Minor Problem Gone Haywire

Black Sun 5.0 · Mar 16, 2004

OK, I've had a 'minor' electrical problem since I've owned my car. Sometimes the lights will dim, the radio will flash and reset, the volt gauge will dip real low, and it seemed to happen most likely when it was wet outside, but not necessarily. Lately it seemed to have stabilized, everything was running great, but I had the car in the shop yesterday to have the O2's, ECT, and T-stat replaced (I know, easy stuff, but I don't have time to do the work myself). Now the car is going nuts. The radio is constantly resetting, the lights are flickering like mad, and the volt gauge goes all the way down, then will launch up to its normal range, then dive again. Any ideas? I have to contact the shop that worked on it to see what wiring they messed with. By the way, the car seems to be running fine, aside from all the other problems.

mike93lx · Mar 16, 2004

did it do it before you swapped the alternators? if not, i'd put the stock one back in and have your 130A checked out.

do you have a decent battery in there, or is it getting old?

Black Sun 5.0 · Mar 16, 2004

Yes, I had this issue before the alt. was swapped because I thought it might be the cause. I also replaced the battery, it's brand new. Trust me, I've been replacing s!@# left and right, and it's probably something as simple as a ground or a short, but I really have no clue.

jrichker · Mar 16, 2004

Look for bare wires coming from around the starter solenoid area. The other possiblity is that the fuse link in that area is damaged and is making intermittent contact. There is a 10 gauge yellow wire that feeds the fuse links for the lights, fuse panel and radio.

See See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)

http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif for more help

Black Sun 5.0 · Mar 16, 2004

Ah, a response from The Man. Thanks. I know we went over this one a few weeks ago, but as my new post says, it's haywire now. It's interesting that you mentioned the 10 gauge yellow wire that feeds the fuse links for the lights, fuse panel and radio. Not only are the lights and radio going nuts, but I did lose a fuse last week, which is typically a non occurrence with this car. I also didn't mention that just hitting the brakes also causes the problem to flare up. Is it a pain or expensive to replace the fusible link? I'm broke these days. Thanks again, I'll look into it.

jrichker · Mar 16, 2004

Fuse link replacment is an adventure: you get to strip the outer covering off of the wiring harness so that you can find the link. All I can tell you is that you get to follow the yellow wire down until it branches off into 3 black wires. Unfortunately, the black wires do not indicate what fuse link and circuit they feed. You have to keep peeling off the wiring harness wrapping until you find the place where the wire changes color again. It's Chilton or Haynes manual time for sure.

Black Sun 5.0 · Mar 16, 2004

One more question: Ever see O2's die within a year? Just got off the phone with my mechanic and he said that the 1 year old O2's were not working. Could they have been wrecked by the car's electrical problems? This mechanic is not the one I use for big jobs (performance items, major repairs, etc.), just oil changes and minor things. He thinks the mods I have killed the O2's. I doubt that. Any opinions?

blk92stangg · Mar 16, 2004

Hmm, ask him how you "kill" an O2 sensor, as I would love to know.

HISSIN50 · Mar 17, 2004

also off topic (kinda), but since Jrichker is reading this:
do you know if it is feasable to replace a burned fusable link with a circuit breaker or fuse? how would you know what size fuse, CB, etc to use (if it is possible)? i figure you are such a wiring whiz you might know (or know why not to do it). i wonder if it has to do with the "time it takes to burn up" - i dont know the technical term. would my idea trip too easily on start up, with a load, etc?

Black Sun 5.0 · Mar 17, 2004

Just an update on this. It appears that the issue may have been a bad ground after all. I stopped by the shop yesterday to pay my bill and they pulled it in to look at the car again. They found that the main ground next to the battery was bad, all brown and stuff. After closer inspection, it was apparent that the arcing was so bad, it burned a small hole through the wall. Everything got grinded down to clean metal, and it seems that everything is stable again. The only thing is that I was moving around some of the fusible links to check them out, so I may have jarred something to 'correct' the problem. Either way, all is well, for now.

jrichker · Mar 17, 2004

HISSIN50 said:
also off topic (kinda), but since Jrichker is reading this:
do you know if it is feasable to replace a burned fusable link with a circuit breaker or fuse? how would you know what size fuse, CB, etc to use (if it is possible)? i figure you are such a wiring whiz you might know (or know why not to do it). i wonder if it has to do with the "time it takes to burn up" - i dont know the technical term. would my idea trip too easily on start up, with a load, etc?

