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gnukid
Ultra Nomad
Posts: 4411
Registered: 7-2-2006
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Car Voltage Fluctating Problem - need suggestions
Hi Motor heads, I really need your suggestions to resolve a problem.
I hit a bump and the battery flew up and crossed terminals against a metal mount. I immediately saw the voltage jack up, turned off the ignition but
the motor didn't stop! I popped the hood and the pulled the terminals and saw the problem. I imagine I was frying the system for about 1-2 minutes.
Afterwards, the voltage fluctuated from 12-18v, I changed the voltage regulator, the alternator, the battery and terminals, checked wiring and it
calmed down a bit but has progressively worsened and now I am running 15-18v all meters are pinned full. If I turn on the lights or any accessories
the voltage jacks up off the charts?
Motor 351 ford/motor is running normally
Carburated
MSD electronic ignition
new battery/terminals/alternator and regulator
Ideas please???
I can only guess a short has occured but where and how or MSD is fried but how do I know? Thanks for any suggestions.
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monoloco
Elite Nomad
Posts: 6667
Registered: 7-13-2009
Location: Pescadero BCS
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Gnu, Try some Ford forums. When I have problems with my truck I use the Powerstroke forums and get all kinds of good advice. You will find a lot of
techs willing to help you.
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arrowhead
Banned
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It would have helped if you stated the year and model of the car. If it settled down and then went up again, I'm guessing you did not get a new
alternator and regulator, but rebuilt ones. Check them again. High voltage usually means the voltage regulator is commanding the alternator to
increase its output because it senses a large current drain somewhere. A shorted diode on the alternator is your first place to look.
No soy por ni contra apatía.
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bajabass
Super Nomad
Posts: 2016
Registered: 10-4-2006
Location: La Paz,BCS
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Mood: Want to fish!!!
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If the MSD was fried the engine would not run. If you have a remote starter solenoid replace it. Check all fusable links between the battery, solenoid
and starter. Sounds like a shorted solenoid, or fusable link has has melted to a ground. Also try pulling fuses and circuit breakers as you watch the
voltmeter. If you disconnect a fuse or breaker, and the voltage drops to a normal 12.5 to 13.7, the draw is on that circuit. Good luck, I hate
electrical. That's why I own a alignment shop.
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MrBillM
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Registered: 8-20-2003
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Voltage Regulation
A proper functioning System Voltage control, whether a distinct Regulator on older models or a port on the system computer will NEVER allow a Charging
voltage above approx 14.5 volts. If, in fact, the guage readings are correct, the problem MUST be a function of THAT control circuit.
Since the specific method of voltage regulation varies widely with Make, Model and Year, a generic solution isn't possible. As mentioned, a Forum
search with specific information on the vehicle involved would be a good (and cheap) initial resource.
I've lost count of the number of customer cars that were brought to me AFTER they had replaced EVERYTHING and still had a charging problem and the
reasons were myriad.
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gnukid
Ultra Nomad
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Okay thanks guys,
The vehicle is '85 Ford Bronco with 351 windsor motor (I know this isn't a favorite).
I will accept the MSD isn't failing since the motor runs perfectly. It must be a short of some sort.
I understand from your suggestions I should try replacing the starter solenoid (though I don't understand how this relates) and check for a fused
wire, I will pull fuses and keep trying.
The wipers stopped working at this point, which is something to consider. I'll keep looking for actual failures.
The nice thing is I love hanging with my mechanics and they love weird problems, so it gives me a reason to hang out for a while and keep trying. I
really love this car, its never failed. Nice to have a a backup vehicle with my Mopar '65 slant six 225 which never fails in the brecha.
Thanks alot.
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gnukid
Ultra Nomad
Posts: 4411
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| Quote: | Originally posted by arrowhead
It would have helped if you stated the year and model of the car. If it settled down and then went up again, I'm guessing you did not get a new
alternator and regulator, but rebuilt ones. Check them again. High voltage usually means the voltage regulator is commanding the alternator to
increase its output because it senses a large current drain somewhere. A shorted diode on the alternator is your first place to look.
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I did get brand new ones and I took the old ones out and had them tested, they tested out fine but I still replaced them with new and tested products.
