Fuse box wiring

This involves the aux fuse block (underhood). I get that the "hot at all times" comes from the battery cable through the metal strip inserts. How does the "hot in run" ignition wiring work? Does a wire run from the ignition in the column to the fuse block to trip a relay or something? I just don't understand how the fuse block knows when to switch power to the terminals that are "hot in run". For example, the primary and secondary fan fuses (10 Amp)

I need to figure this out to wire a fuse block into a car that originally didn't have one.

bammax wrote:

I just don't understand how the fuse block knows when to switch power to the terminals that are "hot in run".........

This is what the eletrical gremlins were bred & trained for.
Unfortunately with thier training comes intelligence & the need to escape the fuse block & run rampant thru the electrical system.

http://ss.lencolab.com/ reference Power Distribution Circuit 3 of 4
As far as which wires and what connector in the column....Cant find that without my manual.

I keep forgeting about that site. The wiring diagram 1 shows the underhood fuse block pretty well but doesn't help much. I'll look through the site closer in a bit and see if I can figure out the answer to my problem. I have a feeling I'm over thinking things.

Power Distribution Circuit 3 of 4
shows the block circuits being energized by feed thru the ignition switch
I just dont know what connectors are what on the steering column

I'm looking at it way to fast right now. Bear with me Steve and I'll figure it out

I'm going to start sorting out the wiring ends on the fuse block I have sitting in my trunk and once I remove the ones I don't need I'll know almost exactly what I'm working with and can use the diagrams to find where it taps into the car.

Well I've been tearing into the fuse block and pulling out unneeded systems. I'm stuck on 3 fuses though.

Fuse 4 EMI
I've looked through my books and online and it looks like it's sort of a catch all fuse that runs multiple things. I don't see a need for it in my application, but am leary about removing it until I understand it better.

Fuse 5 PCM/IGN
From my reading this fuse connects the pcm to the ignition coil. I think I may need this down the road since I'm running an hei distributor and this may need to tie into that somehow.

Fuse 1 ELC
This is a 25A fuse and it looks like it's simply to run the level control and the underhood light. I thought the hood light was on the air pump circuit though which confuses me a bit.

The Body 2 big ass fuse looks to tap into the ignition switch. I'm assuming that is the way the fuse block knows when to switch power to the "run in hot" circuits. If so then I probably shouldn't have pulled it out yet

[quote="bammax"]Well I've been tearing into the fuse block and pulling out unneeded systems. I'm stuck on 3 fuses though.

Fuse 4 EMI
MAF,Secondary Air Pump relay, EGR solenoid, Evap Emission solenoid,Oxygen sensors,Auto Transmission

Fuse 5 PCM/IGN
PCM, Ignition Coil, Anti-lock module

Fuse 1 ELC
This is a 25A fuse and it looks like it's simply to run the level control
Not Used in ours (Fuse 3 is the underhood light)

The Body 2 big ass fuse looks to tap into the ignition switch. YES
Pass Key/Theft deterent/starter relay, Radio, trunk switch & latch release relay, remote locks, gigar lighter, data link connector, trunk light

Thanks a bunch Steve.

I'll drop the IGN fuse for now since the car already has that covered and I don't want to fix what isn't broken.

I'll drop the ELC fuse since it's not needed.

I'll keep the EMI and see about using it to control the lockup on the trans so that I can delete the computer control (200-4r).

The BODY 2 I'll wire back in and use it to tap into the ignition source in the dash fuse panel.

Hopefully I'll have the fuse block to the point that it controls the fans, fuel pump, and tcc for the trans and has room to expand later with both fuses and relays. As well as be a spot where I can split the battery cable off for the starter and the alternator.

You're deffinetly a life saver on this project