1978 Fiat Spider with an internally regulated Bosch alternator (?stock?).
After driving at least forty miles from home, we pulled off the highway to switch drivers, the engine died. I could tell by the sound of the key-buzzer that there was something wrong with the battery; it was chiming too slow. The car would not start. The radio had acted weirdly for the last five miles. The battery did not have enough juice to turn the starter.
After we returned home with the dead vehicle, I put the battery on a trickle charger for three days. It started the car just fine on the fourth day.
The local starter/alternator rebuild guy says the alternator is fine. Auto Zone says the battery is fine.
What happened? More importantly… Why did it happen?
Alternator belt was tight, and electrical connections all were fine. No recent electrical work has been performed on this vehicle to change any connections anywhere.
Does the alternator “idiot†light need to function to trigger the exciter circuit for this alternator?
C-c-harging Woes
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pope
Re: C-c-harging Woes
Hey Mike,
Sorry to hear about your non-start problem. My suggestion is to double check the basics again. Take your alternator to Auto-zone and your battery somewhere else to double check at different places.
It sounds like a short in the system that is slowly draining the system. Isnt that radio new this year? My first inclination is always the radio. Of course this is a guess, considering the long trips you have taken this year and no problems.
Good Luck
Sorry to hear about your non-start problem. My suggestion is to double check the basics again. Take your alternator to Auto-zone and your battery somewhere else to double check at different places.
It sounds like a short in the system that is slowly draining the system. Isnt that radio new this year? My first inclination is always the radio. Of course this is a guess, considering the long trips you have taken this year and no problems.
Good Luck
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Danno
Re: C-c-harging Woes
Mike, I agree that s second diagnosis of battery and alternator are needed. I had two different places check my battery/alternator once. One place said battery good, alternator bad. The other place said battery bad, alternator good. Funny thing is that My Dealership was wrong, Wal-mart was right. funny how the place that would make a buck on the particular part being bad claimed it was bad (ie dealership said bad alternator, walmart said bad battery)
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So Cal Mark
Re: C-c-harging Woes
the warning light circuit has to work for the charging system to function. If the light doesn't come on with the key on, then go out with the engine running you are not re-charging the battery
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mbouse
Re: C-c-harging Woes
Thanks Mark. that was the answer i was looking for. I do not suspect the alternator or the battery. with both ends ruled out of initial suspicion, that leaves the middle.
if the alternator failed somewhere along the way, the idiot light should have come on and stayed on at some point toward the end of the forty mile journey... which it did not! i do not recall if the light came on at the start of the day...
i do recall recently tearing the dash board out to replace the speedometer. it is possible the alternator light became dislodged from its socket during that procedure.
and, POPE... wrong car. This is the white '78... which has yet to see a decent adventure all year! the OTHER spider got the radio.
if the alternator failed somewhere along the way, the idiot light should have come on and stayed on at some point toward the end of the forty mile journey... which it did not! i do not recall if the light came on at the start of the day...
i do recall recently tearing the dash board out to replace the speedometer. it is possible the alternator light became dislodged from its socket during that procedure.
and, POPE... wrong car. This is the white '78... which has yet to see a decent adventure all year! the OTHER spider got the radio.
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majicwrench
Re: C-c-harging Woes
By far the best way to test an alternator is to do it on the car. Just cause the alternator seems to work when someone, who may or may not know what they are doing, tests it on a bench, doesn't mean much. Almost certainly NOT your battery, if you were driving along and the radio was failing, the voltage was going too low, the battery has nothing to do with this.
Test battery voltage before starting car, full charged battery should be around 12.5volts. If lower,needs charged. If higher, let it sit an hour and check again, batteries have to rest to come back to their "normal" voltage.
Turn key on. Charge light should light up. If not, needs to be fixed. Start car, light should go out.
Check voltage again. At idle with everything off, battery should now read somewhere around 14v. If it still reads your beginning battery voltage (or less), charge system is not working.
Turn lights, fan on, check again at idle, may now be down around 13volts, BUT should come back up to 14v if you rev the enging to 2200rpm or so.
It is not a short, a short is something "Shorted to ground" and will result in fuse failure or burnt wiring.
Good luck!
Keith
Test battery voltage before starting car, full charged battery should be around 12.5volts. If lower,needs charged. If higher, let it sit an hour and check again, batteries have to rest to come back to their "normal" voltage.
Turn key on. Charge light should light up. If not, needs to be fixed. Start car, light should go out.
Check voltage again. At idle with everything off, battery should now read somewhere around 14v. If it still reads your beginning battery voltage (or less), charge system is not working.
Turn lights, fan on, check again at idle, may now be down around 13volts, BUT should come back up to 14v if you rev the enging to 2200rpm or so.
It is not a short, a short is something "Shorted to ground" and will result in fuse failure or burnt wiring.
Good luck!
Keith
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mbouse
Re: C-c-harging Woes
So, reinstalled the tested alternator this a.m.
Reinstalled the fully charged battery.
the idiot light does not come on when the key is turned in the ignition.
from what i have learned....this light MUST come on in order to initiate the alternator to generate any voltage.
With the alternator not functioning, it is no wonder i only went 42 miles with the lights and radio and heater fan on before the engine died.