We have an Autozone in La Paz which has pretty much put an end to rebuilds unless you buy rebuilt, but new is so cheap. The new factory alternator is
about $38 and the regulator about $10 I have tried three new regulators so far. Thanks
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toneart
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| Quote: | Originally posted by bajabass
If the MSD was fried the engine would not run. If you have a remote starter solenoid replace it. Check all fusable links between the battery, solenoid
and starter. Sounds like a shorted solenoid, or fusable link has has melted to a ground. Also try pulling fuses and circuit breakers as you watch the
voltmeter. If you disconnect a fuse or breaker, and the voltage drops to a normal 12.5 to 13.7, the draw is on that circuit. Good luck, I hate
electrical. That's why I own a alignment shop. |
I am no electrical wizard, but this sounds feasible to me.
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landyacht318
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I know that on the pre '87 dodges, when replacing the voltage regulator, The battery must be disconnected and the case of the voltage regulator
grounded before rehooking the battery. I read how one guy kept claiming to get faulty regulators, until he read the directions, saying it must be
grounded first. When it failed the voltage was soaring like yours.
I don't know if this applies to a Ford.
Good luck, nothing like electrical gremlins to drive one to drink.
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desertcpl
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I will drink to that
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MrBillM
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Change Everything
At some point, you have to stumble across the problem.
Having worked on many vehicles where they had replaced everything they could think of, usually purchased from me before giving up and bringing the car
in, I was often confronted with the "then, I didn't need all of this stuff ". Forestalling what I KNEW was coming next, I always replied, "Yeah, I'd
be really irritated with that mechanic" which never failed to work.
It didn't matter, anyway. They just went back and charged the customer for it all.
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rzitren
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I assume you have Charging system with an external voltage regulator. The regulator has 4 terminals on it labeled I A S and F. It controls the output
of the alternator by sending power out the F terminal. The more power out the F terminal , the higher the voltage. It uses the A terminal as a
reference voltage much like a speedometer is used to determine the speed of a car. The regulator must have a good ground on the mounting screws and
also a good ground to the negative side of the battery or it could overcharge.. I would check the grounds from the battery as they may have burned
when the battery moved. Let me know.
Rick
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bajabass
Super Nomad
Posts: 2016
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Location: La Paz,BCS
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Any luck with the problem yet? Curious
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wessongroup
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| Quote: | Originally posted by rzitren
I assume you have Charging system with an external voltage regulator. The regulator has 4 terminals on it labeled I A S and F. It controls the output
of the alternator by sending power out the F terminal. The more power out the F terminal , the higher the voltage. It uses the A terminal as a
reference voltage much like a speedometer is used to determine the speed of a car. The regulator must have a good ground on the mounting screws and
also a good ground to the negative side of the battery or it could overcharge.. I would check the grounds from the battery as they may have burned
when the battery moved. Let me know.
Rick |
thanks for about the simplest explanation and a traceable route for repair for this kind of problem 
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gnukid
Ultra Nomad
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Working on this crazy problem, though it seems I need more hands, one to rev the motor and turn on/off accerssories, one to check the voltage, one to
grab at cables and one to hold the pacifico. Argh! Going for more pacifico... So odd.
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Sharksbaja
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I'm interested. Did you replace the batt after it shorted? Does it take a full charge and hold it? It may be that simple. It's possible the batt is
shorted and unable to charge thereby demanding a huge amount of current.
[Edited on 1-7-2010 by Sharksbaja]
DON\'T SQUINT! Give yer eyes a break!
Try holding down [control] key and toggle the [+ and -] keys
Viva Mulege!
Nomads\' Sunsets
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gnukid
Ultra Nomad
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No I didn't change the battery afterward, actually just before, and I failed to mount it properly which caused it to jump and cross terminals. Aha!
Hmmm Okay, let me check!
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surfer jim
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First post said you changed battery and terminals....this is one of those "trick" questions like teachers used to give for a test!
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bajabass
Super Nomad
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| Quote: | Originally posted by surfer jim
First post said you changed battery and terminals....this is one of those "trick" questions like teachers used to give for a test! |
Right you are. Disconnect battery
cables. Voltage at battery should be 12.5 - 13.5 volts with a full charge. If you shorted a cell in the battery, the regulator will tell alternator to
CHARGE! Add in additional accessory loads and the thing will charge like Hades. Just as if you had a short to ground.
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bajabass
Super Nomad
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Yeah, just like Sharksbaja said.
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