So i am driving down the road, and i look down and my tach is at zero, yet im going like 65mph, then all of a sudden smoke comes running out from under my steering colum. I pull over instantly and turn off the car. Then nothing works, and i mean nothing, from windows to lights, NOTHING electrical works! I just got the car towed back to my house, and i havent even cracked it open as i am just frightened at what might be under my dash! Has this ever happened to anyone else? Am i going to have to replace all wiring?

 

This has happened to a friend of mine and his FC. Him and his wife were out and all of a sudden there was smoke and stuff just like you said. When we looked into it his speedometer cable was toast and his e-brake cable was starting to go. It came down that the ground strap from the engine to the body went bad and caused all the problems.

 

i hope its that easy

 

okay, this morning, i tore out the instrument panel, steering column, and checked all under dash fuses. And i didnt see one burnt wire, and no blown fuses? So i checked the funny wire style fuse panel under the hood (the one that says main head retractoror something like that). And the one that is in the middle (i think the black one, as the panel reads brown-black-brown) was burnt in half! Should i just replace this wire and try to start it up? Please help!

 

Those wires are fusible links. Replace the burnt one with another fusible link, or regular wire with a fuse in line. Do not just replace with regular wire.
After replacing the fusable link, check it out real good, for any signs of a short that caused it to blow in the first place. Even a weak ground can cause those to heat up and burn out.

 

so what sizefuse should i put in there?

 

Does it list the amp rating for the burnt fuse link on the box? If so, go slightly lower amp fuse, for testing purposes. That way, the fuse will pop before allowing any wires to get too hot and melt.
I cannot remember what the ratings are for the those fuse links, but I believe they are in 10-15A range.

 

i will get a few of both, and try the lower amp ones first, Besides a bad ground wire, what could have caused this? If that fuseable was rotten or bad, and maybe shorting out, could that have been the problem?

 

Fuse links are not supposed to wear out, but, when they get old, they can fail for no apparent reason. Generally, there is a reason behind the failure. Be it a short, or a compontent that is drawing too much power.
Smoke from under the dash generally means a short, so inspect the wiring very thoroughly. As stated by someone esle, a weak or bad ground, can cause the hand brake and speedo cables to act as a ground, and could have been the source of the smoke.

 

okay, i have inspect the wires, and the grounds, and i cant find any problems, i installed a fusable link with a 10 amp at first, then a 15 amp next with the same results. All electical works fine, then i start it up and it all seems to be okay, so i got out and checked the fuse and was blown. Then of course i shut the car off, i am kind of stumped. Could all of those fuseable links be bad? i mean they are 22 year old nasty wires. I even have the whole instument cluster out, and i cant see any damage or shorts? Where else in the car could be making the link blow? Also after the car is started, i can here a wirring or weird noise coming from where the intrument cluster should be? What the heck is going on?

 

I would just replace all the fuseble links at once, I think the brown ones are five dollars apeice and the black one is ten at the mazda delership. That fixed my problem when all my electrical went out inside the cabin.

 

If everything is working with the key on, but not in start mode, check the ignition switch and follow those wires. You may also want to check the starter wires.

 

This is a scanned page from the '79 Mazda Service Bulletin, courtesy of Ron Slabach of the SA22C.org mailing list, which has a color-to-amperage chart for fusible links:

http://intertron.com/ron/images/fusiblelinks.jpg

This is a .pdf catalog of some of Buss' fuses for the automotive market:

http://www.bussmann.com/shared/libra...o-Fuse_Cat.pdf

Page 9 of the .pdf (pg. 7 as numbered in the catalog) has fusible links listed, ranging from 20-60 amps in the style desired (FLF-xx part numbers).

All of this information is from the SA22C.org mailing list.

 

so if i read that correctly, the middle one is a 45amp fuse? That would explain why the 15's and the 20's are blowing.

 

I replaced my links with fuses. I am pretty sure that it goes 30-60-30, so the middle one is 60 as far as I remember.