Reinstalled the fully charged battery.
the idiot light does not come on when the key is turned in the ignition.
from what i have learned....this light MUST come on in order to initiate the alternator to generate any voltage.
With the alternator not functioning, it is no wonder i only went 42 miles with the lights and radio and heater fan on before the engine died.
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Danno
Re: C-c-harging Woes
ok. This is good info. i've been following. My light does not come on either. same problems. I checked the bulb. it's ok. where do I go from here. any ground wire that is a common culprit for this one?
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mbouse
Re: C-c-harging Woes
Danno, are you saying you've had independant tests of both the battery and the alternator... and they are both o.k.?? and the idiot light bulb will light when put in a different socket?
generally speaking, if a good light bulb is not working in its proper socket, a ground wire is to blame.
Do you have a good clean connection between the exciter wire and the alternator?
this is how the guy at the rebuild shop told me how to field test my alternator circuit:
disconnect the exciter wire from the alternator. start the car. while the car is running, jump the connection at the alternator for the exciter circuit. CAUTION, do not touch ground with the wire... hot to hot only.
test your alternator.. is it charging the system? if yes, then the problem not the alternator.
if the alternator now sends out a charge, then you need to follow back that exciter circuit all the way.
either the alternator (preferrably) or the battery must be supplying electricity to the engine to make it continue to run. if the battery is disconnected from the car while the engine is running.... and the engine continues to run, then the alternator must be providing some juice.
generally speaking, if a good light bulb is not working in its proper socket, a ground wire is to blame.
Do you have a good clean connection between the exciter wire and the alternator?
this is how the guy at the rebuild shop told me how to field test my alternator circuit:
disconnect the exciter wire from the alternator. start the car. while the car is running, jump the connection at the alternator for the exciter circuit. CAUTION, do not touch ground with the wire... hot to hot only.
test your alternator.. is it charging the system? if yes, then the problem not the alternator.
if the alternator now sends out a charge, then you need to follow back that exciter circuit all the way.
either the alternator (preferrably) or the battery must be supplying electricity to the engine to make it continue to run. if the battery is disconnected from the car while the engine is running.... and the engine continues to run, then the alternator must be providing some juice.
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So Cal Mark
Re: C-c-harging Woes
disconnecting the battery while the engine is running is not a good way to test the charging system; you stand the chance of the arc damaging some components. Especially important if you have a car with an ecm
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majicwrench
Re: C-c-harging Woes
Where to go from here....
Looking at a 78 diagram, looks like power for charge light comes from #1 fuse. So, first thing check fuse, do you have a test light or voltmeter? Don't touch fuse, test tereminals carefully in the box that the fuse touches, should be voltage on both sides of fuse with key on. If not, need to fix. Then light blu/black wire runs to chaarge light, then thru bulb,turns to black/voilet, then to alternator, where the current running thru bulb excites the alternator. So now test for voltage at black/voilet at alternator again with key on. Should be current, but may be dim with test light because it is flowing thru charge light. With volt meter will likely read tween 6 and 9volts. If you have voltage at this black/voilet wire at alternator, and light will not come on with key on enging off, remove wire from alternator and ground to known good ground. now light on dash should come on. If it does, means light circiut is good, means alternator is bad.
Hope this makes sense,
Ketih
Looking at a 78 diagram, looks like power for charge light comes from #1 fuse. So, first thing check fuse, do you have a test light or voltmeter? Don't touch fuse, test tereminals carefully in the box that the fuse touches, should be voltage on both sides of fuse with key on. If not, need to fix. Then light blu/black wire runs to chaarge light, then thru bulb,turns to black/voilet, then to alternator, where the current running thru bulb excites the alternator. So now test for voltage at black/voilet at alternator again with key on. Should be current, but may be dim with test light because it is flowing thru charge light. With volt meter will likely read tween 6 and 9volts. If you have voltage at this black/voilet wire at alternator, and light will not come on with key on enging off, remove wire from alternator and ground to known good ground. now light on dash should come on. If it does, means light circiut is good, means alternator is bad.
Hope this makes sense,
Ketih
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Danno
Re: C-c-harging Woes
perfect sense. Fuse #1, gotchya. Testing the light circuit, gotchya. Will report back in a few days when it's no longer raining.
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racydave
Re: C-c-harging Woes
I do not see where touching the fuse would be a problem. The only way you can be shocked in a car is thru the plug wires. Or always remove your rings, or watches as they can short a circut and glow red hot, again no shock but a bad burn. To keep from shorting out a circut, use a fused jumper wire to voltage.
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racydave
Re: C-c-harging Woes
In order for the charge lamp to luminate, there needs to be voltage on one side of the bulb, and a ground on the other.When the ign is on, and eng not running, the wire is grounded thru the alt. When running, the alt provides voltage and lamp will not light with voltage on both sides of the bulb and no ground. If you remove the black-violet wire from the alternator and ground it, it should luminate the bulb. If it does, the problem is at the alternator( ck terminals and wires before condeming alternator ). If not, I would check for voltage at the bulb from fuse 2 which shows as a lt blue pink wire at fuse box, changing to lt blue- black at tachometer. Ohm meters tend to lie so a volt meter or test light are usefull.This is from a 79 schematic ( thanks Brad A. ) If yours is a diff year, check the schematic. Basic principals still apply. Not sayin anyone is wrong, just another view of the system... 