Wiring..

[468Blazer]

The way I did it was take all connections from engine and engine bay that connected to harness and pulled it over the drivers fender to be out of the way. In the harness you will have some connections like underhood light, etc that most likely you will want to keep.

[aarolar]

Yeah that's what I finally did. the wire running through the firewall on the passanger side we disconnected under the dash on the inside I don't know if that was the right place or not but we have the motor floating in the engine bay now and are going back with friends after lunch to pull it out.

[NITROUS]

You shouldn't need the old pcm unless you run in to fuel pump sending unit issues like some of the 98's and newer trucks have since they read different. I would pull the following:

1. Torx bit screw out of the C100 connector and pull connector off.
2. Pull out the 3 bolts under the fender well that hold the fuse box in place.
3. Disconnect the plugs by the A/C blower under the dash and pull the harness through the firewall under the A/C accumulator once you pull the 2 screws out.
4. Remove the battery cable to the fuse box under the hood.
5. Disconnect wiring harness on the firewall under the wiper box and cruise control module.
6. Disconnect the ground straps and pull harness with the engine.

Once this is done you can lay everything out neat and remove everything you don't need and also compare to your new harness.

This just made the swap easier and not quite so cluttered but do it the way you feel is easiest.

[aarolar]

You shouldn't need the old pcm unless you run in to fuel pump sending unit issues like some of the 98's and newer trucks have since they read different. I would pull the following:

1. Torx bit screw out of the C100 connector and pull connector off.
2. Pull out the 3 bolts under thfender well that hold the fuse box in place.
3. Disconnect the plugs by the A/C blower under the dash and pull the harness through the firewall under the A/C accumulator once you pull the 2 screws out.
4. Remove the battery cable to the fuse box under the hood.
5. Disconnect wiring harness on the firewall under the wiper box and cruise control module.
6. Disconnect the ground straps and pull harness with the engine.

Once this is done you can lay everything out neat and remove everything you don't need and also compare to your new harness.

This just made the swap easier and not quite so cluttered but do it the way you feel is easiest.

Why couldn't you have told me this earlier. I pulled the motor and left the harness in the truck and it was a pain in the ass. I will go in tomorrow morning and get that cluttered harness out of there though.

Just an update we got the motor in and fabbed up the engine mounts and got the attached to the frame and all we have to do tomorrow is drop in the the motor and bolt it up. I decided not to notch my frame so I will be going the expensive route with that.

One question, where is this elusive C100 connector?

[NITROUS]

C100 is behind the fuse box on the firewall. It's the larger connector towards the bottom. Sorry for the late reply on this, I didn't snap you were doing right away.

[aarolar]

C100 is behind the fuse box on the firewall. It's the larger connector towards the bottom. Sorry for the late reply on this, I didn't snap you were doing right away.

Just screwing with ya it's all good, I can pull it out just as easy now as before. It's kinda confusing cause I am getting contradicting information on the harness deal. Some say leave it in and some say take it all out.

Boat Anchor out.


Empty engine bay, note birds nest of wires on the fender.

[NITROUS]

You can do it either way. It's a hell of alot eiser to pull out the iring you don't need and wrap it back up with the harness out though. The worst of it all is dropping the lower control arms to get to the motor mount bolting. I didn't have access to all of mine but it sure made installing the engine easier because I was able to align everything loose and then tighten things up centered.

[NITROUS]

While you have everything out go ahead and stck a transmission oil cooler in and make your brackets for electric fans. The LS1 fans work great!

[aarolar]

What about ABS I noticed when I pulled out the old harness some of the plugs on it went to the ABS module. I was under the impression it was a standalone system... Will I be able to retain it easily or what?

[LS1GMCTruck]

You can do it either way. It's a hell of alot eiser to pull out the iring you don't need and wrap it back up with the harness out though. The worst of it all is dropping the lower control arms to get to the motor mount bolting. I didn't have access to all of mine but it sure made installing the engine easier because I was able to align everything loose and then tighten things up centered.

I didn't even do that. I fabricated simple adapters to bolt from the exsisting V-6 frame mounts, to the standard LS1 block mounts. Worked perfect. Nice & low...and engines right up against the firewall like I wanted. With the Vette accessories I used, I have gobs of room between the front of the engine & the radiator & the best center of gravity(CG) possible.