1995 TBI to LS truck motor questions

[westofb]

Hello, I am new to this site and have been searching for some info to no avail (maybe I'm not sharp enough to find it!). I have a 1995 C1500 that has the trans going out, so I figured, what an appropriate time to tackle an ls swap. To make these dreams a reality, I bought an 01 Silverado rust bucket with the 4.8/ 4l60e trans (the trans is bad in it too, but talked to trans shops, same price to rebuild it as the current 1995 4l60e, so it is a wash). Anyhow, I parted out truck keeping the engine, trans, engine/ trans harness, radiator, etc to use for my swap....after selling parts and scraping the rest of the truck I am into my new drive train for $150 (of course still need to rebuild trans). The 4.8 wasn't my first choice (however, it will be a significant upgrade to the old 350 tbi setup as far as power, drivability, and fuel mileage) but once I get it up and running, I can always upgrade the motor to a 5.3 or better. I bought new engine mounts and R4 compressor brackets from Dirty Dingo. I am going to modify the ls harness via info off of LT1 Swap and send them my computer so it will work with my application.
All these steps, although time consuming, seem easy enough to accomplish with minimal expense. However, the part that is causing me concern, is grafting the ls harness into the trucks existing harness to get the gauges/ ac/ cruise/ etc to work with the new power train. I have found harness diagrams for the 95 truck, but am stumped on where to mate the new harness to the old to make everything work. I have found similar swap info on 93-94 trucks as well at 96 and newer ones, but nothing specifically for the 95. I am sure I am not the first to do this swap and was hoping someone that has would shed some light on where these "grafts" need to be made. Thanks for any info you can provide!

Edit Reply

[brianmcb]

You reuse your oil psi sender on the LS engine, which keeps your oil gauge working, and to get coolant temp on my truck I installed a 3 wire f-body coolant temp sender on the LS engine. Then just hooked trucks wire up to that. Your fuel level gauge is un affected. The white wire for the truck tach hooks onto the engine speed signal wire from the ls pcm. Easy peasy

[westofb]

You reuse your oil psi sender on the LS engine, which keeps your oil gauge working, and to get coolant temp on my truck I installed a 3 wire f-body coolant temp sender on the LS engine. Then just hooked trucks wire up to that. Your fuel level gauge is un affected. The white wire for the truck tach hooks onto the engine speed signal wire from the ls pcm. Easy peasy

One of these threads for a 93 or 94 I read that you pitch drak box splice the red and blue wire to the vss wire from the ls harness to enable the speedo and cruise. This hold true for the 95 as well? It has the drak box under the pcm. The tach feed connection mated at gauge or pcm? I assume the tach feed and SES lead from the ls wire harness are connected in the lead to the instrument panel, thus eliminating feed from the original pcm feed to the new ls feed? Is the 3rd wire coolant feed mated here as well? The ls install and getting it running seems to be easy part of the swap, the grafting of the two is harder to wrap my head around. Or are all these connections made on the leads feeding the trucks pcm, and the original pcm remain intact, just receiving feeds from new sources? I am probably thinking way too hard about this. Anyhow, thanks for the input, and keep info coming.

[westofb]

As I research this, the more I get confused (no doubt overthinking things again). Was looking at some info on fuel supply, lots of info on how to use corvette filter for returnless fuel system??? The 2001 ls motor I'm using has 3 feeds, actually one feed, one return, and one "vent" egr purge valve. My 95 has basically same set up. My plan for fuel system was to swap my complete sending unit with a 1996 model, which looks the same as mine but should supply the fuel requirements (I think) of the ls motor. Is my plan doable? Or do I need to research this a bit more? I do realize that my plan is going to require some modifications to the supply and return lines at the engine bay to go from tbi to ls.