If I remove the engine's ECM wiring harness (originally an LG4 305) to clean up the engine compartment, will this make my instrumentation (speedo, tach, guages) not work, and or kill the power to the distributor and starter solenoid etc??

I want to remove it while I have the chance and yet I do not want to have to rewire the distributor and starter, and I deffinatly do not want to rendure the speedo and tach useless.

 

GM put those wires there for some reason or another. If you don't have wires connecting anything...how does anything work? Sensors and distributors aren't wireless, unless of course you've figured out a way to transmit power through air.

 

You would have to go to a non cc carb, stand alone ignition like an MSD and run wires to the sending units to keep the stock gauges. You'll also have to run the battery cable to the starter and wires to the fuse block for power distribution. Not that bad at all, but you need to know what you're doing.

 

i gutted my entire car of all it's wiring. I had to rewire the whole car, of course I have a million times less wiring than GM put in there, but I have to figure everything out myself. And, all my wires are red... thank *** for sticky white labels and sharpies!

BTW: I have my gauge cluster gutted and rewired if anyone wants a diagram on how to do it. Again, it appears i'm the only fool who wanted or needed to do it.

 

I'm the same way. My engine bay has maybe 10 wires. Gauge senders, fan, MSD , starter and alternator. That's it. I like it that way

 

Mine too, and mine's EFI I'll have to take some pictures. Only real wires visible are the injector wires (in loom and tape), the TB sensors (same in loom and tape), and spark plug wires Now to move those fuel lines to the back of the bay..

 

I need some newer pics, but now that plate is painted blac, the wires run through grommets behind the plate out of sight. I like the fuel lines on the back too

 

Sound and light are power right?

There are two wiring harnesses on my car. One goes to the ECM, and one goes into the firewall and into the driver's side of the the dash. My question was if I remove the one to the ECM, will the guages still work? Looks like I am just going to have to try it and see for myself. I will unplug the harness from the ECM, if it starts and the guages work its golden.

My car already has a 600 CFM Holley and a 70's style HEI.

 

The one that goes into the dash is what feeds the fuse block. That's where your power feed is. As long as you have that then most things should work. But if I were to go that far I would just re-wire the engine bay.

 

I may look into that.

 

it's not as hard as one would think.

btw: Does anyone know which wires coming from the column go to the blinkers? I dont want a different sw3itch, I want to use the column switch, but cant figure it out any ideas? I looked in the manual, but I must not be seeing it right...

 

Actually it is really simple.

on my 87(mpfiv6 > v8) it went like this:
1. Take entire passenger side harness out. Unhook it down in fender, unplug from inside, totally remove it and computer.
2. The drivers side is almost all used, or it was on mine. You need to trace back your alternator wires and coil power wire. All of your gauges. I tend to use mechanical oil pressure so i am running a new line anyway.
3. If you need ac or other creature comforts, trace the wires and mark them.

Its pretty easy to do, of the entire swap it was the easiest. I think it took about 3 hrs, while listening to music and indulging in cold beverage.

 

I just pulled the harness for the ecm out that is on the passenger side. Then the other took care of the gauges and other things without any rewiring. It's worked for the past years with no problems. While I was at it, I removed the ecm and pulled the bulb for the dash.

 

wow, you guys did it with grace. I took a pair of wire cutters and randomly cut here and there and well, you know.

Let us know how it goes. Be sure to rewire using relay's and a fuse box.

 

Can you give details on how you did this without any rewiring? Much appreciated.

 

That's what I did. Each time I pulled my motor out, I'd find more wires to cut/hide This last time, I moved my entire engine/ECM harness to behind my dash with the sensor wires coming out of a hole right behind the motor. My front lighting harness is run inside my driver side fender instead of along the framerail, and my fan motor harness is inside my passenger side fender instead of draping down the strut tower. Alternator was relocated to low passenger side area and wires are run long the engine by the starter. Spark plug wires are under the headers and come up to the dizzy in the back

 

you have any pics?

 

Nah, will get some soon though. My engine bay still looks dirty... lol

 

The harness for ecm plugs through the passenger side behind the front fender. You open up the door and you can see where it plugs in. I unplugged it from inside behind the kick panel and pulled it up and out. When I had it out, I then took some material to fill in the hole and seal out the weather and water. That harness has all the plug connections for your sensors but does not contain the plugs for the sending units such as water temp, oil press, etc. That is on a seperate harness that comes out of the firewall on the driverside. It's really not that hard to do at all and by not cutting it up you can always put it back or sell the harness and the ecm. Hope this helps you..

 

Yes it does. This is how I figured it would be but was not sure. Thanks.