Car Expertise Needed

SexEPid

Platinum Member
Aug 1, 2000
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Hey everyone!
Been a while since I've posted here...anyways...

I own a 1982 Toyota Tercel(don't laugh), and it seems to have a little electrical problem. The fuse for the back lights and the interior lights likes to blow. This problem was first seen back in the fall, and my Dad somehow fixed it.(he really isn't sure HOW he fixed it, but he may have reset the relay switch or something). This worked for about 2 months, now the fuse is blowing again. (I don't drive the car now, but I need it soon). Ummm....can anyone give me possible tips for what it is? I really do not want to take it to a garage to fix an electrical problem when I can do it myself. Thank you all for your time, hope you understood what I wrote.

Thanks!

--Pid
 

bernse

Diamond Member
Aug 29, 2000
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Actually, you can try a slightly larger fuse - say 5A more - but don't go too big or you can risk bad things, like, uh, fire.

If it solves your problem, great. If not, you have either a short or possibly a bad ground. Even if you "know" what you're doing, they can be quite difficult to diagnose if it isn't something very obvious.

No easy advice if thats it. Keep spare fuses with you.
 

SexEPid

Platinum Member
Aug 1, 2000
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Blows immediately, it's a 5A fuse, I've tired 10 for sure and it blows immediately, haven't tried 15.
 

Pacfanweb

Lifer
Jan 2, 2000
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Okay, don't try any higher amp fuses, or you'll really have trouble.

When you say "back lights", what are you talking about?
 

SexEPid

Platinum Member
Aug 1, 2000
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Sorry, the lights on the back of the car...HOWEVER! The brake lights and back-up lights still work, just not the regular constant lighting....if that makes sense.
 

Pacfanweb

Lifer
Jan 2, 2000
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You mean the parking lights or running lights, I guess.

Okay, fuse blows immediately.....is that assuming the lights are on when you insert the fuse? Or just the interior lights are on, since I'd imagine you have the door open when you crawl down there to put in the fuse?
 

SexEPid

Platinum Member
Aug 1, 2000
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Yes, the running lights.

Actually, the fuse blows as soon as I turn on the light switch on the car. The fuse box is rather accessible in the car, so I can have the door closed and put the fuse in.
 
Oct 9, 1999
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my tercel had that with the brake lights..

i dont remember what was done to fix it.. but if i remember right.. it did fix itself.
 

Eli

Super Moderator | Elite Member
Oct 9, 1999
50,422
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Ugh, electrical problems are the worst.

If you have general electrical knowledge and a multimeter, you can start checking the wires....

It's impossible to say, unless there is a known certain spot that a wire shorts.

I'd just take it in to an electronics problem specialty place and shell it out, cause the chances of you finding and fixing it are slim if it's not an obvious problem at the light or the fuse box(es).
 

KokomoGST

Diamond Member
Nov 13, 2001
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There's a short to ground somewhere in the circuit... pretty simple stuff if you had a wiring diagram and a good voltmeter.

Any mechanic worth their salt should be able to find it quick and cheap for you.

EDIT: You shouldn't have to take it to a specialty place like Eli suggested, but it sad how few mechanics know basic electrical systems. If you took college physics, you can figure it out without a hitch. Reading the wiring diagram is the toughest part.

Look for any exposed wire... mebbe a fuse box has a short or a connector or contact. Check voltage drops across connections and such. It may even be the brake light itself (well the surrounding stuff) that's shorted.
 

Pacfanweb

Lifer
Jan 2, 2000
13,149
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Ah, okay, then the short is in the parking light circuit.

There is no easy, "I know exactly what it is" fix.

You have a dead short to ground somewhere in your parking light circuit. What you're going to have to do is trace the wires somehow to find where.

The easiest way to start, is at the light sockets themselves. Particularly behind them where the wires come in....I don't remember on that vehicle how the wires plug in, but if you could unplug them right at the socket, that'll help you narrow down which one it is.
Basically, unplug them all and flip the lights on to see if the fuse still blows. If it doesn't, plug them in one at a time until it blows, then you have the culprit.

