my center fusable link blew out for the first time. I had replaced the fusable links with fuses so i could see when they blow. I had a 30 amp in there and now i put a 40 in there. What could be causing this? Thanks.

when does it blow??????

It was funny it blew after i turned my car off i guess. It was fine when i was driving it..i turned it off and went back to it an hour later and it was blown.

Maybe i should also add that it blew after i shut it off from its 20 minutes of running to jump start my other car.

I believe fusible links have a higher current rating than 30 or 40 amps. Check what the center link feeds and see where it goes. It's even possible you have a short down stream. Hard to find if you don't look at a wiring diagram and see what it feeds.

it goes to the alt. before the ignition switch. sounds like you could have done some thing to your alt. while jumping other car..... Bret

yea everything seems fine now. The alternator is an XT6 alt so its a strong one. Ill just cross my fingers and see how it goes. Im running two 30 amp fuses and one 40 amp. Do you think i should go higher Ed?

I would check all the wiring for the alt. if you go with higher fuses that will allow things to catch on fire instead of blowing the fuse..... It could be a wire rubbed thin, intermitently grounding from movement. My fusible link box is on the passenger side and says green, red, red starting from the windsheild towards the front of the car...... Bret

Yea u have the same links that i used to have. I replaced them all with fuses now and i didnt know what subarus color coding meant. I just threw in some fuses that i had hanging around to see what happened. And thanks for the tip. I will check the wire coming off the alt again and make sure its not rubbed thin somewhere.

yea everything seems fine now. The alternator is an XT6 alt so its a strong one. Ill just cross my fingers and see how it goes. Im running two 30 amp fuses and one 40 amp. Do you think i should go higher Ed?

I'm not sure of the current rating since the '83 FSM doesn't have a current value for the links.

 

However, it does say that the cross section of the green fusible link is .5 square mm and the red link is .85 square mm. If someone has an electrical manual and can see what the current carrying capacity is for copper wire of that diameter.

 

However, that's not the point. The comment for the red link direct from the service manual is "Fusible link should melt within 15 seconds at a current flow of 130 amperes." Green link "should melt within 15 seconds at a current flow of 80 amperes." So you see that fusible links are not fuses but safety devices. Fuses will blow pretty quickly at those currents.

 

Using an old fusible link might cause it to burn out since it's no longer able to handle the rated current draw for a long enough time. Scour the wrecking yards and pull a selection of fusible links for yourself until you find what's causing the failure.

 

As a help, the center link feeds the contacts of the lighting relay; after the lighting relay contacts the wiring is split between the three fuses for the headlights and tail-lights (two 10A and one 15A). Since these fuses aren't blowing the wiring problem (short) should be before the fuseblock.

 

In addition the center link feeds a 10A fuse going to the horn and hazard switch. Same comment applies; i.e. the short you're looking for has to be before the fuse.

 

If someone in the Bothell, WA area has a scanner, they could scan my FSM and post the info for you.

it goes to the alt. before the ignition switch. sounds like you could have done some thing to your alt. while jumping other car..... Bret

FL1 (i.e. center fusible link) does not go to the ignition switch or alternator. FSM shows it goes to the headlamp relay and horn/hazard switch fuse.

However, that's not the point. The comment for the red link direct from the service manual is "Fusible link should melt within 15 seconds at a current flow of 130 amperes." Green link "should melt within 15 seconds at a current flow of 80 amperes." So you see that fusible links are not fuses but safety devices. Fuses will blow pretty quickly at those currents.

wow. For the last six years, and ESPECIALLY for the last 2 1/2, I have been despising fusible links, and not understanding why they didn't not just use a fuse in these circuits instead. I have been explaining how the fusible links on my datsun caught fire, and then always having to explain that a fusible link is a fuse basically..

 

..AND in all that time, no one has ever explained a fusible link to me like this. Thank you, now it makes sense and is obvious.. but what might the potential problems be from replacing a fusible link with a fuse of the same amperage rating? In other words, what might be a "con" to the idea of retrofitting fuses or circuit breakers into place instead of fusible links?

My bad.... I took a quick look at schematics for FL2 (what I thought would be the middle fuseable link). I'll be more carefull....... Bret

My bad.... I took a quick look at schematics for FL2 (what I thought would be the middle fuseable link). I'll be more carefull....... Bret

It is confusing; I had to look in two different places to be sure I had it right.

wow. For the last six years, and ESPECIALLY for the last 2 1/2, I have been despising fusible links, and not understanding why they didn't not just use a fuse in these circuits instead. I have been explaining how the fusible links on my datsun caught fire, and then always having to explain that a fusible link is a fuse basically..

 

..AND in all that time, no one has ever explained a fusible link to me like this. Thank you, now it makes sense and is obvious.. but what might the potential problems be from replacing a fusible link with a fuse of the same amperage rating? In other words, what might be a "con" to the idea of retrofitting fuses or circuit breakers into place instead of fusible links?

I think the reason for a fusible link instead of a fuse of the same current rating is cost. A hunk of wire with two connectors on it is much cheaper to manufacture than a fuse of a certain rating and 15 second delay. Especially since fusible links aren't supposed to "blow." They are purely a safety item.

Perhaps this should be posted in off topic, but I think it's a funny story related to this. My wife's former daily driver was a '93 Geo Metro (I know; but I finally got her into an Impreza:) ).

 

Anyway, this Geo would periodically blow the 40 amp fuse that acts as one of the fusible links in the car. First time it happened, she called me to tell me the car had a dead battery and wouldn't start.

 

I jump started the car and she drove out of the parking lot and 50 feet down the road it came to a stop again.

 

To make a long story shorter, I found the 40 amp "fuse" and replaced it. but every once in a while it would blow again.

 

The point of this tale is that the link fed the charging current from the alternator to the battery and when it blew, the alternator wouldn't charge the battery. And to make matters worse, the charge light was on the same circuit and never came on! The only tip off was the lights would start to go dim or the wipers would slow to a crawl in the rain. And when the battery got low enough the ECU shut down the engine.

 

We carried extra 40A links in the glove box for about three years when the switch assembly on the steering column went bad. After replacing that, the 40A link never went again! I never did find the short but it was certainly in the switch assembly somewhere.

FL1 (i.e. center fusible link) does not go to the ignition switch or alternator. FSM shows it goes to the headlamp relay and horn/hazard switch fuse.

 

Are you sure that thats all that fusable link does. Because when it is blown my car will crank but the tach wont move and it wont start...kinda like the coil is dead.

My 84 book shows that fuse 13 (15amp) is for the ignition coil. If it turns over the fusible link is not blown... but the fuse for the ignition coil could be... This is from an 84 subaru service manual.... yours is similar..... check your fuse box... each fusable link is associated with certain fuses in the fuse box..... Bret

Are you sure that thats all that fusable link does. Because when it is blown my car will crank but the tach wont move and it wont start...kinda like the coil is dead.

I'll look over the prints again tonight. Sometimes the automatics are wired differently from the manual transmission models. Which GL do you have? Wagon or Hatch?

his is a 2wd sedan.

thanks 86bratman. I havent been on here much recently so i let this thread fall to the bottom. Yes mine is a 2wd sedan. It started life as an automatic only to be swaped to 5 speed by me