Welcome! Please use the navigational links to explore our website.
PartsASAP LogoCompany Logo (800) 853-2651

Shop Now

   Allis Chalmers Case Farmall IH Ford 8N,9N,2N Ford
   Ferguson John Deere Massey Ferguson Minn. Moline Oliver

Attention Forum Users: On the 28th of December 2023 at 9:00am Central Time, we will be taking the forums down for maintenance while we prepare the new forums for your use. Please click here for more information.

Tool Talk Discussion Forum

OT - How to find an auto electrical short?

Welcome Guest, Log in or Register
Author 
Bobg

08-26-2005 06:42:36




Report to Moderator

My son has a 91 Acura Integra and the fuse that runs the dash lights and tail lights keeps blowing. It was working fine then out of the blue it started blowing fuses. What would be the best way to find it? I'm a kind of a loss since I'm not too familar with this sort of thing.

Thanks,
Bobg




[Log in to Reply]   [No Email]
Vinnie

09-04-2005 15:58:51




Report to Moderator
 Re: OT - How to find an auto electrical short? in reply to Bobg, 08-26-2005 06:42:36  
I had a similar problem on a 1979 Buick. It was my dad's car and since it happened while I was driving it, *I* must have caused it. It was a 20 amp fuse and a dead shorted circuit to ground. I decided to check all of the light sockets, thinking one of them has moisture or corrosion causing the fuse to blow. As I pulled the left rear light assembly out of its bumper opening, I noticed that they didn't leave much length on the harness to get to the bulbs for replacement. The sockets and bulbs were fine. As I was replacing the assembly, I noticed one wire in the taillight harness was pinched under one of the bumper mounting bolts, from the factory. After loosening the bolt, cutting out the pinched section and butt-splicing it back together, no short. I had to save the pinched piece of wire as "Exhibit A" in my defense that nothing I did while using the car caused this. Good Luck

-Vinnie

[Log in to Reply]  [No Email]
Chris Miller

09-02-2005 06:20:40




Report to Moderator
 Re: OT - How to find an auto electrical short? in reply to Bobg, 08-26-2005 06:42:36  
I'd also look at the trunk in the hinge area. Often the wiring for the tail and license plate lights runs across the hinge area down to the trunk lid, and the constant flexing causes the wiring to break the insulator or the entire wire.

Might have to open a protective loom to see this. If one or more are broken, consider rewiring them all (add in a little extra wire to make the splice not at the flex point).

Chris

[Log in to Reply]  [No Email]
RayP(MI)

08-28-2005 17:04:40




Report to Moderator
 Re: OT - How to find an auto electrical short? in reply to Bobg, 08-26-2005 06:42:36  
Had one of those a few years back. 'Bout drove me crazy! Finally found where wiring harness was routed over a sharp piece of metal under the dash, and had finally worn thru - shorted out only tail lites. Took me a long time to find that one! Just kept working over harness looking for trouble until I found it. At that time almost all grounds were through the body. Now, the wiring carries it's own ground wire as well. Helps if you can locate a factory shop manual which shows where wiring harnesses run, and where you can unhook various sections of it.

[Log in to Reply]  [No Email]
TomWNC

08-26-2005 22:50:04




Report to Moderator
 Re: OT - How to find an auto electrical short? in reply to Bobg, 08-26-2005 06:42:36  
Years ago I made a little rig that works great for finding shorts. Take a 12V lamp socket and attach about four feet of wire to it with crimp on blade terminals on the end that will plug into the fuse sockets. Remove the offending fuse and plug in the light then hang it over the rear view mirror so it is easily seen. Start unplugging plugs in the circuit till the bulb goes out. As others have stated first thing to check is any new additions to circuit and unplug the bulbs in tail lamps etc. Good luck.

[Log in to Reply]  [No Email]
Hawaiirocky

08-26-2005 16:54:32




Report to Moderator
 Re: OT - How to find an auto electrical short? in reply to Bobg, 08-26-2005 06:42:36  
When it's a kid's car it is usually one of two things. Stereo or alarm installed by people that should not be allowed near a car.



[Log in to Reply]  [No Email]
txgrn

08-28-2005 00:02:44




Report to Moderator
 Re: OT - How to find an auto electrical short? in reply to Hawaiirocky, 08-26-2005 16:54:32  
Aloha Rocky

Mark



[Log in to Reply]  [No Email]
MarkB_MI

08-26-2005 15:39:21




Report to Moderator
 Re: OT - How to find an auto electrical short? in reply to Bobg, 08-26-2005 06:42:36  
Ask him to show you all the gadgets that he has installed. Almost guaranteed it's something that he changed. Also, if the exhaust has been altered, it could have got something hot enough to melt the insulation on the wiring. That's pretty common with tail lights.