 

Assuming the middle one is black, then yes.

Can you tell us where you got 30-60-30?

-dave

 

Thank you for posting this. I've looked and asked before and no one seemed to know the amperage of the fusible links. That page needs to be in the stickies. I have 5 different 1st gen FSM's and the amperage is not listed, only the wire gauge.

 

well actually i dont know if the wire is black. It is black now as it has been burnt to a crisp. If i can get some confirmation on switching the links to 30-60-30, i will do that tommorrow. Gosh i hope that works!

Trochoid, so did you have problems with your fuseable links for no reason like mine? I mean, i'll be darned, i cant find another problem anywhere with the wiring!

 

One reason I can think of for a 30-60-30 configuration surviving is that it probably sacrifices protection to the systems downstream from the fusible links in favor of protecting the links themselves--bad idea, especially given that the links are slow-blowing, providing plenty of current to completely destroy downstream components if a short or over-current condition occurs.

On the other hand, the downstream components and wiring may well be more durable than the factory fuse configuration allowed for.

Regardless, you should not be approaching this problem by merely replacing the fusible links until one doesn't burn out. You have to isolate whatever is causing this short before restoring the circuit, or you risk losing some critical systems. I see from the '84 wiring diagram--

http://www.rotaryrefs.net/rotaryrefs...7%20Wiring.pdf

--that the charging system is fed from that link. From your description of where the smoke came from--under the steering column--I'd start with the ignition switch.

Oh, and I'm uploading the fusible link chart for posterity in case the linked copy dies. Thanks again to Ron Slabach of the SA22C.org list, and the list in general. I highly recommend having the daily digest emailed to anyone who enjoys fact-based technical troubleshooting.

-dave

 

But i cant find any burnt wires in the steering column? And it is my hypothesis that the smoke actually came through the vent under column, so i beleive that the smoke source was that nasty old wire (fuseable link). Any thoughts? I have the dash in pieces, and i have looked at all wires without any damaged wires located, so.......according to the attached chart i should go 20-45-20?

 

Are you sure the smoke was from inside the car? I would check the barry. Is it strapped down? Is the negative closest to the front of the car? On the '80 I used to own, the PO didn't strap down the battery and had the batter + towards the front of the car. Well, I hit a pot hole, engine died, headlights went out, smoke started pouring out from under the hood and into the car as well. It melted the accelerator, choke, and hot start cables. Melted the fuel line and started a fire. Luckily I was able to put it out.

There are a lot of things on that main link. You can narrow things down a bit, though. If any one circuit had a short, the fuse in the car would blow before the link would. Multiple circuits could short at the same time maybe blowing the link, but maintaining the other fuses. This is not very likely, though. So it must be something between the inner fuse box and the links. Off hand, it could be:

- battery shorted to frame
- output of main link shorted to frame
- alt output wire shorted
- short in the wiring beteen the fusible links and the inner fuse pannel (WR wire) [could be in/near the ignition switch ]

Hope this helps.

Kent

 

20-45-20 is the proper configuration, according to the chart.

Kent's advice is excellent. I'd suspect the alternator, starter, or an internal short in the ignition switch, although for the switch I'd expect some visual damage to the wires and more burned fuses in the cabin fuse box. Check the areas Kent suggested.

 

Tommorrow i will swap in the proper fuses in place of the fuseable link wires. And no there are not any fuses blown under the dash, and no there are not any burnt or damaged wires in the ignition area. So i will further inspect the alternator and the starter and what not tommorrow, and let you guys know.

 

Here is what I dont understand. Every car that has had an alternator fuse was always slightly larger than the max output of the alternator. Now, since the stock alt is 50-55 amps, then why is it that you would put a 45 amp fuse on when the alt SHOULD push out more than that?

 

No I didn't have problems with mine. I was trying to find out what size of fuses to use when I replaced the links with a 2nd gen fuse block. It gave me a much cleaner look, easier service for parts and 3 more taps for accessories.