1979 2000 - Electrical Stuff

[PDSnare]

Hello All!

I have been the happy owner of a 1979 Fiat 124 Spider 2000 with 63K miles--until recently...

Several weeks ago my battery exploded right after I started the ignition. Apparently, the voltage regulator on the original Magneti Marelli wasn’t regulating—allowing the voltage to hit over 16 volts. With my new multimeter, I was able to confirm. After replacing the voltage regulator with a new Mageti Marelli the Spider would no longer start. Facts to note:

*** In the last few months, I have also replaced the ignition coil.
*** Upon replacement of the battery, Spider fired right up, but again the OLD voltage regulator was allowing too much voltage
*** Tested the voltage at idle and at 2000+ rpms and multimeter showed the nearly 17 volts
*** Replaced voltage regulator, putting it on the original alternator
*** Didn’t start with new voltage regulator... confirmed alternator getting sufficient voltage.
*** Ignition switch: New Sipea OEM replaces old one BUT STILL no instrument lights / gas guage or interior light
*** The engine turns over but confirmed via one of the plugs that there's NO spark
*** New used ignition coil is not getting power, but checks out on OHMs
*** All fuses checked out OK
*** Checked the the ignition pick-up and it checked OK with three consistent OHM readings

Again, this entire process began with a blown battery as a result of a faulty voltage regulator.

*** Replaced battery and was able to confirm that voltage regulator was faulty and importantly, I was able to start the Spider again--everything appeared to be working
*** With new battery checked with a very brief start that the voltage regulator was faulty... replaced it with Magneti Marelli... THIS IS WHEN THINGS WENT SIDEWAYS:
*** With new voltage regulator affixed to the existing alternator it wouldn't start. BUT do have power to alternator
*** Still no instrument lights, horn, interior light, clock, BUT I do have power to headlights/hi-beam, blinkers, wipers

Alas, appreciate any input.

Thanks all for any wisdom, insight and hypotheses.

Phil

(northern VA – near DC)

[18Fiatsandcounting]

There are several things that have power even when the ignition is off: the horn, the hazard flashers, the cigarette lighter, the clock, interior courtesy light, and in some cars, the engine cooling fan. Given that many of these don't seem to work, that would point to a problem with the fuses that control these, namely, Fuse 9 (8 amps) and Fuse 10 (16 amps). I'd check those fuses again.

Also, power for both Fuses 9 and 10 comes from a black wire from the output post of the alternator. Is it possible that this didn't get re-connected properly?

Power for the ignition system comes from the "input" side of Fuse 9, so I'd measure the voltage at Fuses 9 and 10. If all is well, you should see +12V. If you don't seen any voltage at Fuses 9 or 10 (ignition off), then there is an issue with getting power from that black wire at the alternator mentioned above.

-Bryan

[spider2081]

Power for the ignition system comes from the "input" side of Fuse 9, so I'd measure the voltage at Fuses 9 and 10. If all is well, you should see +12V. If you don't seen any voltage at Fuses 9 or 10 (ignition off), then there is an issue with getting power from that black wire at the alternator mentioned above.

I think this is correct. The black wire on the alternator output post connects to fuse 10 and fuse 10 is jumped to fuse 9 which connects to terminal 30/1 of the ignition switch. When the ignition switch is in the "start" or "run" positions terminal 30/1 connects to terminal 15/54 powering the + side of the coil. The - side of the coil is grounded by the ignition control module. The ignition control module's ground is momentary but long enough for the coil to build up enough voltage to create the spark needed.

[PDSnare]

Hi Folks... @spider2081, 18Fiatsandcounting, et.al., I may not be allowed back on this site after this revelation, notwithstanding that I'm an absolute novice in all things mechanical (I'll include HVAC in this as I've been dealing with some Trane issues)... that said, after switching out battery, confirming too much voltage was going to the car, replacing voltage regulator, checking resistance, replacing ignition swith, etc. I discovered, only by chance that the "three" wires that need to be attached to the alternator, were only "two" (including the ground). I had assumed that two wires were part of the connecting wire/lug attached to the alternator bolt. When I did a re-look from a buddies insistence, I discovered there was a hidden wire lug connector hidden in the rubber sleeve that covers the bolt and the two connectors.

Presto! Instrument lights were on, brake light on, interior light on. I had a good sense, she was going to fire up and did!

Appreciate the inputs, the thoughtful considerations and putting up with such a novice. I learned much though!

Grateful,

Phil

[18Fiatsandcounting]

No worries Phil, we still love you! I hesitate to mention all the bone-headed things I've done....

Glad it's working again.

-Bryan

[PDSnare]

Appreciate that Bryan--best,

Phil