putting an ls1 in a 87 trans am and we have the harness that goes to the ecm already on the motor but how do we wire this computer in with the rest of the car and tie it all in with the fuse box.What did everyone else do besides spend lots of money on a custom harness.let me know how you guys got these ls1's wired up to your cars.any help would be great.

 

I bought an '01 Helms, used my '82 Helms, and fabricated a harness to connect the LS1 harness to the '82 chassis connectors.

'82 chassis pinouts are not same as '87 so my pinouts are not any help, but you can use the same process cheaper than buying a custom harness.

You may not even need to get the Helms, hit the Conversion and Hybrids forum on ls1tech.com and find the recent post where some guy said his local library had a subscription to some service that got him printouts of the LS1 wiring diagrams. Wish I'd known of that earlier, I dropped almost $100 on the '01 Helms books.

If you can get the diagrams and connector pinouts, you just need junkyard connectors, wire, and plenty of Metri-Pak pins from NAPA or a friendly GM dealership parts dept to do it my way. I snagged a chassis harness from a '99 V6 F-body on eBay for $40, it had everything I needed except for the new Metri-Pak pins.