Help! electrical gremlins - The 1947 - Present Chevrolet & GMC Truck Message Board Network

69heavychevy · 12-20-2007, 12:28 PM

for some reason the fuse that power my dash light keep blowing. i know the culprit but dont why it doing it. i have a 800 watt amp that i use to power all the speaker in my truck, two 4" tweeters, two 6x9, and a 10" sub. everything was find and dandy until i installed a sunpro tach. two week after the install i blew the first fuse. didnt think much of it. they kept blowing but i noticed it only does it when i have the headlights on and my stereo up loud. yes i understand that puts a good size load on the electrical system, but take in mind it had never done it before until i hooked up my tach. with the tach hooked up it would take seconds for the fuse to blow, unhooked will take minutes, and with headlights off wont blow. i tried putting a 10amp fuse, BIG!!!! mistake. i had never heard a sizzling sound followed by tons of smoke come from under the dash!!!

Luvlegs · 12-20-2007, 12:47 PM

I'd check all your grounds - you often see guys with big ol' monster cable to the amp and then a little 12 ga. ground wire... I like a nice big fat ground off the amp, grounded as close to it as possible. Can't say that's the issue but I'd start there. Might not have been from WHEN you installed the tach, but it may have been starting sooner and happened to go right after the tach install.

68K20 x Drill · 12-20-2007, 12:49 PM

Give the amp its own fused wire from the battery. I don't think your 40 year old ignition switch wants to handle that much power.

Luvlegs · 12-20-2007, 12:56 PM

AND put it on a relay.

69heavychevy · 12-20-2007, 12:57 PM

i have a 4 gauge wire coming from the battery to power the amp. i have 2 ft. 4 gauge grounding the amp. i have the head unit powered through the fuse box, and the tach as well. for now i just have to drive with the stereo blasting and no dash panel lights

, couldnt have it the other way.

Longhorn Man · 12-20-2007, 01:30 PM

when your dash light fuse blows, you also have no tail lights or brake lights.

I highly doubt your stereo has anything to do with it. If it goes to the battery, then there should be no reason in the woirld it would do anything to the fuse in the fues box.

68K20 x Drill · 12-20-2007, 02:16 PM

I have seen a few cars do this when the chassis of the aftermarket stereo is not grounded with its own wire. Might be something to try.

69heavychevy · 01-09-2008, 06:26 AM

i finally figured out my problem, im a penny pincher!!! the root of my problem was the cheap sony headunit i was using. it didnt have the needed a/v outputs to run a amp so i used a convertor box instead. so not only was the amp pulling juice from the battery but the headunit as well when i would crank it up. so i took the cheapy sony out and for now put in my 8 year old trusty alpine w/ 3 a/v outputs and now everything is back to normal.

12-20-2007, 12:28 PM	#1
69heavychevy Registered User Join Date: Jan 2007 Location: Garland,TX Posts: 431	Help! electrical gremlins for some reason the fuse that power my dash light keep blowing. i know the culprit but dont why it doing it. i have a 800 watt amp that i use to power all the speaker in my truck, two 4" tweeters, two 6x9, and a 10" sub. everything was find and dandy until i installed a sunpro tach. two week after the install i blew the first fuse. didnt think much of it. they kept blowing but i noticed it only does it when i have the headlights on and my stereo up loud. yes i understand that puts a good size load on the electrical system, but take in mind it had never done it before until i hooked up my tach. with the tach hooked up it would take seconds for the fuse to blow, unhooked will take minutes, and with headlights off wont blow. i tried putting a 10amp fuse, BIG!!!! mistake. i had never heard a sizzling sound followed by tons of smoke come from under the dash!!!

12-20-2007, 12:47 PM	#2
Luvlegs Registered User Join Date: Sep 2005 Location: Smith Mountain Lake Virginia Posts: 1,537	Re: Help! electrical gremlins I'd check all your grounds - you often see guys with big ol' monster cable to the amp and then a little 12 ga. ground wire... I like a nice big fat ground off the amp, grounded as close to it as possible. Can't say that's the issue but I'd start there. Might not have been from WHEN you installed the tach, but it may have been starting sooner and happened to go right after the tach install. __________________ "A cat will almost always blink when hit between the eyes with a ball peen hammer" (you don't always have to state the obvious) Wear your PPE! You can eat with false teeth but you can't see with a false eye. 1959 Studebaker Silverhawk 350/400 1972 C10 L6 3OTT 2005 F350 - Built - whew!

12-20-2007, 12:49 PM	#3
68K20 x Drill Registered User Join Date: Apr 2007 Location: Freedom CA Posts: 488	Re: Help! electrical gremlins Give the amp its own fused wire from the battery. I don't think your 40 year old ignition switch wants to handle that much power. __________________ 68 Chevrolet k20 Longbed 350 SM465/205, Dana 44, 14bolt, Power steering, Power Disk Brakes, 35" BFGs. 84 Chevrolet Suburban K20 6.2 Banks turbo TH400/NP208 Now with G80 68 GMC C20 Parts? Truck And a few cars

12-20-2007, 12:56 PM	#4
Luvlegs Registered User Join Date: Sep 2005 Location: Smith Mountain Lake Virginia Posts: 1,537	Re: Help! electrical gremlins AND put it on a relay. __________________ "A cat will almost always blink when hit between the eyes with a ball peen hammer" (you don't always have to state the obvious) Wear your PPE! You can eat with false teeth but you can't see with a false eye. 1959 Studebaker Silverhawk 350/400 1972 C10 L6 3OTT 2005 F350 - Built - whew!

12-20-2007, 12:57 PM	#5
69heavychevy Registered User Join Date: Jan 2007 Location: Garland,TX Posts: 431	Re: Help! electrical gremlins i have a 4 gauge wire coming from the battery to power the amp. i have 2 ft. 4 gauge grounding the amp. i have the head unit powered through the fuse box, and the tach as well. for now i just have to drive with the stereo blasting and no dash panel lights, couldnt have it the other way. Last edited by 69heavychevy; 12-20-2007 at 12:57 PM.

12-20-2007, 01:30 PM	#6
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Re: Help! electrical gremlins when your dash light fuse blows, you also have no tail lights or brake lights. I highly doubt your stereo has anything to do with it. If it goes to the battery, then there should be no reason in the woirld it would do anything to the fuse in the fues box.

12-20-2007, 02:16 PM	#7
68K20 x Drill Registered User Join Date: Apr 2007 Location: Freedom CA Posts: 488	Re: Help! electrical gremlins I have seen a few cars do this when the chassis of the aftermarket stereo is not grounded with its own wire. Might be something to try. __________________ 68 Chevrolet k20 Longbed 350 SM465/205, Dana 44, 14bolt, Power steering, Power Disk Brakes, 35" BFGs. 84 Chevrolet Suburban K20 6.2 Banks turbo TH400/NP208 Now with G80 68 GMC C20 Parts? Truck And a few cars

01-09-2008, 06:26 AM	#8
69heavychevy Registered User Join Date: Jan 2007 Location: Garland,TX Posts: 431	Re: Help! electrical gremlins i finally figured out my problem, im a penny pincher!!! the root of my problem was the cheap sony headunit i was using. it didnt have the needed a/v outputs to run a amp so i used a convertor box instead. so not only was the amp pulling juice from the battery but the headunit as well when i would crank it up. so i took the cheapy sony out and for now put in my 8 year old trusty alpine w/ 3 a/v outputs and now everything is back to normal.



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