89 burning up alternators

[hondaaccorddrew]

What can cause a carbed 3gee to burn up a replacement alternator in a few minutes? Previous alternator tripped battery light frequently and wouldn't power the choke heater. Still charged but battery light was always on. Replaced it and all looked good with 14.2 volts at idle. Took a ten minute trip and got a battery light. Popped the hood and it was charging at 17+ volts! And it was SMOKING! Checked grounds, the 3 spade connector plug, and measured resistance for ground and positive between alternator casing/terminal and battery with a multimeter. All under 0.3 ohms. Battery voltage under full load (fan on high, lights on, window defroster on, stereo going) with engine off is 11.75 volts. Jumps back up to 12.35 with no load, convinced battery is good. What could cause this? Before I burn another alternator up. :hmph: sorry for the long post, just giving readers as many details to work with here.

[lostforawhile]

What can cause a carbed 3gee to burn up a replacement alternator in a few minutes? Previous alternator tripped battery light frequently and wouldn't power the choke heater. Still charged but battery light was always on. Replaced it and all looked good with 14.2 volts at idle. Took a ten minute trip and got a battery light. Popped the hood and it was charging at 17+ volts! And it was SMOKING! Checked grounds, the 3 spade connector plug, and measured resistance for ground and positive between alternator casing/terminal and battery with a multimeter. All under 0.3 ohms. Battery voltage under full load (fan on high, lights on, window defroster on, stereo going) with engine off is 11.75 volts. Jumps back up to 12.35 with no load, convinced battery is good. What could cause this? Before I burn another alternator up. :hmph: sorry for the long post, just giving readers as many details to work with here.
it sounds like the heavy white wire from the battery is shorted somewhere, where are you getting the alternator? avoid autozone and advance. hang on a second and I'll post what each wire is supposed to be

[lostforawhile]

the heavy white wire goes directly to battery
white/green goes to fuse 8 in the under hood fuse box,and should be hot all the time

black/yellow should be hot with the key on, it goes to fuse 1 and the inside fuse box.

white/blue goes to the charge warning light


you need to check each wire for possible shorts, white blue changes state and is also the wire that powers the choke heater, with the engine running and the alternator charging, it should show voltage, when the alternator stops charging it shows a ground, when it shows a voltage this is also what powers the choke heater

[hondaaccorddrew]

the heavy white wire goes directly to battery
white/green goes to fuse 8 in the under hood fuse box,and should be hot all the time

black/yellow should be hot with the key on, it goes to fuse 1 and the inside fuse box.

white/blue goes to the charge warning light


you need to check each wire for possible shorts, white blue changes state and is also the wire that powers the choke heater, with the engine running and the alternator charging, it should show voltage, when the alternator stops charging it shows a ground, when it shows a voltage this is also what powers the choke heater

Does that mean I should be able to put batter voltage to blue/white and have the battery light turn off? How would you check this wire for shorts? The others go to fuses. I'm not sure there white/blue leads.

[lostforawhile]

Does that mean I should be able to put batter voltage to blue/white and have the battery light turn off? How would you check this wire for shorts? The others go to fuses. I'm not sure there white/blue leads.

the white/blue in the alternator harness, if it's not connected to anything the alternator light should go off, connect a positive voltage to it, and it should stay off and the choke should function, ground it and the charge warning light comes on, the warning light always has voltage on one side with the key on, when the warning light wire from the alternator shows voltage, this means the bulb has voltage on both sides and stays off, if it shows ground, the bulb now has voltage and ground and comes on. that wire only shows voltage with the key on and the alternator charging,if you are burning up alternators you probably have an intermittent short in the heavy white wire from the alternator, power from the alternator itself is not fused

[2drSE-i]

Another thing, if that alternator is actually putting out that kind of voltage, even for a short time, you will COOK your battery.

[hondaaccorddrew]

the white/blue in the alternator harness, if it's not connected to anything the alternator light should go off, connect a positive voltage to it, and it should stay off and the choke should function, ground it and the charge warning light comes on, the warning light always has voltage on one side with the key on, when the warning light wire from the alternator shows voltage, this means the bulb has voltage on both sides and stays off, if it shows ground, the bulb now has voltage and ground and comes on. that wire only shows voltage with the key on and the alternator charging,if you are burning up alternators you probably have an intermittent short in the heavy white wire from the alternator, power from the alternator itself is not fused

When the harness is disconnected, the light stays on. I disconnected it to stop the alternator from charging so I could drive it home without risking a fire or anything receiving deadly voltage. The black/yellow has voltage with key on and none with key off. Has no resistance to fuse 1. Green/white also passes. Always hot and has no resistance to fuse 8. Both fuses pass continuity test. What would cause the light to stay on when the plug is disconnected and the engine is on?

