popping fuses?? Help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Suicide-D · 11-16-2003, 12:55 PM

Ok I'm getting a little frustrated with my 70. I am popping the dash/tail light fuse after a short drive. I can sit in the drive way idling for as long as I want, doing everything (jumping on th bumper, blaring the radio, honking the horn, stomping the brakes, leaving the lights on...)I would be doing driving and it doesn't pop the fuse. drive it around the block and pow. This is only with the headlights on. If i leave them off it is fine.

Think my headlight switch is drawing too much?

any ideas?

I should go buy stock in Buss fuse company if this keeps up.

Thanks,
Darryl

Class of 69 · 11-16-2003, 01:06 PM

It sounds like you have a bare wire touching a ground when you drive it. Odd that it only happens with the headlights on, tho. It may be the switch. That's the only common link I can think of, or find in the wiring diagram. An old repair trick is to replace the fuse with a bolt, and wait till you see smoke...Pull the bolt quick, and look for the melted insulation. A little risky, but effective.

my new 72 · 11-16-2003, 01:07 PM

I think the switch is pulling too much and the voltage regulator is over compensating and blowing the fuse.

Suicide-D · 11-16-2003, 01:17 PM

i think it's the switch also... I 'll go get one and see... be right back.

jhwkns · 11-16-2003, 01:20 PM

I had a similar problem once... Check the grounds on your headlights

Class of 69 · 11-16-2003, 01:29 PM

Good Point!! Overvoltage feeding back to the switch, and blowing the fuse. Very possible.

cdowns · 11-16-2003, 01:39 PM

now's a good time to check the wires that run down the driverside framerail to the rearlights it's not uncommon for them to flap around and shortout due to insullation dryrotting

Longhorn Man · 11-16-2003, 01:57 PM

I say it is more likely that you have a bare wire going to the tail lights or the front parking lights. First place I'd be looking is under the rear bumper where the trailer harness is/would be. Over the years it is not uncommon to have a few harnesses spliced in.
Look at the brown wire on that harness...that'll be the problematic wire.

Suicide-D · 11-16-2003, 02:13 PM

Ok... I'm going under the truck... it is not the switch. I have only popped 15 fuses looking for this...

Suicide-D · 11-16-2003, 05:36 PM

it was in the rear harness, that whole thing was a mess...it now has new wiring from the firewall all the way back to the bulbs.

Class of 69 · 11-16-2003, 07:36 PM

Glad you found it. I was initially suspect of the rear harness too...but you threw in a curve ball with it only happening while the headlights were on. The headlights shouldn't matter with a harness short in the rear.

jugernot · 11-16-2003, 07:42 PM

must have a ground some where thats shorting the fuse

Locutus · 11-17-2003, 12:01 AM

when the headlights are on so are the tail lights. I had a short in a trailer light that every time we hooked up the trailer it would pop the dash/taillight fuse. Gave me a headache tracing it down too.

sneakysnake · 11-17-2003, 12:41 PM

May help the next guy. you can take alligator clips and hook to a 12 volt bulb, remove the fuse and place on each terminal of the fuse holder as long as there is a short the bulb will be brightly lit
place where you can see it and get to wiggling wires. Make sure the switch is on .

RussTburb · 11-17-2003, 02:18 PM

Not trying to start anything but I thought I should point out that it is impossible for a bad ground to blow a fuse. Fuses blow due to too much amps (current) bad ground = resistance (less current). ohms law says that as reisistance increases voltage and amps decrease. Again just trying to help and I'm not trying to steele the thread. Glad you found your problem!

lukecp · 11-17-2003, 05:49 PM

I had a very identical problem once....a wire in my tailight harness had worn through the insulation and was grounding out on the frame, and blowing out my dash light/tailight fuse.

