SI to CS Alternator hookup on Malibu

gmtofd

Dragway Regular
Jul 16, 2004
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Central Jersey
Successfully swapped the SI for the CS alt for the Monte in the family and plan on the swap for the Malibu. Also changed to larger diameter cables available from '90's Transports, Lumina APV and Olds Silhouettes.

Have a pair of these larger cables on the Malibu in preparation of the CS alternator, now here's the question, on the Monte the "BAT" lead is directly off the battery lead. but on the Malibu the BAT lead is coming from the ign switch. The larger dia leads allow for direct hook-up to the alternator like on the Monte, but can I also do the same hook-up for the Malibu, or just use the existing BAT lead from the ign switch and forgo the direct batter-alternator hook-up? Would like to hook-up both leads the BAT post, but I'm chicken of frying my CS alternator or the harness.

Thanks for any response.
 

Doober

Moderator
Jun 2, 2003
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The brown wire on the plug of the CS alternator needs a switched 12v source with a ~10-20 ohm resistance (the "battery" bulb will work for this) in between to trigger the alternator, and the stud on the back of the alternator uses the same wire as the SI alternator.

The plug looks like this, correct?
130-144-connector.jpg
 

Longroof79

MalibuRacing Junkie
May 10, 2004
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On the plug into the CS alternator, I have two wires connected. The "L" going to the GEN light (excite wire) and a heavier wire coming off of "S" on the plug connected to the "BAT" lug on the alternator.
I added a heavier gage 6-ga wire off of the BAT lug to the + lead on the battery.
I also did not connect the other red wire/ terminal from the original SI plug.
I notice however, I don't see the GEN light come on. I have used a multimeter and it indicated that it's charging @ 14+ volts at an idle.
I guess I shouldn't worry about it?
 

Doober

Moderator
Jun 2, 2003
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The light should only be on when the ignition's on and the engine isn't running. The light typically provides the resistance I mentioned.

The circuit for the alternator typically goes:
Switched 12v source -> alternator light -> excite wire
http://www.hotrodlane.cc/newhtml/smallalt.html
smallaltdrawing.jpg


That's the first I've really seen of a basic schematic, looks like if you connect to the other terminal you don't need a lamp or resistance.
 

Longroof79

MalibuRacing Junkie
May 10, 2004
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Gainesville, Fla.
Darren,
My concern is that the light doesn't come on with the key in the on position and not running.
I have noticed in your diagram that you have the "L" lead indicated not used with the light, and the "F" lead to be used with the light. From all the articles that I've read, they all specify using the "L" as the excite wire to the light, and the "F" lead not used at all.
But with either of these leads not connected, wouldn't the light still come on with the key in the on position?

Thanks for posting the diagram. I'm not using a resistor on the excite circuit...perhaps I might have to?
I'm trying to think what would cause the lamp not to come on at all.
 

Doober

Moderator
Jun 2, 2003
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I've never been 100% sure on the newer ones, I just remembered reading about the resistance or light. I have a Haynes manual that shows the light going to whichever terminal the brown wire goes to. I burned up several alternators in the course of a week due to what I thought was the electric fan I had mounted. I took it out and made sure that resistance was there and haven't had any problems since. I've seen a couple plugs like you memtion with multiple leads, I've always looked for ones that only have the brown wire and they've always worked for me with that resistance being in place.
 

Longroof79

MalibuRacing Junkie
May 10, 2004
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To back track a little. The alternator came out of a late '80's Cadillac. It only had the one (L) wire connected, plus the battery cable going to the "BAT" terminal. I actually added the plug with the two wires. I guess it wasn't really necessary.
Again, I was going with how it was mentioned in various write-ups.
Thanks for your input, man.

Happy New Year buddy! :D
 

Longroof79

MalibuRacing Junkie
May 10, 2004
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Gainesville, Fla.
Another thought. I wonder if this alternator is a self-energizing unit? Like I said, it does indicate that it charges.
 

Doober

Moderator
Jun 2, 2003
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I'm not sure if GM ever had any production alternators that charged? The alternator world is one of those dark arts that I haven't really looked into so I couldn't say with confidence either way. I believe there are some how-tos on the net showing how to convert, but I could be wrong.
 

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