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1996 F350 5.8L AOD. Driving down the street and it just died.
Cleaned the terminals at the distributor pigtail and replaced the spark control module. It runs, but poorly with no power and a lot of misfires. 40 mph top speed.
So yesterday I pulled the ECM and found this:
What could have caused this?
Sure looks to me like something pulled more current than it was made for.
I have a Cardone reman ECM on order. While I wait for it, I'd sure like to determine whether something else has failed and cause this ECM failure.
Any suggestions welcome.
I don't know the circuit lay out, but I would hazard a guess that the problem began with the capacitor leaking acid, damaging the board and causing a short. Components drew power they weren't designed for or incorrect polarity, heat up and combust.
Assuming nothing outside the EEC was involved...
Someone who knows the circuit lay out would be able to provide more educated speculation.
The damaged area is around a large diode that is there primarily for reverse polarity protection at the battery input of the ECM. Now, why it has blown is a good question and as this happened while driving, it would seem extremely unlikely that somebody switched the battery terminals around.
What I would look for is alternator problems, possibly a shorted diode or faulty regulator.
I am quite curious as to why there are two smoked areas on the right side of the first picture. Was there another damaged area? It becomes quite difficult to relate the picture of that cover with the damage shown on the circuit board.
Inputs and outputs are quite well protected in the ECM and any stray voltages introduced would be through physically damaged wiring. Look for any obvious signs of damage in your engine bay, but such a failure would be extremely rare.
Get your hands on a pin out for the EEC connector and check every wire in the harness for shorts. This will also help you to find any downstream components that are shorted out (cause or effect ) Repair and replace as necessary. You may still have damaged components that are not shorted but cause drivability problems that will have to be diagnosed with a EEC in place.
If you knew which circuits on the board were burnt that could help direct your troubleshooting. Edit - NotEnoughTrucks may have given you the clue you need to direct your efforts.
Or roll the dice and replace the computer and see what happens. If it was capacitor failure then you may still have damaged downstream components that will show up. If the problem was caused by something outside the EEC it will recur and you will have to dig deeper.
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) Repair and replace as necessary. You may still have damaged components that are not shorted but cause drivability problems that will have to be diagnosed with a EEC in place.