RussTburb, i *think* the reason a bad ground blows a fuse has something to do with the wire shorting out....since both the + and - currents are touching each other. I think this would draw more current through the wire, and poof! there goes the fuse. You have ohms law correct...as resistance increases, voltage and amps go down. I am pretty sure that the short would draw alot of current though.....something like that anyway

'70 C/10 SS500 · 11-17-2003, 05:49 PM

I don't know if this will help any, but here goes anyway. My truck would blow the taillight fuse CONSTANTLY! It only did it with the headlights on also. I carried 3 boxes of 5 at all times! I tore apart the dash and looked at the printed circuit for clues, nothing wrong there. I replaced my headlight switch to no avail. I completely overhauled my column wiring harness and turn signal mechanism without any luck either, still blowing fuses randomly but frequently. I traced the wiring from the pedal to fuse block,- fuse block to taillights,- dissasembled the taillights and checked things completely, but everything was good. Still no answers. Well, one DAY I was getting out of my truck, pulled the detachable face of my CD played, stashed it under the seat as always and shut the door.....CRUNCH! I had closed the door on the CD player (face) and it smashed it pretty good, thanks to good 'ole Flint steel! My CD played/RADIO has never worked since, but I tell you what, I've never replaced another fuse since either!

Shamefully, I've never corrected the problem. Since I've never turned the radio on since, the symtoms are completely gone. Unfortunately, the CAUSE undoubtedly still exists.

Sorry for the long post, but it's kind of an interesting story, and hey, it's been a while since I posted too! Hope it helps someone else. I hate electrical gremlins!

my new 72 · 11-17-2003, 06:23 PM

When saying you have a "Bad Ground", what is meant is that there is a ground somewhere on the chassis that is not connected and not letting the current flow through the loop like it should be. TYo say that you have a wire that is "Grounding Out", then that means that you have a hot wire that is frayed or exposed in some other way that is touching to ground and shorting out. Having a "Bad Ground" will not blow a fuse, but having a wire that is "Grounding Out" will. Ohms law is a bit too technical for this type of problem, if fuses are going "POP", then there is a problem on the HOT side.

RussTburb · 11-17-2003, 07:16 PM

[QUOTE]Originally posted by '70 C/10 SS500
[B]CRUNCH! I had closed the door on the CD player (face) and it smashed it pretty good, thanks to good 'ole Flint steel! My CD played/RADIO has never worked since, but I tell you what, I've never replaced another fuse since either!

It has happened to all of us, As a Tech I have found more wiring problems related to stereo installtion! frayed wires loose wires, wires tapped in to the wrong circuit, radios causing new computer cars to stop running!! One question I always ask customers now is "When did you notice this problem?" Always a good place to start!

Totally aggree with you My new 72 sorry to over complicate things! Its a nasty habbit of mine!lol

11-16-2003, 12:55 PM	#1
Suicide-D Registered User Join Date: Jan 2001 Location: Katy, TX...but the love of my life resides in Dublin,OH. Posts: 1,408	popping fuses?? Help Ok I'm getting a little frustrated with my 70. I am popping the dash/tail light fuse after a short drive. I can sit in the drive way idling for as long as I want, doing everything (jumping on th bumper, blaring the radio, honking the horn, stomping the brakes, leaving the lights on...)I would be doing driving and it doesn't pop the fuse. drive it around the block and pow. This is only with the headlights on. If i leave them off it is fine. Think my headlight switch is drawing too much? any ideas? I should go buy stock in Buss fuse company if this keeps up. Thanks, Darryl

11-16-2003, 01:06 PM	#2
Class of 69 Registered User Join Date: Mar 2003 Location: Stillwater MN Posts: 1,166	It sounds like you have a bare wire touching a ground when you drive it. Odd that it only happens with the headlights on, tho. It may be the switch. That's the only common link I can think of, or find in the wiring diagram. An old repair trick is to replace the fuse with a bolt, and wait till you see smoke...Pull the bolt quick, and look for the melted insulation. A little risky, but effective. __________________ 69 GMC K10 ..some restoration required....still..

11-16-2003, 01:07 PM	#3
my new 72 faster, faster, faster Join Date: Dec 2001 Location: Houston ,Texas ,USA Posts: 1,354	I think the switch is pulling too much and the voltage regulator is over compensating and blowing the fuse. __________________ I'm going to Law School, wanna debate? It's good practice.

