LS engine wiring harness
 

Is there someone that makes an LS engine harness that will plug into factory connections on a 1995-1999 chevy truck so it will work with all the factory dash, fuel pump, etc? I heard about something like this but haven't been able to find it.

Re: LS engine wiring harness
 

Hopefully someone else will chime in, as I can't say for certain on the 95-98 trucks, but... Neither the oil psi or temp signals are sent through the PCM. In other words, nothing changes in the wiring for those. Simply use the original senders from the original engine and install them into the LS engine and hook the wires back up. (EDIT - there is one temp sender that will go to the PCM, already wired in as part of the harness of course. You will just need to install your original sender as well)

For the fuel pump, the LS harness will have a wire that is a signal wire for the fuel pump relay. Some come with the relay already installed in the new harness, some just have the wire stubbed out. If the wire is just stubbed out, run that one to the trigger wire on the truck's fuel pump relay.

The one tricky part on those years might be the speedo. I don't know if they use an electric speedo or a cable. If it is electric, it shouldn't be a problem, one wire from the harness to the speedo. If they are cable, it will require the use of an adapter unit.

(ANOTHER EDIT - I found an instrument cluster from a 95 on eBay, and it is electric. So that part should be rear easy too.)