1989 Grand Marquis ECM removal

[monotonorobo]

Yeah so I took off everything on the firewall side and messed with some stuff by the pedals and can’t figure out how to pull it out. It’s stuck on the bracket with those two plugs and I removed some nuts and no budge from that bracket. I got lost on something simple. Anyone know how to pull it out?

[friskyfrankie]

Not sure on the 89 but I believe the older ones have a plastic clip that the ECM mounts to. Can't tell from the photos as the wiring may be covering it. Someone here will know if this is true, for this model year, or if there is another way it is attached.

[sly]

push the ECM to the left to clear that little bracket it sits in and pull down towards the floor as hard as you can as you pull in to the car slightly. It should JUST clear. It should be mounted in a rubber seal at the firewall that is very tight and doesn't like to let go, but it will.

If you run into the cornering light relays (metal cans) and can't clear those, remove them from the bracket by removing that screw holding the tabs on the top of them.

[monotonorobo]

Thanks, I’ll mess around with it in the morning. I’ll also send pic of the ECU when I open it up because I believe it’s a failed capacitor cause the EEC isn’t working.

[monotonorobo]

Apparently the screws are stripped bad and stuck on the ecu so I can’t get the cover off. Would it be safe to assume that that the ecu was one of my issues? I’ll give a rundown real quick. Car sat for few years and I replaced a lot of things and when I got it running finally it ran great for about a month before I started having idle issues. I changed the ICM but two days after that it died on me so I thought my timing was off. Set the timing, ran great for a minute then just shut off. Fuel pressure was 35-40 psi as well. Tried to crank it up again only for me to get either a quick little bump from the starter or a struggling sound from it. Changed the starter and the solenoid as well so it wasn’t that. Tried to do the EEC test but no response thus me believing that it is the ECM. If I do get another where would I find one at? eBay?

[monotonorobo]

Also occasionally had a burning smell after a long drive too on the drivers side.

[WagonMan]

There are a few decent vendors on this site. I have been selling parts to members here for many years. I have a mint ECU with the same part#. $50 plus shipping.
I only sell to U.S. locations, I do not sell internationally. U.S Money order only. No Paypal. WagonMan VEIGHTPETE@GMAIL.COM

[monotonorobo]

Sounds good. I’ll get back to you maybe later on today. Do you also happen to have any OEM distributors for the 302?

[WagonMan]

No distributors at this time. WagonMan

[monotonorobo]

Sent you an email, get back to me when you can, thank you.

[Kodachrome Wolf]

Apparently the screws are stripped bad and stuck on the ecu so I can’t get the cover off. Would it be safe to assume that that the ecu was one of my issues? I’ll give a rundown real quick. Car sat for few years and I replaced a lot of things and when I got it running finally it ran great for about a month before I started having idle issues. I changed the ICM but two days after that it died on me so I thought my timing was off. Set the timing, ran great for a minute then just shut off. Fuel pressure was 35-40 psi as well. Tried to crank it up again only for me to get either a quick little bump from the starter or a struggling sound from it. Changed the starter and the solenoid as well so it wasn’t that. Tried to do the EEC test but no response thus me believing that it is the ECM. If I do get another where would I find one at? eBay?

Of the two bad EEC-IV ECUs I've replaced, I always wound up with no communication from the output pin on the OBD connector. One was a Mustang, and the other a Ranger, and both never would enter self test when the pins were jumped and the output pin always remained grounded. The Mustang one did have bad capacitors, but even after a recap job, it wasn't resolved and needed a replacement.

ECU is usually the last thing I'll condemn, but given the age of them, unfortunately those capacitors are the weakest link now. If preemptive steps are taken on good working boards and recapped prior to failure, I'm sure an ECU will keep working another 20-30 years before it needs that again.

[gadget73]

yeah the caps do fail and leak crap into the boards which rots the traces. Not great, but not hard to fix. Like he said they tend to be pretty reliable but this stuff is all just so old at this point in time.

[sly]

The original ECU I had from the Mark VI had a burned diag pin (wouldn't talk... found out that pin was fused right next to the processor) but it still worked. Swapped in another one that would talk so I could get codes when having issues. When I sold it, I passed the original ECU on as a "just in case" unit as it would run the car. But yeah... usually when they won't talk, they're completely fried.

[monotonorobo]

ECU won’t tell you when something’s wrong with the ECU. Hopefully the new one will fix my idle issues and I hope I don’t have to get another pickup coil. If I do then it is what it is.

[gadget73]

There is actually one code for ECM ROM failure but I don't know that I've ever heard of someone getting it.