11-16-2003, 01:20 PM	#5
jhwkns Registered Cruiser Join Date: May 2002 Location: Las Vegas NV Posts: 2,230	I had a similar problem once... Check the grounds on your headlights __________________ I intend to live forever. So far, so good.

11-16-2003, 01:29 PM	#6
Class of 69 Registered User Join Date: Mar 2003 Location: Stillwater MN Posts: 1,166	Good Point!! Overvoltage feeding back to the switch, and blowing the fuse. Very possible. __________________ 69 GMC K10 ..some restoration required....still..

11-16-2003, 01:17 PM	#4
Suicide-D Registered User Join Date: Jan 2001 Location: Katy, TX...but the love of my life resides in Dublin,OH. Posts: 1,408	i think it's the switch also... I 'll go get one and see... be right back.

11-16-2003, 01:39 PM	#7
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	now's a good time to check the wires that run down the driverside framerail to the rearlights it's not uncommon for them to flap around and shortout due to insullation dryrotting __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

11-16-2003, 01:57 PM	#8
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	I say it is more likely that you have a bare wire going to the tail lights or the front parking lights. First place I'd be looking is under the rear bumper where the trailer harness is/would be. Over the years it is not uncommon to have a few harnesses spliced in. Look at the brown wire on that harness...that'll be the problematic wire.

11-16-2003, 02:13 PM	#9
Suicide-D Registered User Join Date: Jan 2001 Location: Katy, TX...but the love of my life resides in Dublin,OH. Posts: 1,408	Ok... I'm going under the truck... it is not the switch. I have only popped 15 fuses looking for this...

11-16-2003, 05:36 PM	#10
Suicide-D Registered User Join Date: Jan 2001 Location: Katy, TX...but the love of my life resides in Dublin,OH. Posts: 1,408	thanks everyone... it was in the rear harness, that whole thing was a mess...it now has new wiring from the firewall all the way back to the bulbs.

11-16-2003, 07:36 PM	#11
Class of 69 Registered User Join Date: Mar 2003 Location: Stillwater MN Posts: 1,166	Glad you found it. I was initially suspect of the rear harness too...but you threw in a curve ball with it only happening while the headlights were on. The headlights shouldn't matter with a harness short in the rear. __________________ 69 GMC K10 ..some restoration required....still..

11-16-2003, 07:42 PM	#12
jugernot Life, Be In It..... Join Date: Oct 2003 Location: Novato, California Posts: 1,498	must have a ground some where thats shorting the fuse

11-17-2003, 12:01 AM	#13
Locutus Registered User Join Date: Jan 2003 Location: Santa Fe, Texas Posts: 250	when the headlights are on so are the tail lights. I had a short in a trailer light that every time we hooked up the trailer it would pop the dash/taillight fuse. Gave me a headache tracing it down too.

11-17-2003, 12:41 PM	#14
sneakysnake It's a catastrophic success. Join Date: Jan 2003 Location: Oklahoma Posts: 2,077	May help the next guy. you can take alligator clips and hook to a 12 volt bulb, remove the fuse and place on each terminal of the fuse holder as long as there is a short the bulb will be brightly lit place where you can see it and get to wiggling wires. Make sure the switch is on .

11-17-2003, 02:18 PM	#15
RussTburb Registered User Join Date: Mar 2002 Location: Blaine,Wa. U.S.A Posts: 261	Not trying to start anything but I thought I should point out that it is impossible for a bad ground to blow a fuse. Fuses blow due to too much amps (current) bad ground = resistance (less current). ohms law says that as reisistance increases voltage and amps decrease. Again just trying to help and I'm not trying to steele the thread. Glad you found your problem! __________________ "Red-heads not war-heads, Blondes, not bombs, Brunettes, not fighter jets!" Fligh of the Choncords 72 burb 3/4 ton 2wd 06 2500 suburban 8.1L 4x4 84 chev 4x4 diesel 96 Geo Metro with the 4cylbb, lol! Almost 300k just won't die! 89 Honda Civic, runs on the smell of an oily rag! 2008 Aerolite 26qs Travel Trailer (aka "THE BARN")



Register or Log In To remove these advertisements.

