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Alternator Problem

Specter

Well-known member
Joined
Apr 20, 2008
Messages
367
Location
Karachi, Pakistan
I was reknewing the headlights and fog lights wiring as the old one had become brittle. I had to open the radiator to clean up the hacked wiring mess and use stock routing (beneath the radiator) for the wiring. The wire which comes from the B post of the terminal (+ current) and goes to the battery had some joints right after it comes from the alternator, i simply opened those joints and thats it. After cleaning the headlight wiring i re fitted every thing again. The B post joints on the alternator i opened up were re joined as they were before i opened them up. I did not want to clean them right now and thought i would do it some other time.

The headlights work great, good output from the bulbs, but i am not getting any charge from the alterntor. I read quite a lot of topics on alterntor to find out what makes it tick. What i understood was that the big black 2 wire plug on the alternator has one 12v+ swtichted wire and the other is a lamp signal for the speed meter. I checked the plug and confirmed that one wire had the ignition 12v+ GOING IN the alternator and the other wire had negative current coming OUT FROM the alternator consistenly even with the ignition key off. The second wire, the negative current is not connected to anything, i think it had a joint somewhere to some other wire but during the cleaning process i lost that joint and now its loose, i think it should not have any effect on the alternator output, is this correct?

I checked the output both on battery, and then on the B post terminal of the alternator but all i get is a lousy 11 volt current from the battery itself, there is no charge from the alternator. The alternator was working fine before i opened up the wiring. I would like to know if i screwed something up or if i missed something. I do not want to open this alternator up and then find out that the alternator is fine. There is no question of blown fuses to my understanding because im checking the output directly on the alternator.

Urgent response is highly appreciated.
Thanks!
 

broxma

Well-known member
Joined
Nov 16, 2009
Messages
911
Location
San Antonio Tx
All I got for you and don't know if you looked at this already.

click

Seems like regardless of the 2 wire connector, the alternator should charge things if it's connected to the battery. That connector is hooked up to the ignition switch but doesn't interfere with the charge line and according to the diagram, all of it returns to the positive battery terminal anyways. I'm not very familiar with the route of the two wire connector to be honest but the PDF shows it.

/brox
 

Specter

Well-known member
Joined
Apr 20, 2008
Messages
367
Location
Karachi, Pakistan
Thanks brox. I think i understood something from it.

Quoting from the pdf manual :
" When the engine is started, charging voltage is
applied to the “L” terminal of the alternator, with the
result that the charging warning light is extinguished.
In addition, because battery voltage is applied to the
“S” terminal of the alternator, this battery voltage is
monitored at the IC voltage regulator, thus switching
ON and OFF the current to the field coil and thereby
controlling the amount of generation by the
alternator.
Power is supplied to each load from the “6” terminal
of the alternator. "

I think my problem relates to the 2 wire plug. The wire i have disconnected needs to be connected to the idiot light on the speed gauge. My alternator is not applying battery voltage at wire#2 as it says above, rather giving negative which would result in idiot light switiching on if i connect it to the idiot light. I was googling this matter just mins ago and read that many alternators take a reading from the bulb to regulate the internal coil of the alternator. As soon as they get a reading they will send + current to the bulb, which will turn it off and the alternator would start charging.

I am assuming for now that this is my problem, it would be helpful if somebody could confirm or deny this.
 
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