I believe the wire is brown, and its PIN H on the connector off the ICM.
Back when I first bought my car, we scanned it and the tach. was way off from what it should of been. Installed an after market tach. over the factory one, and rant the feed line right off the coil pack, so what we were reading was accurate.
Got smarter years later, and realized that you could take apart the speedo cluster, pull off and reset the actual needles to make them read right. Pulled it apart, and went for a drive with the scanner. got the RPM's to a even 2K while driving and reset the needle by hand. Been fine ever since.
Not a waste buying a high dollar tach. Its been removed from my GTP for quite some time. I'm going to use it in my '95 Sonoma project, since there is no tach. in those years, and I am installing a built LT1 motor with a ATI Procharger on it, so kinda want to know what the RPM's are of this motor for sure.
Hope that helps.
~F~
