I'm trying to wire up the stock check engine light to the output from the Accel DFI unit. The car used to have the LG4 and I have since removed the old computer and now use the Accel system to control my 383. The light currently stays on all the time and it would be nice to have it actually function with the new system.

The wiring harness from Accel has a two pin connector off the computer for the MIL (malfunction indicator lamp). The wiring diagram says that the two wires are:

Pink, for the 12v to the light
white, MIL signal

Now from the dash / connectors to the old computer (see attached picture). I think what I need is in the 7 wire connector. I believe the white/green stripe wire is to the MIL light.

Since the light is currently on, I would imagine it is getting the +12V. So I believe all I need to do is connect the white/green stripe wire from the old harness to the white wire on the Accel harness? Is this right?

Any help is appreciated. Thank you

 

Alright, well I found out some new information after searching around more.

There is a light driver module that acts as a switch for the SES light. The white/green stripe wire is used to send the signal from the computer to the LDM which then grounds the light to turn it on.

From the Accel computer, there is a trigger wire which does the same thing. I was thinking the MIL connector was it, which it is not correct.

So what I need to find out is what signal level the Accel computer puts out and will it work with the stock LDM. I'm going to put a temporary wire between the two and see if it works.

 

Did you get this sorted out? I'm getting ready to do the same thing to my car.

 

I'm in procress of installing EFI in my 84 TA. I have an aftermarket wiring harness also. I was told the wire on the harness is a ground from the computer (inside the ECM). I want my factory setup to work without hacking everything up.
So I took a stock bulb connector (the green thing that bulb plugs into) and sliced it down the sides where the copper contacts are. A single edge blade works fine. Look inside you will see where the copper stops. Remove enough green plastic to pull the copper contacts to the bottom. I then put some tape on the inside where I just cut both sides out. Then filled the space with hot glue. I then soderd 2 wires to the 2 copper contacts and sealed the outside of the socket.
The other wire goes to power that works when ignition is on, as stated before the wire from harness.

NOW I know the bulb works because I reinstalled it and tested it by putting a hot and ground to it. I have not finished the EFI install and have not run it with it hooked to the computer.

 

I did exactly what larry did to get my ses light to work, it is a active low.

After finishing the wiring, and installing the center console I somehow messed with the brake switch, now that light won't go off