LS1 alternator wiring
Thread Starter
TECH Regular
Joined: Feb 2002
Posts: 426
Likes: 45
From: ohio
LS1 alternator wiring Quick question on how to excite the alternator with different year components. I have a 99 or 00 engine trans, with an 01 wiring harness, and an unknown year pcm. The harness has the alternator (red) wire entering the red connector at pin 50, and does not seem to exit the PCM. I am guessing that since the pcm is not an 01 that pin 50 may not be exciting the alternator.
What should I do to get the alt working? Cut the pin 50 and run it to a dash light, like I have usually done? If done this way which pin in the alternator four pin connector should be used? I assume that the PCM does not need to see this wire to function correctly. Thanks, Chris
What should I do to get the alt working? Cut the pin 50 and run it to a dash light, like I have usually done? If done this way which pin in the alternator four pin connector should be used? I assume that the PCM does not need to see this wire to function correctly. Thanks, Chris
What should I do to get the alt working? Cut the pin 50 and run it to a dash light, like I have usually done? If done this way which pin in the alternator four pin connector should be used? I assume that the PCM does not need to see this wire to function correctly. Thanks, Chris
The small B terminal on the ABCD (plug) of the alternator goes to a non-LED dash bulb and then to an ignition source that is hot in the RUN/START position. Then I ran a heavy gauge wire from the + terminal on the battery straight to the alternator.
A friend of mine with a fox body mustang did it this way too and it worked for him also.
As far as I can tell, the PCM does NOT need to know anything about the alternator.
Here is a pic of the bulb I used, you can get this at any parts store, costs less than 2 bucks:
Hope this helps!
Joined: Sep 2004
Posts: 3,148
Likes: 12
From: Downers Grove, IL
Well heres how it goes. The red wire should go to pin 15 on C2 of the PCM. If its a 99-02 PCM that pin will be live. If its a 98 PCM than that will not work. You could hook it to the PCM and try it. Or you could use the method posted above, or you could hook it to the idiot light in the dash. At the worst the PCM may throw a code if you don`t hook the alt up, and its a 99-02 PCM.
Joined: Sep 2004
Posts: 3,148
Likes: 12
From: Downers Grove, IL
Yep, you need to make sure that the red wire going to the alt needs some type of resistance on it, whether it is supplied by the PCM and idiot light, or a 470 ohm 1/2 watt resistor.
Teching In
Joined: May 2004
Posts: 33
Likes: 0
From: Indianapolis
I've got the 12V wire coming off the battery and through an electric cutout. I see Radio Shack has the resistors. What's the best way to mount the resistor inline in the wire. Do they have holders you can mount in series? Surely there's an easier way than rigging up a little pc board.
Joined: Sep 2004
Posts: 3,148
Likes: 12
From: Downers Grove, IL
Just solder the resistor right inline with the wire and put a piece of shrink wrap over it. The best way would be to shrink wrap that area of the wire to a piece of plastic to act as a reinforcement, but you don`t have to do that.
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Teching In
Joined: May 2004
Posts: 33
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From: Indianapolis
I've looked around and have seen conflicting reports. Some believe that on factory alternators the resistance required is built in to the alternator. Any comment on that idea?
As it turns out the alternator I have now that I thought was blown is fine. I figured it was "burned out," but when I looked into it, the bolt holding the cable on had backed off.
As it turns out the alternator I have now that I thought was blown is fine. I figured it was "burned out," but when I looked into it, the bolt holding the cable on had backed off.
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Joined: Sep 2004
Posts: 3,148
Likes: 12
From: Downers Grove, IL
I haven`t heard or seen anything that leads me to believe the resistance it built into a factory alt. It IS built into the factory wiring harness though (harness itself in the 98`s and its internal to the PCM on the newer cars/trucks)
Resurrecting this thread -
I am swapping an '01 F-body LS1 into a '97 BMW Z3 that I bought with a Nissan SR20DET already swapped into it.
The Nissan alternator was similar to the LS1 alternator in that it has two wires going into it, one on the side terminal and one into a plug connection. Both of these wires were 12v.
Is this the same as the LS1 alternator? Unless I'm reading incorrectly above, I can simply solder in a 470-ohm 1/2w resistor in between the 12v source and the LS1 alternator plug.
Is this correct, or do I lack reading comprehension?
Thanks!
I am swapping an '01 F-body LS1 into a '97 BMW Z3 that I bought with a Nissan SR20DET already swapped into it.
The Nissan alternator was similar to the LS1 alternator in that it has two wires going into it, one on the side terminal and one into a plug connection. Both of these wires were 12v.
Is this the same as the LS1 alternator? Unless I'm reading incorrectly above, I can simply solder in a 470-ohm 1/2w resistor in between the 12v source and the LS1 alternator plug.
Is this correct, or do I lack reading comprehension?
Thanks!
Beating a dead horse but let me get this straight. I can take a wire from pin 15 on the RED ECM connector and run it to my ALT./ BATTERY light on my dash as long as it is a bulb and not a LED. This will then let me know if the ALT. has stop charging? Or do i need to still hook something else up?
Just had to do this on my car. Thank you guys for the information on this! Total life savers!
?? I'm working on a 1962 Impala. Ready to wire the alternator----If I run a 12v switched wire out of fuse box with correct resistor--will I see 5-6 v @ the alt. plug with key on? Resaon I ask is because I installed the resistor and am seeing 12v. Thanks--Lee
