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Alternator energize circuit not working

K

KTM300

New member
I recently bought an '06 Base model. The previous owner was having charging problems so he took it a mechanic. The mechanic told him that the computer wasn't putting out juice on the circuit that energizes the alternator. The mechanic said the options were to replace the computer or splice in a wire between the alternator and fuse box to energize the alternator. Of course he took the cheaper option. The mechanic ran a wire from a large yellow wire in the interior fuse box and connected it to the red wire on the alternator. He just used scotchloks to connect it. I plan to at least redo the connections and get rid of the scotchloks, but is there a better solution that doesn't involve buying a new computer?

 


Man, junk yard computers are cheap. I would ohm out the connection between the PCM to the BCM and the Alternator, I don't have an 06' diagram I'll post it, but bet something is going to be different

Jeff
 
Ok from the PCM it's the Black connector (C2), wire number 45 is the PWM signal out to the alternator, shows a gray wire. Wire 53 Red is the turn on signal. I don't have anything after that it says to charging circuit, but I'm missing that page.
 
J57ltr said:
Man, junk yard computers are cheap. I would ohm out the connection between the PCM to the BCM and the Alternator, I don't have an 06' diagram I'll post it, but bet something is going to be different

Jeff
Click to expand...

Jeff,

Thanks for the reply. I didn't realize junk yard computers were so cheap. I only looked at new ones. Looking on car-part.com I see yards selling them for $20. Will it have to be reprogrammed for my car?

How do you ohm a wire between the PCM and BCM? The leads on my meter aren't nearly long enough. Do you just use a jumper wire?

Do I have to ohm the wires or can I test them by checking for voltage on any of them?
 
They should be long enough you're going to have to get to the PCM it's inside the airbox remove the panel filter and just get the intake out of the way. Then remove the 2 8mm screws that are on top of the airbox and remove the top so you can access the PCM, it's just clipped in pop it out and the harness will come out twords the middle of the engine above the fans.

Disconnect the battery just in case

Meet your DMM to the lowest ohms scale you have (not the beeper) and touch your leads and wire (described below). This is lead resistance. Write that down.

use a small paper clip and bend it out so you can slide the point between the insulator and the wire and make contact with the pin. If your leads are too short grab a piece of wire to make up the difference, and wrap some around one lead the other end probe the wire you want to check you should have almost 0 ohms subtract the above reading and that is the net resistance of that wire. It should be around .5 ohms or so. Do the same with the other wire. That should tell you if you have a wiring error.

Jeff

edit: as far as reprogramming the computer you will have to do a security relearn. I am actually running an 04' GTP PCM in my 05'. I detailed the instructions in the 04+ section.

http://www.grandprixforums.net/threads/97901-How-to-perform-Security-relearn-on-04-when-changing-PCM
 
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