what should i start? charging problems...

[boltthrower]

i was driving to work today and my alt gauge went from the half mark where it usually is to about 1/4 where it used to be. it would slowly drain the battery as i drove down the road with the lights on. with the lights off it would usually go back to the 1/4 mark. when i merged onto the highway the gauge slowly charged back up to the 1/2 mark but as soon as i put on the brakes and slowed down it stopped charging again. all i get is a code 47. any ideas on where to start? its friggin cold out and dont wanna spend all day outside . its for my 87 daytona shelbyz

[tryingbe]

I'd check the alternator and the battery. Auto store checks themn for free, usually.

[saw wave analog]

just got done dealing with this and it turned out that the voltage regulator in the power module had blown. hook a volt meter to the battery and see what the voltage is at idle, should be ~14.5 or so. if its lower connect a wire from the unpowered field lead on your alternator directly to ground for a second, if the charging voltage shoots up its probably the regulator, if it doesnt its the alternator, if everything looks normal it may be the battery.

external volt. regulators are 10 bucks and battery and alternator tests are free at autozone or wherever

[jdawg]

its prolly the reg in the computer

[boltthrower]

welp. i just checked the battery and it was ok. swapped alts from my 88 horizon and still same symptom. where is the voltage regulator located? is it on the lm? thanks for the replies.

[jdawg]

yea

[boltthrower]

i must be missing something because i cant find the friggin voltage regulator. is it the comp by the passenger kick panel or under the hood? a pic would help alot.

[minimopar]

There is no regulator per se. To summerize, the logic module measures the voltage and controls the power module which actually drives the alternator field coil. The code 47 means the logic module knows that the voltage is too low. This is a good sign, since it means that the wiring around the LM is correct. Since you are not getting a code 41, the LM also thinks everything is OK with the PM. Since it does charge a bit, the PM is probably fine too.

Thus, I would turn my attention to the alternator or the wiring between its field coil and the PM. Also carefully inspect the ground path between the alternator and the battery. The first big lug below the two little field coil lugs is the ground. The one on top is the positive. Either the alternator is on it's way out, or there is a problem in the wiring.

Use a voltmeter and measure the voltage across the battery. Now measure it across the positive and negative terminals on the alternator. If they are both low, the alternator or the field coil wiring is probably the culprit. If the alternator is high and the battery low, check the big wires and the battery terminals.

[jdawg]

I'm not sure but its not a part u can change u need a new comp but some guys bypass the comp and wire up an external reg, but sorry on the older dodges i cant remember if its in the kick panel or under the hood, hold on ill ask some techs

[boltthrower]

ok im reading 9 volts from the alt. what would this mean? the last alt i swapped did the exact same thing. im gonna try wiggling some wires and see what happens.... oh yea. got a code 41 and 16 now but that might be because i drove it 25 miles running on about 6 or 7 volts .

[turbovanman]

Not to be a prick but this was just covered in excrutiating detail in the last week for 2 people, do a search and your answers will be answerd.

[saw wave analog]

yea this just drove me nuts for a few weeks. im telling you, its easy as hell to test the regulator. hook your volt meter to the battery and let the car idle, you will see 11 volts or whatever crappy voltage you are getting. next take a wire and clip it to the NON POWERED field terminal on the alternator. touch that wire to a ground somewhere and watch your meter, if it shoots up then the voltage regulator part of your power module is bad. its a 10$ part in stock at any auto part store, just ask for the volt regulater for an 85 non turbo omni. takes 10 minutes to install and the rest of your pm is fine. that was my problem, and yours sounds very very similar.

[boltthrower]

well, after messing with it some more and trying another alt(i tried 3 in all) i gave up and took it to the shop..... come to find out all the alts i had were bad . well, i got a nice bill from the repair shop(not) but at least its running like a champ again.