ordonez1307

Hey guys,
I have a suspicion that my alternator is currently not charging the battery.

A bit of background on my build. Build Thread:https://www.v8miata.net/general-moto...ls-build-2480/

My Miata alternator circuit looks like this:



The 3 wires on the Miata harness are:
White: This is bolted to the post on the LS alternator
White/Black (goes to the dash): This is disconnected and taped up in the harness.
White/Green (goes to the fuse box): This is disconnected and taped up in the harness.

The BP Automotive LS Swap harness I have hooked up in the car has a gray wire and a brown wire in the connector that are hooked to the alternator.

My question is, do I need to tap one of the White/Black or White/Green wires into the BP Automotive harness to have the alternator charge the battery?

wcw5023

From what I understand of the LS alternators, the PCM needs to signal the alt to charge, so I believe there should be a signal wire going to the alt which you seem to be missing. This would not be aparent when just looking at miata diagrams. The white/blk line should need to be spliced into the red wire on the LS harness

.boB

This worked for me.



Scroll down the page a little bit

Main Harnesses ? Racing the Exocet

BGordon

I seem to have the same problem of the single wire LS1 harness not telling the Cadillac CTS-V alternator to charge.
I bought a Painless Wiring connector that has two wires on the 4 pin connector.

It comes with a connector and 5 ohm resistor.
Hooked it up according to the instructions that came with it but no charging is going on.
According to the diagram in the above post, the harness single wire needs to be split with one going directly to the I (pink on my connector) and the second going thru a resistor and being connected to the L (brown on my connector) which seems to match the Painless Wiring instructions.

My question is this,
Any other instructions as to how to get the LS1 ECU to work nice with the CTS-V alternator?

Edit: I called the Painless wiring tech support line this morning and was told to ignore the LS1 alternator wire that comes from the ECU and connect to a switched source, preferably 16 ga. wire. Will try to come up with a wire under the hood this evening.

Edit #2: this did not work either.

Thanks.

BGordon

Well, I did something that perhaps should have been done when I first figured out there was a problem.
Originally I bought the GM Performance accessory drive system thru Summit Racing.

I called their tech support line and after giving them my name so they could check to see exactly what I purchased I explained the problem. The tech let me get about half way thru my explanation and then said "Absolutely the CTS-V alternator is a newer generation alternator and will not work with the 2000 model LS1 computer module. The LS1 uses a 1 wire style and the CTS-V uses a 2 wire style even though both utilize the same style of 4 wire connector."
At that point I asked what is the fix and he sais the only fix he knows is to utilize an earlier LS1 Alternator that bolts into the CTS-V brackets.
The correct alternator is SUM-810347.

Amazing bottom line.
They are swapping out the correct alternator for the one that came in the kit and paying shipping both ways and refunding me $45 to cover the difference in price of the two items.

It will take a couple of days to get the new alternator but presuming it all works out I will be a happy person as this is the only hiccup I have run into when using the CTS-V accessory drive with the LS1 engine.

Edit; The LS1 alternator listed above does NOT bolt up correctly with the CTS-V serpentine belt system because the pulley does not line up with the rest of the pieces.
What I ended up doing to fix that problem is to go to Amazon and purchase a bracket that moves the alternator back a bit and supposedly makes it line up with the rest of the stuff. Off the top of my head it was about $50 and was listed as working for 2007 Corvette pieces with earlier style alternators. My presumption was that it should work as I am using a 2007 Corvette harmonic balancer.
Once I got it and bolted up the stuff it still did not line up correctly but I was able to fix the problem by trimming the spacers to make them just a bit shorter. Not sure if there might be some specific alternator that would work but the 2000 LS1 alternator ended up being what I made work.