View Full Version : HELP! Where is engine harness and ecu??!! 90 SC

06-18-2017, 12:51 AM
Hello all. I'm new here and I'm sorry but I suck with computers. So, I am currently swapping my SC motor into my foxbody Mustang. T-bird was a blast but the body is falling off of it and the drivetrain needs refreshing ayways. It's a 1990 SC with a 5 Speed. I currently have it on my hoist with the entire subframe unbolted and separated from the chasis but.... There is that damn harness holding it in. How do I get at the ecu? Do I need to remove the dash? I'm sorry to say I am not a ford guy but I am a competent backyard mechanic. As far as my swap goes I'm just removing the entire harness and every wire from the bird and putting it back together in the mustang. I know a lot doesn't work from car to car but I can delete things as I go and want to start with the complete setup. My mustang was a 2.3 auto Convertible and since I bought both cars and drove both of them for under $1000 I'm just using what I have laying around. Please if anyone has tips on how to get that harness out it would be great. I really don't want to cut a factory harness if I don't have to! Will have more questions on motor build later on. Thanks

06-18-2017, 01:08 AM
I'm not clear on which harness is giving you trouble.

The engine side of the main engine harness connects at the firewall, behind the pass. side wheelwell - might help to remove the wiper cowlings to make room. There is also a large round white bundle connector on the left side, again, behind the wheelwell.

Might be simpler to pull the harness from the engine - mark as best you can and take lots of photos.

SC ECU is behind the passenger side kick panel, inside that end of the dash. First remove the passengers side kick panel. Then remove the glove box. Using a 1O mm socket remove the one nut holding the ECU's wiring harness to the ECU. A white plastic bracket will be holding the ECU in place. Remove the one screw holding the ECU in place. Pull the ECU down and out.

06-18-2017, 01:15 AM
It sucks cause I can't open the doors as it's lifted on the hoist. But I did remove the glove box and kick panel. I guess I will keep digging in there. Hard to get in and out since no power but at least windows are down to slide in Nascar style. I will check behind the insulation. Do you know if there is room to pull it thru or does the dash have to come out? Thanks

06-18-2017, 01:30 AM
If you mean pull EEC thru the firewall, no, not without surgery. Harness, maybe.

Edited my original reply w/more info on removing the ECU.

06-18-2017, 02:41 AM
IT CAN BE DONE!!!! Wow! after crawling in the window and leaving my footprints all over the ceiling you can tuck your head under the dash and undo the connectors and that 10mm bolt (don't forget the tiny ground wire, oops) and then pull and prod and pull and fight like hell but they all do come out of that tiny hole!!! But... Then I found the wires also ran to another ecu in the rad support. But the car has been lifted off the engine like it went in at the factory. Thanks so much for getting back quickly with that ecu location. Now I can call it a day and clean up. 12:30am here.

06-18-2017, 10:13 AM
The 'other' would be the IRCM. Integrated Relay Control Module - holds relays for fan hi/low and EEC power.