11-17-2003, 05:49 PM	#16
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	I had a very identical problem once....a wire in my tailight harness had worn through the insulation and was grounding out on the frame, and blowing out my dash light/tailight fuse. RussTburb, i think the reason a bad ground blows a fuse has something to do with the wire shorting out....since both the + and - currents are touching each other. I think this would draw more current through the wire, and poof! there goes the fuse. You have ohms law correct...as resistance increases, voltage and amps go down. I am pretty sure that the short would draw alot of current though.....something like that anyway __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

11-17-2003, 05:49 PM	#17
'70 C/10 SS500 Registered User Join Date: Jun 2003 Location: Chandler, AZ Posts: 130	Here goes nothin' I don't know if this will help any, but here goes anyway. My truck would blow the taillight fuse CONSTANTLY! It only did it with the headlights on also. I carried 3 boxes of 5 at all times! I tore apart the dash and looked at the printed circuit for clues, nothing wrong there. I replaced my headlight switch to no avail. I completely overhauled my column wiring harness and turn signal mechanism without any luck either, still blowing fuses randomly but frequently. I traced the wiring from the pedal to fuse block,- fuse block to taillights,- dissasembled the taillights and checked things completely, but everything was good. Still no answers. Well, one DAY I was getting out of my truck, pulled the detachable face of my CD played, stashed it under the seat as always and shut the door.....CRUNCH! I had closed the door on the CD player (face) and it smashed it pretty good, thanks to good 'ole Flint steel! My CD played/RADIO has never worked since, but I tell you what, I've never replaced another fuse since either! Shamefully, I've never corrected the problem. Since I've never turned the radio on since, the symtoms are completely gone. Unfortunately, the CAUSE undoubtedly still exists. Sorry for the long post, but it's kind of an interesting story, and hey, it's been a while since I posted too! Hope it helps someone else. I hate electrical gremlins! Last edited by '70 C/10 SS500; 11-17-2003 at 06:01 PM.

11-17-2003, 06:23 PM	#18
my new 72 faster, faster, faster Join Date: Dec 2001 Location: Houston ,Texas ,USA Posts: 1,354	When saying you have a "Bad Ground", what is meant is that there is a ground somewhere on the chassis that is not connected and not letting the current flow through the loop like it should be. TYo say that you have a wire that is "Grounding Out", then that means that you have a hot wire that is frayed or exposed in some other way that is touching to ground and shorting out. Having a "Bad Ground" will not blow a fuse, but having a wire that is "Grounding Out" will. Ohms law is a bit too technical for this type of problem, if fuses are going "POP", then there is a problem on the HOT side. __________________ I'm going to Law School, wanna debate? It's good practice.

11-17-2003, 07:16 PM	#19
RussTburb Registered User Join Date: Mar 2002 Location: Blaine,Wa. U.S.A Posts: 261	Re: Here goes nothin' [QUOTE]Originally posted by '70 C/10 SS500 [B]CRUNCH! I had closed the door on the CD player (face) and it smashed it pretty good, thanks to good 'ole Flint steel! My CD played/RADIO has never worked since, but I tell you what, I've never replaced another fuse since either! It has happened to all of us, As a Tech I have found more wiring problems related to stereo installtion! frayed wires loose wires, wires tapped in to the wrong circuit, radios causing new computer cars to stop running!! One question I always ask customers now is "When did you notice this problem?" Always a good place to start! Totally aggree with you My new 72 sorry to over complicate things! Its a nasty habbit of mine!lol __________________ "Red-heads not war-heads, Blondes, not bombs, Brunettes, not fighter jets!" Fligh of the Choncords 72 burb 3/4 ton 2wd 06 2500 suburban 8.1L 4x4 84 chev 4x4 diesel 96 Geo Metro with the 4cylbb, lol! Almost 300k just won't die! 89 Honda Civic, runs on the smell of an oily rag! 2008 Aerolite 26qs Travel Trailer (aka "THE BARN")

Register or Log In To remove these advertisements.