I'm in the process of going from a 3.4l to 3.8 SC (almost done). I got the engine and transmission out of a 98 gtp along with the wiring harness. The harness doesn't match up so I ordered a 2004 monte carlo ss l67 harness. All but three connectors are connected. The MAP sensor and the transmission external pnp sensor 2 connectors. I got the map figured out but there is no connectos for the trans switch. I got the pigtails off the gtp harness, I just don't know how to wire them into the transmission main connector. Has anyone done this before. I found this link on a gm fourm but it's for a bonnieville.
Wiring a external PNP switch to an internal PNP transmission - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat