Alternator Short?
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Freshman User
Joined: Jan 2005
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From: Brentwood, TN
Alternator Short?
I did a frame off on my 1950 F1 but that was years ago and health issues have precluded me from playing with it for several years.
So, my batteries keep dying, even when I drive it and have a battery tender on it. So I used a multimeter, one side to the negative post on the battery, the other to the disconnected ground cable. At 10amp the needle jumps all the way across telling me I've got a major short.
Only one thing ended the short. Disconnecting the two top wires (plug connection) from my Delco alternator. I didn't hook up this alternator, a mechanic friend of mine did. The 10 gauge wire goes from the nut connection on the alternator to the left side of the solenoid on the same post as the + battery cable. On the upper plug connection, one wire goes to one of the posts on the front of the solenoid, the other is just a short jumper back to the nut connection on the alternator.
What am I doing wrong? Thanks guys.
So, my batteries keep dying, even when I drive it and have a battery tender on it. So I used a multimeter, one side to the negative post on the battery, the other to the disconnected ground cable. At 10amp the needle jumps all the way across telling me I've got a major short.
Only one thing ended the short. Disconnecting the two top wires (plug connection) from my Delco alternator. I didn't hook up this alternator, a mechanic friend of mine did. The 10 gauge wire goes from the nut connection on the alternator to the left side of the solenoid on the same post as the + battery cable. On the upper plug connection, one wire goes to one of the posts on the front of the solenoid, the other is just a short jumper back to the nut connection on the alternator.
What am I doing wrong? Thanks guys.
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Freshman User
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From: Brentwood, TN
PS: With all three wires hooked up to the alternator my gauge says I'm getting about 14 volts. If I disconnect the two wire plug connector off of the alternator, making it a one-wire set-up, it says I'm getting 12 volts.
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Disconnect the wire that's connected to the post on the front of the solenoid and tell us if it gets better. One of the two small wires is the voltage sense and should go to a battery connection. The other one is for an "idiot light" and will cause current draw if tied to battery and engine is not running. The question is: which one? Let us know which one causes the drain and we'll help you straighten it out.
Glad that you're feeling up to messin' with the Ford!
Glad that you're feeling up to messin' with the Ford!
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Freshman User
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From: Brentwood, TN
Wow. That is drastically different than my current wiring.
What I don't get is the 'switched' wire. Where does this connect to?
Is this connected to one of the front posts on the solenoid?
Thanks for you help with this!
What I don't get is the 'switched' wire. Where does this connect to?
Is this connected to one of the front posts on the solenoid?
Thanks for you help with this!
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Freshman User
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From: Brentwood, TN
Horvaths:
I disconnected the wire going to the front of the solenoid and still had the apparent short as long as the top plug wires where inserted in the alternator. Pull out the top wires and no short.
Also noted the stereo is drawing power. I'll change this where it won't.
I disconnected the wire going to the front of the solenoid and still had the apparent short as long as the top plug wires where inserted in the alternator. Pull out the top wires and no short.
Also noted the stereo is drawing power. I'll change this where it won't.
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Don't forget dome lights while testing for current draw. More to follow, work beckons.
Similar to drawing above, red wire at pin 2 goes to battery circuit to sense voltage. However, I just don't connect wire at pin 1 (typo, corrected). If a wire is on the pigtail it should be either insulated or connected to an indicator light. The other end of indicator light would then go to ignition circuit. This makes the light illuminate whenever ignition is hot but the alternator has no field (for example, key on but engine not running, broken belt, or bad alternator).
Similar to drawing above, red wire at pin 2 goes to battery circuit to sense voltage. However, I just don't connect wire at pin 1 (typo, corrected). If a wire is on the pigtail it should be either insulated or connected to an indicator light. The other end of indicator light would then go to ignition circuit. This makes the light illuminate whenever ignition is hot but the alternator has no field (for example, key on but engine not running, broken belt, or bad alternator).
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Verify the pin numbers at the connector. They are usually cast into the alternator body. Then double-check wiring.
If the "idiot light" winding was connected directly to the battery, with no light to minimize current, then the field winding may have fried. I'd take it to a reputable shop or parts store for testing.
If the "idiot light" winding was connected directly to the battery, with no light to minimize current, then the field winding may have fried. I'd take it to a reputable shop or parts store for testing.
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Freshman User
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From: Brentwood, TN
F-1
I wired the red wire to the big + terminal on the alternator and hooked the white wire (#1) to the post on the front of the solenoid. The solenoid post only has power when the ignition switch is on so I guess it is switched already. Did not ground the alternator as it should be grounded already or it wouldn't be working.
And I still have the short issue (multi-meter pegging when connected to the negative battery post and the disconnected ground cable).
Could this be a short inside the alternator and if so, how could I check it? I really don't want to replace the alternator for the fun of it.
Thanks.
I wired the red wire to the big + terminal on the alternator and hooked the white wire (#1) to the post on the front of the solenoid. The solenoid post only has power when the ignition switch is on so I guess it is switched already. Did not ground the alternator as it should be grounded already or it wouldn't be working.
And I still have the short issue (multi-meter pegging when connected to the negative battery post and the disconnected ground cable).
Could this be a short inside the alternator and if so, how could I check it? I really don't want to replace the alternator for the fun of it.
Thanks.
Fleet Owner
Joined: Jul 2004
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From: NM
The small post on the solenoid? It only has power when you're cranking to start. If it is a '52 truck, anyway. Edit: I see you have an earlier truck. The small post on your solenoid (if it is original) is hot ALL the time. If you ground it, your engine will be cranking. Do not connect there.
Bad assumption on grounding; are you using the slingshot style alternator mount? They are coated with thick paint, an 8 ga. ground wire to the battery Neg. terminal is a good idea.
The white wire to #1 needs to come from the IGN terminal on the ignition switch. If you want a light, here's how
Bad assumption on grounding; are you using the slingshot style alternator mount? They are coated with thick paint, an 8 ga. ground wire to the battery Neg. terminal is a good idea.
The white wire to #1 needs to come from the IGN terminal on the ignition switch. If you want a light, here's how
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Freshman User
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From: Brentwood, TN
I don't have a light, instead I have a volt gauge in the dash. The gauge would go where you have the light in the diagram?
Thanks for being so patient with me guys.
It's good to be back playing with my F-1.
Just amazing how much crap I've forgotten about!
Thanks for being so patient with me guys.
It's good to be back playing with my F-1.
Just amazing how much crap I've forgotten about!