Hello all. I did a search on this with no luck so i'm here asking for help, please. 2 months ago I did a underdash wiring harness swap out from a 72 Malibu to the 72 SS with idiot lights, I also swapped out my external regulator alt. with an internal regulator alt and changed the plug and installed the jumper wire on the blue and brown wires that used to plug in to the external regulator. All worked fine, charging 14 volts with a multimeter and car would turn off as normal with the key. Tonight I finally installed the dash and turned the key on to check the warning lights, I started the car up to make sure the GEN light would turn off as normal. It stayed on with the key on or with the car running, I turned the ignition switch off when the car was running but the GEN light stayed on and the car kept running even with the key off. I went to the jumper wire that tied the brown and blue together and disconnected them and the car shut off. With the jumper wire out the car runs as normal but the GEN light won't work at all. If I remember right, the brown wire is the sensing wire for the GEN light right? All worked fine until I plugged the dash gauges in. Its almost like the car ignition is running off of the alternator?? I'm lost. I would like to have the GEN light work though and the car shut off with the key. I know, I want it all.:yes: Any help would be greatly appreciated.

You don't have a MSD box do you? If you do you need to put a diode in the alternator wire otherwise it backfeeds to the box and keeps running.

Yes I do. Which wire on the alternator would get the diode? Can I buy the diode from the auto parts store? Thanks alot.:hurray:

If you have a internal regulator it is the #1 wire (marked on the alternator case. If not then refer to the instructions http://www.msdignition.com/instructions/6530_instructions.pdf?terms=6al+installation+diode page 16 on this one. The wiring for the box is basically the same on all models. You can get a diode at Radio Shack but be aware that the arrow on the diode points the direction of the current flow if you have it backwards the alternator won't charge. A pack of diodes is like $1. They are pretty small and I don't know the rating but the MSD tech line can help. If you put the box in it came with one.

Bowtie70ss thank you so much for your help, Thant problem is fixed. However my GEN light stays on dim while idling and when reving up to around 2000 rpms then it goes out. Even at idling with the GEN light dim the Bat. wire on the alternator and the positive terminal on the battery both read 14.38 volts. I checked the voltage on the small wire on the 1 spot of the alternator and it only reads 11.58 volts while idling but the battery wire next to it reads 14.38 volts. What gives?

Is that reference voltage? I am not 100% on that though. Are you running the stock external regulator or did you update to a internal one. Maybe I could help out if I knew your exact setup. Let me know.