308, reversed polarity jump starting... :(

Regarding the alternator light...... I believe you'll find a small diode somewhere on the back of the instrument panel that has been damaged (now conducts in both directions). I'm guessing that replacing it will fix the alternator light always on problem once the other stuff is sorted out.

 

Wiring differs with model. You mention 1980 308 GTS but further mention of Air Aux Valve become ambiguous as it's in the 1980 2V GTSI injected cars. Neither has diode in alternator circuit as does the later cars, i.e. 1983 QV. But carb cars have an air valve which runs from cat circuitry.

To be certain about the rest of the questions, please specify which car we're talking about.

Left fuse box fuses #3 & #7 + right #7 have +12v on fuses at all times. Other terminals get voltage from switches like ignition, headlight, turn signals and distribute it.

Gauges and electrovalves get voltage from left box fuse #2. Worth checking


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No diodes in alternator light circuit. Your car could be a maverick as alternator light fuses were added in 1983. - other damage requires a wild conjecture.

Gauges get their voltage from left box fuse #2 - measure voltage at the double green wire - fuse #2 bottom. Of course gauges also require a good ground, often use the multiple ground near the relay panel.

The fast idle and air diverter electrovalve may have voltage on them but they don't become active until the coolant tank temperature sensor presents a ground to the valve when the engine is cold. Pull the connector plug off the tank sensor.

Don't know what else to suggest except you should be using a voltage meter at the fusebox rather than reading resistance. A fuse can be good yet a bad fuseholder not pass voltage on properly. And fuse #2 draws my attention as it is suspiciously involved with many of your problems, including the alternator light connects there too.

And having a decent readable wiring diagram is mandatory...I can read mine for you but am out of info.

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http://www.FerrariDiagrams.com

 

Did you replace the alternator with a new one? If it is a used one, did you verify the diodes are good?

 

Glad to hear about fuse #2. There were just too many arrows pointing suspiciously at it.

Re the alternator light. When you turn the ignition on to start the car, battery voltage goes to the alternator's charging circuit THROUGHT the alternator warning light. Once the alternator start to work properly, the charging circuit voltage gets supplied to the charging circuit by the alternator itself. So the alternator light has a necessary function besides being a warning light.

Were I there I'd immediately check the alternator (new or not) condition by measuring the battery voltage before you start continuously until 4-5 minutes after you start. A good alternator (and battery) would present 12.6V before starting and between 13.6V and 14.4V after starting. Plus, voltage should stay above 13V at 2k rpm with the headlights on and never exceed 14.4V.

And there is some chance you connected the alternator wrong. The yellow wire with green stripe at the alternator...if you connected it to ground somehow, or if that terminal is grounded, the alternator light would act EXACTLY as you described. But the alternator would give full output and soon expire.

And there is some chance the alternator is good but the wrong type i.e. has an incorrect output monitor presenting a ground causing the same symptoms. These are the reasons I suggest doing a voltage check to make certain the alternator functions correctly.

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any photos?

 

Any writing/making on the dime-sized part?

 

Can you read what is written on the little black box? (can't see it well in the photo). You're probably right about it being a capacitor.

 

Your alternator output voltages are low but that could just be your voltmeter. True voltage of 12.2v for a fully charged battery would mean the battery is bad...it's only a few tenths but it should be 12.6v to 12.8v, not 12.2v. Can you borrow another voltmeter? AND do the same voltage test on your other cars for comparison. Since you know they work ok that will give you some assurance and experience on what a good battery/alternator does.

The small black plastic box in the photo is the radio noise suppression capacitor and not important (has no function) at this point. It should be in place once you've solved the main alternator warning light ?on/off? problem.

You said the light goes out when you disconnect it from the alternator so the wire isn't shorted somewhere on it's way to the dash. Were it pinched to ground, the warning light would work as you described.

I still think the alternator diodes or regulation circuitry is bad. Low voltage reading might be throwing me off but there isn't anything else to cause this problem. Please post your new readings (other car, other voltmeter).

Preaching the dangers of jump starting often takes an incident. Be glad you didn't do this to a modern car holding 12 computers.

 

unbelievable...
sometimes I really wonder what those guys are doing all day long...

where are we going if we alway have to check & control the - often payed for - work
by the "profs" ??

 

Dear Todd,
Yesterday, I had exactly the same problem with the same model of véhicle (ferrari 308 gtsi of 1980). Backwards of cables because not colour coded with the same consequences like you !!! :-( Do you remember what you have to change of pieces and if the problem was easy to solve ??? Many thanks for your help
Frederic

 

Dear Todd,
Yesterday, I had exactly the same problem with the same model of véhicle (ferrari 308 gtsi 2V of 1980). Backwards of cables because not colour coded with the same consequences like you (red light generator is on with key out of the key hole)!!! :-( Do you remember what you have to change of pieces and if the problem was easy to solve ??? Many thanks for your help
Frederic