i will know later this weekend if swapping the polarity works (I've been to busy to work on my truck)

twisted454

I AM wondering where you ran the wires from/to and how did you keep your gauge operational
oil pressure sender just works i connected the brown wire from c100 in the 5.3 harness to the wire going to the drivers side bulkhead

tach works after changing settings in computer to 3 (high and low) and connecting the output wire (AT C100) to the white wire in the connector inside the pass side dash

the coolant temp sensor you need a 3 wire sensor out of a 98 firebird and to rewire it to the 2 wires in the 5.3 harness and the third wire connects to the truck

volt gauge just works (I taped up my alternator control wire so the warning light is off as I prefer pcm alternator control)

there is a bunch more info on the site if you search for it but if you get stuck on a wiring/computer issue feel free to pm me i run a 2 bay garage (have access to wiring diagrams/pinouts)