1984 Jeep CJ7 Rebuild - Ignition HELP Please!

[Tonyg11780]

Before I go and do something wrong...

I am in the middle of a tub replacement. I purchased a brand new tub to replace ours that got damaged in a collision. The new tub does not have the hole in the firewall for the MCU connector to pass through. I have an MC2150 carb and have deleted all of the smog equipment. I have also completed the nutter bypass, but I am still running the stock distributor.

Here's my question. I do not want to cut the hole for the MCU connector, and do not even want to reinstall the MCU. I am looking to eliminate as much of the engine wiring as possible, but from the diagrams I am looking at it seems I need the MCU even after the nutter bypass. Can someone tell me if I am clear to eliminate the MCU? I would like to also get rid of the ECU, but that ones not as important as I dont have to cut special holes in the firewall for it.

Thanks in advance,

TonyG

 

[Torxhead]

Doing the Nutter Bypass pretty much eliminates the need for an mcu anyway. So you might as well ditch it. The ecu or ignition control module is a critical part of the ignition system. You could even improve it by taking the black wire from it and running it directly to the battery negative. All it does is ground out the icm and doing it thru the distributor makes for a pretty poor connection.

 

[Peanut Butter]

Given what you are doing,I highly suggest you get a good wiring diagram so that you can look and see what everything does. The best I know of is found here:https://colorwiringdiagrams.com/

 

[Belizean]

Given what you are doing,I highly suggest you get a good wiring diagram so that you can look and see what everything does. The best I know of is found here:https://colorwiringdiagrams.com/

It really is a great one, got it a couple of years ago and well worth the money

 

[Tonyg11780]

Given what you are doing,I highly suggest you get a good wiring diagram so that you can look and see what everything does. The best I know of is found here:https://colorwiringdiagrams.com/

Thank you PB, that diagram looks great. I ordered the corresponding diagram for my CJ. That should really help now as well as down the road. I greatly appreciate it.

From the looks of everything now, I should be able to eliminate the MCU and all associated wiring, but I will use this diagram to chase each wire individually to ensure its not necessary. ICM has to stay until I upgrade to HEI, but thats no issue because the elimination of the MCU should drastically clean up the wiring under the hood.

Thanks to all,

TonyG

 

[Lumpy Grits]

See if this helps-
Ignition (Some Mods)

LG

 

[Tonyg11780]

See if this helps-
Ignition (Some Mods)

LG

Huge help Lumpy! That's exactly what I've been wondering...further confirming that I should be able to remove the MCU and all associated wiring with no negative impacts. Thanks!

 

[Lumpy Grits]

This is a great source of information, that you want to 'bookmark' for quick reference.
Table of Contents

LG

 

[yellow85cj]

The MCU wiring is pretty much it's own separate harness. Save one wire that runs to the relay that controls the intake manifold heater. You will want to splice that one back into the relay. IIRC it is red. The wire that powers up the MCU is also a red wire (IIRC) that comes from the engine side of the fuse box. Don't need to do anything with it except cap it.

If you take the MCU connector and start pulling the wires back toward the drivers side along with the test connectors ( the cream colored connectors on the battery brace) you will find it will come out by itself save the 2 wires. If you do decide to cut wires as you go, I suggest that each time you cut a wire, you start the engine. Much easier to find out if you cut the wrong wire.

Don't get nervous when you have more wire on the floor than in the CJ. You WILL have more on the floor than in the CJ. Along with a couple of relays and vacuum switches.