Electrical issue with friend's Festiva

[fastivaca]

The daughter of a friend of mine recently purchased a Festiva. They contacted me last week saying that there were issues with the electrics. Here's what happened as they told me:

Aftermarket stereo started sparking and smoking which, as you can imagine, startled the young lady! The car died so they had it towed to a local reputable shop. Their diagnosis was that the alternator failed in some way which caused the stereo to blow. They were also told that they needed a new headlight switch and daytime running light module. As far as I know the car was running fine before the stereo fried.

The more I thought about this the more odd it sounded. My thoughts now lean toward the stereo being the cause of the faulty alternator rather than the other way around. As for the headlight issue I'm thinking the main fuse/fusible link blew. I haven't had a chance to look at the car myself but hope do so next week sometime.

Any ideas or suggestions?

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[Damkid]

My initial thoughts, change fusible links, disconnect stereo, install charged battery and fire it up and see what happens

I wouldnt trust the alternator diagnosis, sounds too strange to me

[bravekozak]

You need an EVTM for the model year Festiva you are trying to fix. It should be easy then. More than likely, the splice job for the aftermarket stereo was a hack job. I am willing to bet there was a short and the the CIGAR and/or ROOM fuse blew.

The Red wire to the alternator comes from the HEAD fusible link.
The White wire to the alterbator comes from the MAIN fusible link.

Use the search engine to find the topics regarding replacing fusible links with long foot push in fuses. Be sure to use double quotes around the phrase "fusible links".

[Aaronbrook37]

You need an EVTM for the model year Festiva you are trying to fix. It should be easy then. More than likely, the splice job for the aftermarket stereo was a hack job. I am willing to bet there was a short and the the CIGAR and/or ROOM fuse blew.

This. Had it happen to me plenty of times when I was lazy installing radios.

[fastivaca]

Fusible links were replaced with the long leg fuses quite some time ago.

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[bravekozak]

What year Festiva are we talking about? Old Festivas did not have any headlamp relays. The HEAD fusible link would fry if there was a problem in the combo switch. HEAD power went directly to the combo switch.

In the 92 Daytime running lamps schematic, the daytime running lamp relay is energized ny the REAR WIPER fuse and power is passed from the HEAD fusible link.

Also, the Headlamp relay is between the Headlamp switch and the HEAD fusible link.

I am assuming the 10A resistor just past the daytime running lamp relay protected the instrument cluster.

I am also assuming if everything is fried, then the pink 30A long leg HEAD fuse certainly didn't protect the circuit.

I bought my 93 in Detroit. I wonder if it will pass inspection without daytime running lamps? Anyone from Canada know if that is part of the safety certification?

fast, Do daytime running lamps run only high beams? Is you high beam indicator on all the time until you turn on your headlight switch? Just curious.

[fastivaca]

DRLs use the high beams at reduced strength. I believe the DRL module drops the voltage to make that happen... could be wrong on that though. The high beam indicator is not on all the time.

As for passing inspection it depends on the regulations in your neck of the woods. Here in Alberta they are included in the inspection required for any vehicle brought in from out of province. I believe national regulations require DRLs on all passenger vehicles built after 1989.

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[Tommychu]

Don't completely discount the alt as the failure location. If the reg sees a low output voltage due to corrosion or fails closed*, it will force the output voltage up. It's not impossible to see upwards of 50 volts in an extreme case, and in a "perfect storm" situation it will just keep climbing until it melts its own windings down. An aftermarket stereo will likely have its own onboard circuit protection (most have fuses on the back, as well as internal measures) as well as being the most sensitive component (our ECU is built like a tank) so it would fail first in an over-volt situation. Headlight circuit wouldn't be that much further down the line either.
I've had 2 vehicles with this problem, and both shared the Mitsu alt with the Festiva. Just remember that the voltage sense often comes from outside the alt- one of those vehicles put the alternator in an overdrive situation because of a bad ignition switch, as I found out after changing the alt 3 times.
*not common, and often misdiagnosed because when it fails closed the resulting overvolt fries it until it opens the circuit again.

[Tommychu]

Also if the alt was overvolting, that battery probably toast and in a state where it's at a high explosion risk right now, so be careful and look for signs of gassing/acid discharge. And don't hook booster cables up to it until you're sure it's good.