I'm running a 3-wire alternator in my '87. The charging system went out on me a few days ago and I'm starting to look into it now. I'm going to check continuity on the fusible link spade wire tomorrow am. Anything obvious I should check? I don't see a voltage regulator in the wiring diagram, should there be one on this vintage truck? Also, any recommendations on replacement alternators should I have to purchase one?
CK5
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Charging circuit failure
- Thread starter rcamacho
- Start date
Well, I traced the alternator ignition hot circuit down to the primary heater/AC circuit. There is a short under the dash causing the 25A circuit to blow. I'm going to rewire the alternator activation circuit to another ignition hot circuit temporarily while I make time to take apart the dash to find the short.
fatbob
1/2 ton status
Your alt. has an internal regulator, so thats probably why you can't find it.
I'm confused on what you are refering to as the alt. activation circuit.
There are two small wires that plug into the alt numbered 1 and 2.
The #1 terminal goes to a wire that has power when the ign. switch is on. There is a resistor in that wire on trucks with a volt meter, and a small light bulb in trucks with idiot lights. If you dont have the right resistance in that circuit, the alt. will not charge intill you rev it up.
The # 2 terminal go to the battery, or to the positive cable on the starter.
When you turn on all your electrical loads and it puts a load on the battery, this SENSE wire detects the voltage level at the battery, and tells the alt to put out more. Some people just hook this wire to the output on the alt. and call it good. But the alt. will THINK the battery is fully charged and not put out as much as it could.
Heres a great link with some good info.
http://www.madelectrical.com/electrical-tech.shtml
Good luck
Bob
I'm confused on what you are refering to as the alt. activation circuit.
There are two small wires that plug into the alt numbered 1 and 2.
The #1 terminal goes to a wire that has power when the ign. switch is on. There is a resistor in that wire on trucks with a volt meter, and a small light bulb in trucks with idiot lights. If you dont have the right resistance in that circuit, the alt. will not charge intill you rev it up.
The # 2 terminal go to the battery, or to the positive cable on the starter.
When you turn on all your electrical loads and it puts a load on the battery, this SENSE wire detects the voltage level at the battery, and tells the alt to put out more. Some people just hook this wire to the output on the alt. and call it good. But the alt. will THINK the battery is fully charged and not put out as much as it could.
Heres a great link with some good info.
http://www.madelectrical.com/electrical-tech.shtml
Good luck
Bob
fatbob said:
#1 is wired to an ignition hot circuit. Unfortunately it's the 25A heat/AC circuit which has a short in the dash area somewhere and is blowing fuses. I'm fixing the short sometime this week and finding another more lightly loaded ignition hot circuit.
#2 is unfortunately wired directly to the bat terminal on the alt. which then connects to the battery junction via 8 guage or better wire. I'm planning on correcting this as well by installing a mad electrical alternator wiring kit and a real battery junction block (http://www.madelectrical.com/).
tunedportk5
1/2 ton status
I have some wiring diagrams I could snap a pic if that will help your