[Log in to Reply]  [No Email]
doodelbug

08-26-2005 21:38:29




Report to Moderator
 Re: OT - How to find an auto electrical short? in reply to MarkB_MI, 08-26-2005 15:39:21  
a easier way is to disconnect the battery negative cable, put a test light in series with the battery and the cable you just removed. a short will cause it to light up , when the short is removed the light will go out.also you may never get the light to go out completly ( will glow very faint ) because of clocks and computers. one other thing, might have to remove the interior bulbs and under hood lamp or close doors and hood.

[Log in to Reply]  [No Email]
Heat Houser

08-26-2005 13:41:20




Report to Moderator
 Re: OT - How to find an auto electrical short? in reply to Bobg, 08-26-2005 06:42:36  
Using Ohms
Go to town and purchase a Volt/Ohm Meter (VOM) if you don't already have one. Look at the size of fuse. (Which is rated in Amps) There are two sockets that the fuse blades slide into. One will be power (12V) and the other will be the load. (lights etc.) With the meter set on Volts, find out which of the fuse sockets has 12V, (+/- 2 volts). Set the meter to Ohms and put one lead on the fuse socket that DOES NOT have volts and put the other lead on a good ground. Ohms is volts divided by amps. Take the amp rating of the fuse and divide it into 12. (I assume your car is a 12 volt system)
If your fuse is 10 amps, 12 divided by 10 is 1.2 Ohms. Remove all light bulbs from the circuit as they read very low Ohms when the filiment is cold. (this would skew your readings) Lower numbers than 1.2 are bad, higher numbers are good. Disconnect the tail light connectors etc. one by one until the Ohm reading gets above 1.2. Usually, you have a short and when you finally disconnect the component that is shorted, the meter will then read infinite Ohms or "Open". Typically the display shows OL for infinite Ohms. When the OL appears, the last item disconnected is the one that is shorted.

If you have a dead short, your meter will typically read around 0.2 Ohms or less. When you finally disconnect the short, the meter will go directly from the 0.2 reading to OL.

As a side note, 0.2 Ohms in a 12V circuit would draw 60 Amps. (Amps = Volts divided by Ohms)

A 10 Amp fuse in a circuit drawing 60 Amps...OOPS.

[Log in to Reply]  [No Email]
IA Roy

08-26-2005 10:39:14




Report to Moderator
 Re: OT - How to find an auto electrical short? in reply to Bobg, 08-26-2005 06:42:36  
I have used a large fuse or just a jumper wire to cause the smoke to start rolling out from the problem area. Do not do this and walk away from or go driving as this could get real exciting.



[Log in to Reply]  [No Email]
msb

08-26-2005 09:02:09




Report to Moderator
 Re: OT - How to find an auto electrical short? in reply to Bobg, 08-26-2005 06:42:36  
The trunk is the first place to look.Wires will often get damaged there.Had a car when I worked at a Ford dealership with a short in it.Finally had to trace where the wiring harness went.Found a screw holding the console in place had been driven through the harness when the car was built.Had a couple hours labor in it.Ford only paid me for 15 minutes.Go figure.



[Log in to Reply]  [No Email]
RusselAZ

08-26-2005 07:31:37




Report to Moderator
 Re: OT - How to find an auto electrical short? in reply to Bobg, 08-26-2005 06:42:36  
IF it has an aftermarket radio installed, pull it out and look at the non factory wiring and connections. I have found several light shorts in this location and some have been installed for a while. Just something about cramming a lot of extra wire into the sharp places behind the dash.



[Log in to Reply]  [No Email]
Bob

08-26-2005 06:57:50




Report to Moderator
 Re: OT - How to find an auto electrical short? in reply to Bobg, 08-26-2005 06:42:36  
Typically, cars have the dashlights and tail lights on the same fuse, so when the tail lights are lost, you will notice it because of the dash lights going out.

If there's any exposed wiring to the tail lights... under the car, in the trunk, etc., take a good look at that for any damage, including license plate light bulbs. Very rarely, there will be a loose part INSIDE a light bulb that will cause a short under vibration conditions.

There are tools on the market for automotive use that put a signal on the wire, and you trace along the wire with the a unit that will "beep" when you come upon the short. However, since this is an intermittant problem, that tool wouldn't even be of any help, if it won't "act up" while you're troubleshooting it.

Depending upon the type of fuse, an automotive parts store may have a circuit breaker that will replace it. Then, at least the lights will reset when the momentary "short" clears itself. While this is probably not advisable as a permanent "fix", it will save a lot of agravation and fuse replacement while you're troubleshooting the problem.

[Log in to Reply]  [No Email]
[Options]  [Printer Friendly]  [Posting Help]  [Return to Forum]   [Log in to Reply]

Hop to:


TRACTOR PARTS TRACTOR MANUALS
We sell tractor parts!  We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today. [ About Us ]

Home  |  Forums


Copyright © 1997-2023 Yesterday's Tractor Co.

All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy

TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.

Yesterday's Tractors - Antique Tractor Headquarters

Website Accessibility Policy