights doesnt work...the buzzer wont work if the "gauges fuse" is blown,which it is.
He could just unplug the headlight switch to see if that clears up his blowing of the "gauge fuse". I doubt it because I dont believe there is any connection between the headlight circuit,dash light circuit and the gauge fuse circuit.
Just out of curiosity DW if HL, dash lights, marker lamps and tail lamps all get 12 volts bat power tied through the HL switch (as evidence that they come on at the same time) why dont you beleive they are on the same circuit?)
I with you now on the guages fuse seprate from the "inst lamp fuse" BTW, you got me thinking and i went back to my wiring diagram and stuck my head under the dash and sure as shootin I found it on mine, and it is a small Littel jobber, I stand corrected
and thanks :lol
anyone got an 81 schematic handy
If the headlight switch was bad, then depending on why its possible that not only would his guage lights be out, but his marker lamps and tail lamps as well, (brake lights would still work) this is what happened in my case. Now also on the HL switch, is a potentiometer that controls the brightness of the guage lights, ( I hope he just doesnt have it turned all the way low) if this part of the swithch has gone bad, but the rest of the swith is OK it may be possible to see just the guage lights not working and possibly the blown fuse condition he is seeing.
I love chasing down electrical gremlins :lol
cheers
tim
Last edited by sweethence; Oct 10, 2008 at 08:15 AM.
