I'm in the midst of an LT1 swap. I've read that the under hood fuse box needs to be swapped over. I have the donor car (95 Z28) in my driveway, but can't figure out how to pull that side of the harness.

I see it provides power for the fans, abs controller, cruise control, then heads through the firewall where it connects with the main fuse box and abs computer........

Do I need to open the conduit up and pull the fuse box wiring out leaving the rest behind? I tried separating the bulkhead connector, but it seems glued together and not playing nice.

I have until tomorrow afternoon before its towed away, so any help would be appreciated.

The search feature just isn't turning up answers other than it needs to be swapped. Perhaps most people just buy the motors and trannies already pulled....... wish I had!

and for giggles...... and some extra responses..... pics

http://firebirdandcamaro.net/jason/95Z28/

 

It actually has more than that in it, it also is connected to the wiring for the lights, turn signals, fog lights and actually ties into the dash harness as well. I got one out of a donor car, pulled out the stuff for the ABS and just kept the relays for the fans and injector controls (which lets you plug the C100 connector from the LT1 harness into it for injector power) which will make it easier to hook up instead of splicing the wiring in. The box I got had the bulkhead connector cut off of it and only had the underhood stuff on it.

 

Well that makes sense now that I'm looking at the diagram again

So basically chop the harness at the bulkhead connector before it goes into the car, then remove the abs and light related wires and I'm set?


You make it sound so easy! LOL

Thanks

*side note* I really appreciate all the diagrams and pictures I've found so far. This isn't as bad as I thought it would be.

My biggest challenge isn't really the wiring, its getting the ac hooked up oh, and the power steering, but that seems like having one modded or something.

alright, time to chop the harness! LOL

-jason

 

Ok, I've chopped out the lights and abs wires, but still have too many big, thick, red wires going to the now defunct bulkhead connector.... Rather not have a toasty car again

thanks

-jason

 

i have a dumb question why do u need the fuse box for a lt1 swap? i have done this and dint need it?????

 

Well to be honest, I'm not sure. I have the harness, and I've read that its easier to do the swap if you use it...... sooooooo

if nothing else, I wasted a day sorting through all the wires so it only had the injectors and fan wiring to it.

 

u can send your harness off to 350lt1 and have it moded to only have 8 wires to hook up for 250 it is well worth it

 

The underhood fusebox has the 3 fan relays, and the AC relay, plus the fuses for the ignition, and also the Fuel Injection, basically when they mod the harness, they add these relays in so you can plug the fans and ac in that if you don't have the fusebox to use to hook them up. Plus the one connector with the two pink wires for the injectors on the LT1 harness plugs directly into the fusebox and you hook up a hot in run, and a hot all the time for it to work correctly. The underhood box I got was cut at the bulkhead, so I took all the wires out for the ABS, and lights and such that I didn't need, left me with the wires with the factory connectors going to the C100 on the LT1 harness, plus the two fan plugs (since I'm using the LT1 fans and radiator as well) and that's it. Now I have the 7.5 amp fuses for the FI, the 10 amp for the ignition, and 4 relays, plus the cover for the fusebox and when I mount it, will look very clean. With that, the only wires that have to be spliced in are for the gauges and ignition which makes 5 wires, oil, temp, volts, VSS, and tach.

 

When I did my LS1 swap, I installed the ENTIRE underhood harness, to include the Bussed Electrical centers. I chose to do it that way because A) it came with the engine and B) all of my fuses and relays are now located in one neat package in the Left Front corner of my engine bay. The 4th gen harness follows the same path as the 3rd gen harness and items like windshield wiper wires, etc.. all break out where needed. I then just spliced all of my old light sockets to the 4th gen harness.
For under the dash, I used the 4th gen C200 connector and went to the junkyard to get the mating half and wired my dash to that connector. If I ever had to remove the harness for service, I can split C200 and pull it out.
The 4th gen harness plugged into 1 of 2 ignition switch connector cavities. The thirdgen dash harness plugs into the second cavity. Most circuits that ran off of the removed ignition switch connector are now powered by fuses under the hood and need to be wired accordingly. Fused Ignition and battery circuits run through the Passthrough connector at the bulkhead and are wired into C200, so for any circuits that still need power and don't have, can now be wired into C200 for proper operation.

 

Alright, so I did read things right. Having this section of the harness does make life easier. I am all about having fewer splices in the harness..... just fewer things to go wrong.

What I did was pulled all the abs, cruise and lights out of the harness. Then back tracked the harness from the bulkhead connector and pulled out the hot wires that went into the dash.

I do have like two pink wires for the injectors and an orange (i think) wire for the ignition left to hook up. Just not sure where they go, but figured they were important.

I also deleted the hot wires for the traction control and abs from the fuse box. Just one less thing that could go wrong.

Inside the car I snagged the 3 plugs and chased them as far as I could. I even managed to get the adl connector. Not a fun day by any means, but its done.

Once I repair the busted wires at the PCM, this thing might actually run...... oh wait, I need to fab up fuel lines first..... doh

thanks for the feedback

-jason

 

Do any of you guys have any pics of the fuse box wiring of what goes to what...

 

You only need the fuseblock if your car was originally carbed. Beyond that, inspect the fuseblock and hook it up. There is not this wire that wire thing for a random fuseblock

 

I do have the under hood fuse box from the donor car witch is a 95 roadmaster going in a 85 c10 truck. .