1989 Grand Marquis ECM removal

[friskyfrankie]

I know on the newer Fords it it a P0605. On OBD 1 it might be 15 but am working from memory so........

[monotonorobo]

The ECM from wagonman just came in (thank you again) and I put on a new solenoid since I believe my last one got fried. Tried to crank and I got a buzzing sound from either the starter or the solenoid. At first all I got was a click and nothing else. It doesn’t give out after trying to crank again like before and everything else works as well. Thoughts? Tried to send a vid but it wouldn’t let me.

[sly]

Check battery voltage under load. It may be dropping below 10V. Barring bad battery, might be a loose battery cable.

[Tiggie]

Sounds like a bad connection at the battery terminals, bad battery cable(s), weak battery, starter solenoid, or starter itself might be your issue.
I'd cross the terminals on the solenoid and see what happens. https://youtu.be/ZRlRinL-N-8?si=h6HnuVZGZz5mb_Q8

[monotonorobo]

Yeah I’ll check those too. Someone told me
to hook up jumper cables to the battery and put a ground wire on the accessory bracket. What do I do with the extra positive end?

[Hearsesrock427]

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.

Tell me more. Need parts numbers and suppliers for capacitors. How would one spec out such a job? Electronics and PCBs are far out of my wheelhouse, and will be farming this out to a posse member who does electronics repair and upgrades. Every vehicle in anything resembling active service should have its EEC board serviced, and we should probably do the digital VFD clusters too. Just to be safe.

I'm big on preventative maintenance for electronics, especially ones that are used heavily. Especially so if the vehicle in question lives outside for most of its life. The endless heat cycling plus just how old the car is, ensures this is something that cannot be neglected. From what I've seen, it would also be worthwhile to reflow the board itself with a heat gun. Recall seeing and reading about how later EEC-V boards develop small cracks in the joints, and in the interest of preventative maintenance the older boards would benefit from such a service too. See video for more info: https://www.youtube.com/watch?v=Y7azLvBMwgo

[sly]

just use the negative cable of the jumper cables and give the engine an extra ground. Make sure to keep clear of the fan and belts. This will let you know if the ground side needs help. If that doesn't help, then add the positive side from the batter to the solenoid on the fender (side closest to the battery). If that still doesn't help, disconnect from the battery and solenoid and reconnect the positive cable between the switched side of the solenoid (side away from the battery) and the positive lug on the starter.

Once you get it to start... disconnect the ground side and see if it'll start again. You may have more than one connection that's not good. Whatever is connected with jumper cables needs looked at and fixed.

[monotonorobo]

Yeah I just tried the ground wires by themselves and nothing happened. When you say add the positive side from the battery to the solenoid do you mean the positive plug with the red wire, correct?

[gadget73]

any special reason you have nothing connected to the starter side of that solenoid ? Its not gonna crank without the starter connected. Looks like the nut is off the other side, that won't work either.

[sly]

Red (+) is positive. Black (-) is negative.

And yeah... gotta have the fat cable from the solenoid to the starter connected for the solenoid and properly bolted down to allow power down to the starter. Without the nut holding firm pressure on all that stuff, power no go. No angry pixies... no motor turning.

[monotonorobo]

any special reason you have nothing connected to the starter side of that solenoid ? Its not gonna crank without the starter connected. Looks like the nut is off the other side, that won't work either.

This an old picture of it everything is already on connected to it.

[Kodachrome Wolf]

Tell me more. Need parts numbers and suppliers for capacitors. How would one spec out such a job? Electronics and PCBs are far out of my wheelhouse, and will be farming this out to a posse member who does electronics repair and upgrades. Every vehicle in anything resembling active service should have its EEC board serviced, and we should probably do the digital VFD clusters too. Just to be safe.

I'm big on preventative maintenance for electronics, especially ones that are used heavily. Especially so if the vehicle in question lives outside for most of its life. The endless heat cycling plus just how old the car is, ensures this is something that cannot be neglected. From what I've seen, it would also be worthwhile to reflow the board itself with a heat gun. Recall seeing and reading about how later EEC-V boards develop small cracks in the joints, and in the interest of preventative maintenance the older boards would benefit from such a service too. See video for more info: https://www.youtube.com/watch?v=Y7azLvBMwgo

In my experience, the original capacitors I’ve dealt with were Nichicon capacitors coming off the boards. Usually replacement ones I’ve used have been Panasonic ones since they were easier to get my hands on.

Unfortunately there’s no hard/fast rule to which specific µF (microfarad) ratings you may find on your specific ECU. I know between a LoPo and HO board they had different ratings, and even a different number of capacitors between the two. Essentially you’ll want to open up the specific board and record the µF and voltages of each capacitor. You can use a replacement capacitor with a higher voltage rating than the original, but the µF needs to remain the same.

Our ECUs are also covered in a conformal coating which needs to be removed to access the solder joints. You can get the products to recoat the board when you’re done online. I’ve personally used liquid electrical tape, but reapplying the conformal coating would look more professional.

[monotonorobo]

Red (+) is positive. Black (-) is negative.

And yeah... gotta have the fat cable from the solenoid to the starter connected for the solenoid and properly bolted down to allow power down to the starter. Without the nut holding firm pressure on all that stuff, power no go. No angry pixies... no motor turning.

Yeah I knew. just meant if you wanted me to unplug the fat red one too. I’ll mess with it in a few.

[sly]

nah use the jumper cables as a piggy pack, don't disconnect anything. You're trying to find a weak link that is fixed by adding wire to it. The jumper cables won't be able to carry the full current due to the crap connection at the jaws. Jaws don't do well conducting on bolts due to the small contact area. But it will add capacity if the wire length is partially broken.

[monotonorobo]

Got everything back together and I got spark then it went away. Changed ICM, Ignition coil, re-timed distributor, and since I got some spark plugs and wires laying around I might install those as well. Still much better response with this ECM than the last one. Could also be the distributor itself. Anyone got a link to good one?