Aircraft type circuit breakers are designed for low voltage DC applicaions and would be an excellent choice to replace fuse links. They come as a push/pull to reset button, and range from 1.5 amps to 60 amps and higher.

See http://www.aircraftspruce.com/index.php or http://www.wicksaircraft.com/catalogDetails.php or http://www.sacskyranch.com/ for circuit breakers and other items.

There is a store local to Orlando that does electronic surplus and has all kinds of circuit breakers. That's where I get most of my wiring supplies. There may be a similar type store in your area.

Fuse links come with a current rating just like fuses. A clue as to what current they are design for is to look at the size wire they protect. Here's a table:

18 gauge wire = 5-8 amps
16 gauge wire = 10-12 amps
14 gauge wire = 15-17 amps
12 gauge wire = 20-25 amps
10 gauge wire = 30-40 amps
8 gauge wire = 50-60 amps.

Keep in mind that the wire size in the chart is for the circuit itself, not the size of the fuse link. The packages of fuse link repair material you can get at the auto parts stores also will have a current rating on them.

As a side note, I added a homebrew fuse panel near the battery when I installed the 3G alternator. It has positions for the foglights (now on a relay), an electric fan (future project) and 3 other circuits for future expansion.

jrichker · Mar 17, 2004

Black Sun 5.0 said:
One more question: Ever see O2's die within a year? Just got off the phone with my mechanic and he said that the 1 year old O2's were not working. Could they have been wrecked by the car's electrical problems? This mechanic is not the one I use for big jobs (performance items, major repairs, etc.), just oil changes and minor things. He thinks the mods I have killed the O2's. I doubt that. Any opinions?

Gasket sealers and engine additives are the prime killers of O2 sensors. Anything that you use has to be sensor safe, and should say so on the label. I killed a pair of O2 sensors once by using a non-sensor safe gasket sealer.

The other possiblity is that something damaged the O2 sensor's built-in heater. Poor grounds could do that as well. The O2 sensor ground is in the injector harness and comes out below the EGR valve. If the engine to chassis ground was bad, the O2 ground might end up carrying more current than it was designed for.

Black Sun 5.0 · Mar 17, 2004

A bad ground for the O2's was found some months back, that's probably the culprit there. Either way, new O2's, hopefully the car will grab some better mileage now.

HISSIN50 · Mar 17, 2004

jrichker said:
Aircraft type circuit breakers are designed for low voltage DC applicaions and would be an excellent choice to replace fuse links. They come as a push/pull to reset button, and range from 1.5 amps to 60 amps and higher.

See http://www.aircraftspruce.com/index.php or http://www.wicksaircraft.com/catalogDetails.php or http://www.sacskyranch.com/ for circuit breakers and other items.

There is a store local to Orlando that does electronic surplus and has all kinds of circuit breakers. That's where I get most of my wiring supplies. There may be a similar type store in your area.

Fuse links come with a current rating just like fuses. A clue as to what current they are design for is to look at the size wire they protect. Here's a table:

18 gauge wire = 5-8 amps
16 gauge wire = 10-12 amps
14 gauge wire = 15-17 amps
12 gauge wire = 20-25 amps
10 gauge wire = 30-40 amps
8 gauge wire = 50-60 amps.

Keep in mind that the wire size in the chart is for the circuit itself, not the size of the fuse link. The packages of fuse link repair material you can get at the auto parts stores also will have a current rating on them.

As a side note, I added a homebrew fuse panel near the battery when I installed the 3G alternator. It has positions for the foglights (now on a relay), an electric fan (future project) and 3 other circuits for future expansion.

Thank you so much for all the info.
i have never been a fan of fusable links, and it appears that there are alternatives. i will do some homework and try out your ideas. thanks for all the info, Jrichker.
BTW, i have also done a fuse panel in the engine compartment, as well as a deal to house all the added relays under the hood (3 for lighting, slots for fans, etc). i chose under the hood since i can actually access them and in AZ, moisture is not a real concern. i just keep an extra bosch relay in the glovebox.
again, great stuff and many thanks.

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