[lostforawhile]

When the harness is disconnected, the light stays on. I disconnected it to stop the alternator from charging so I could drive it home without risking a fire or anything receiving deadly voltage. The black/yellow has voltage with key on and none with key off. Has no resistance to fuse 1. Green/white also passes. Always hot and has no resistance to fuse 8. Both fuses pass continuity test. What would cause the light to stay on when the plug is disconnected and the engine is on?

this means that harness is shorted you need to follow it from the alternator and start looking for damage, it's also possible your choke heater is shorted, but I would have thought this would blow a fuse, you could unplug the choke heater and test it to see if it's shorted to ground, if it was shorted, as soon as the alternator started charging the positive voltage from the blue/white wire would short to ground

[hondaaccorddrew]

the white/blue in the alternator harness, if it's not connected to anything the alternator light should go off, connect a positive voltage to it, and it should stay off and the choke should function, ground it and the charge warning light comes on, the warning light always has voltage on one side with the key on, when the warning light wire from the alternator shows voltage, this means the bulb has voltage on both sides and stays off, if it shows ground, the bulb now has voltage and ground and comes on. that wire only shows voltage with the key on and the alternator charging,if you are burning up alternators you probably have an intermittent short in the heavy white wire from the alternator, power from the alternator itself is not fused

I just tested all of the wires to ground also. Is black/yellow supposed to have power to ground also? When doing continuity test with the key off it has ground. With it on it doesn't. Also, blue/white has 1.33 volts with key on. Exactly 12 voles less. Which is 12.33 on other terminals.

[hondaaccorddrew]

this means that harness is shorted you need to follow it from the alternator and start looking for damage, it's also possible your choke heater is shorted, but I would have thought this would blow a fuse, you could unplug the choke heater and test it to see if it's shorted to ground, if it was shorted, as soon as the alternator started charging the positive voltage from the blue/white wire would short to ground

I just tested the choke heater to ground and it beeps with 220 ohms resistance. Looks like its grounding out. Shit!!! I can't find replacement parts for this anywhere! Does the low oil pressure light tie into this system at all? I found it disconnected after the last oil change during the summer and reconnected it. About 3 weeks later is when this battery light kicked on.

[lostforawhile]

with the key on black/yellow should have voltage, white/green should have voltage regardless of key position ,I wouldn't worry about the odd voltage at the blue/white if it's unplugged at the alternator there shouldn't be any voltage, it's possible you are picking up the positive voltage on the other side of the bulb, the bulb would act as a resistor. You would be reading the voltage at the bulb through the bulb filament, I'm starting to suspect your choke heater coil is shorted to ground. I would start there, the blue/white wire also goes to the multi function box under the center of the dash, and to the emissions control box under the drivers seat, the voltage with the engine running acts as a status signal for those

[lostforawhile]

I just tested the choke heater to ground and it beeps with 220 ohms resistance. Looks like its grounding out. Shit!!! I can't find replacement parts for this anywhere! Does the low oil pressure light tie into this system at all? I found it disconnected after the last oil change during the summer and reconnected it. About 3 weeks later is when this battery light kicked on.
send me a pm I have one you can have, I'll have to go look in storage monday,if you unplug the choke coil does the battery light go out?

[lostforawhile]

the low oil pressure light goes from the sender directly to the lamp, then there is another circuit in the multifunction box that will cause the light to flash if it detects an intermittent drop in oil pressure, this circuit uses the status of the blue white wire to stop it from triggering when the car is off or has just been started, all that circuit does is provide an additional ground to the warning light circuit. the basic warning lamp and sender will function without it.

[hondaaccorddrew]

the low oil pressure light goes from the sender directly to the lamp, then there is another circuit in the multifunction box that will cause the light to flash if it detects an intermittent drop in oil pressure, this circuit uses the status of the blue white wire to stop it from triggering when the car is off or has just been started, all that circuit does is provide an additional ground to the warning light circuit. the basic warning lamp and sender will function without it.

Thank you so much for your help. It's the choke heater. Light is off with the choke unplugged and alternator harness unplugged where it was on with the choke plugged in earlier with the key on. Smart design for its age...

[Dr_Snooz]

I'm going to bet you have a loose or corroded wire connection somewhere. The battery isolator on my camper had a corroded terminal and it was melting wires and putting out 17V to the camper. The truck was getting only 10V. It should be very easy to find it. Just look for the connection with the melted wire (or just follow your nose). Replace the connector if you can. If you can't, then clean it up with sand paper and coat it good with a corrosion inhibitor like OxGard before reconnecting. Also, get in the habit of putting a coating of dielectric grease on every wire connector you open up on the car. It will help to prevent corrosion in the future.