If it still blows with them all unplugged, the short is obviously before the lights. Now is the time to look at the switch itself. You might even try this first.
Wiggle the switch around a bit to see if the short goes away. If it does, it's the switch, if not, it still could be the switch.
I suppose it's possible that a wire somewhere between the switch and the lights has been pinched or chafed somewhere, especially if the car has ever been wrecked, but if it comes down to tracing wires, you really need a DVOM (digital volt-ohm meter)(or a regular one will work, also).

Now I don't know your level of electrical expertise, but at this point, you're getting close to time to take it to a shop.
 

Ozoned

Diamond Member
Mar 22, 2004
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Originally posted by: KokomoGST
There's a short to ground somewhere in the circuit... pretty simple stuff if you had a wiring diagram and a good voltmeter.

Any mechanic worth their salt should be able to find it quick and cheap for you.

EDIT: You shouldn't have to take it to a specialty place like Eli suggested, but it sad how few mechanics know basic electrical systems. If you took college physics, you can figure it out without a hitch. Reading the wiring diagram is the toughest part.

Look for any exposed wire... mebbe a fuse box has a short or a connector or contact. Check voltage drops across connections and such. It may even be the brake light itself (well the surrounding stuff) that's shorted.


Probably the button on your drivers door that controld interior lights...

 

Pacfanweb

Lifer
Jan 2, 2000
13,149
57
91
That's a pretty simple little car, so you really don't need an electrical expert, just someone with a basic knowledge of how car's lighting systems work.
Too bad you're so far away or I'd say come by and I'll find the short for you. This is really a basic problem.

Now if you had a newer car with all the integrated systems and modules, THAT'S a pain.
 

Zenmervolt

Elite member
Oct 22, 2000
24,512
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Listen to Pacfanweb. More than likely the short is at one of the bulb fixtures. Follow his suggestions.

ZV
 

Eli

Super Moderator | Elite Member
Oct 9, 1999
50,422
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Originally posted by: KokomoGST
There's a short to ground somewhere in the circuit... pretty simple stuff if you had a wiring diagram and a good voltmeter.

Any mechanic worth their salt should be able to find it quick and cheap for you.

EDIT: You shouldn't have to take it to a specialty place like Eli suggested, but it sad how few mechanics know basic electrical systems. If you took college physics, you can figure it out without a hitch. Reading the wiring diagram is the toughest part.

Look for any exposed wire... mebbe a fuse box has a short or a connector or contact. Check voltage drops across connections and such. It may even be the brake light itself (well the surrounding stuff) that's shorted.
I agree, he shouldn't have to if he has some time to spare and basic electronics knowledge. We don't know that though, and it is true that electrical gremlins are some of the worst. It can be quite frustrating, especially if it is a pinched of worn-through wire somewhere "inside" the car.

But I agree, see if you can find the problem at a switch, light box or the fuse box.
 

SexEPid

Platinum Member
Aug 1, 2000
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Thank you all for your help.
Pacfanweb did give some amazing suggestions, I do have the wiring diagram for this car, and a voltmeter, so this should be an adventerous weekend of elimination!

Thanks everyone, I love this forum.
 

Evadman

Administrator Emeritus<br>Elite Member
Feb 18, 2001
30,990
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I had this exact problem on my '86 tercel wagon. one of the wires for the running lights worked out of the wire loom, and got cut by the steering shaft. The wire was shorting on the inside of one of the universals in the shaft.

I would suggest you start by looking at all the wiring you can see and look for obvious things such as melted or discolored wires. Overheated wires often have a "shiney" look to the cover. After that, check under the dash for the same thing.

If you see nothing amiss, pickup a chiltons book for your vehic @ the library. Check that fuse to see what it powers. Disconnect things one at a time until the fuse doesn't blow (such as dosconnecting the wires from the light switch and doing the connections manualy)

I have a sneaking suspission that it is the light switch. Call it a gut instinct. *shrug*