wbrockstar

0.5 ohms means the wires are not shorted or open.

If tapping caused the relay to turn on or turn off,I would make sure the harness plug wires aren't loose,corroded or pulled out of the plug.It shoudnt turn on/off by tapping it.

A computer store and some cb radio repair shops (sometimes located close to truck stops) can replace/repair capacitors/signal return trace.If one cap is bad,go ahead and replace the other two also because they won't be too far behind given their age.I haven't found the part number for the 10μf 63v capacitor yet,but the following link is the 47μf 16v cap part number.You can also use a 47μf 35v cap,if the 16v one isnt available. The 10μf 63v can also be replaced with a 10μf 35v cap,if the 63v one isnt available. You can search the site for the other cap I listed above.
https://www.digikey.com/product-deta...6-1-ND/4319809

(Cap replace)
tp://support.moates.net/capacitor-repair-ford-a9l-ecm/

john89gt

wbrockstar

If you don't feel comfident in your soldering skills,you could go ahead and buy the new/reman ecu,but for an hour or two of your time and $10 in parts,its worth trying to repair it yourself,right??Youve got nothing to lose at this point and your check with your buds good ecu is verification its the ecu at fault.Keep in mind, there could be other things wrong too like a burnt signal return trace so check for that also.Its also best to replace all 3 caps while you're there because they're either bad too or will be shortly.If you do decide to try it,carefully wipe the clear resin off the board area with alcohol where you're making the repair.Check both sides of the board also as one side might not show damage while the other side will.
There are a few ecu repair companies that list a ecu repair service from $115+ on Ebay too,you could check out,but you'd have to wait on them to fix it and send it back which means an unknown turn around time..With the thousands upon thousands of 89+ Mustangs being 30 years old,the demand for ecu's is quite large since the capacitors begin leaking and going bad at 30 years,so Ive seen guys listing these things for $300-$400 ,trying to take advantage of the lack of supply,when in most cases the capacitors,a burnt signal return trace or possibly a bad transistor,is the only thing wrong with the ecu.Unless they're searching on forums like this,alot of guys/gals arent even aware that the ecu usually only needs $10 worth of parts to repair it,or sometimes no money at all in the cases where the signal return trace got burnt due to mistakenly connecting the battery cables reversed or using the hood light terminal instead of the sti terminal to run code tests or using the wrong o2 sensor harness,etc,etc.In these cases,a 2" long piece of 30ga wire soldered across the burnt trace is all that was needed and these people went out and spent hundreds of bucks on a new ecu.

The following link shows a few ecus being repaired.There are youtube videos too that detail ecu repair.


http://sbftech.com/index.php/topic,37389.0.html

john89gt

Wbrockstar-Definitely right about nothing to lose. Is there a special type of solder needed for this application? I asked the manufacturer of the capacitor and one said "leaded" and the other said use "lead free". How confusing is that? Does it matter which type of solder you use? Sorry for all the question. I just want to make sure its fixed to last and not a patch.

wbrockstar

I was just trying to find some info on ecu repair and found the part numbers for the capacitors needed.These are available at Mouser according to the poster.
(Quantity 1)
647-UKA1C470MDD1TD
Nichicon Aluminum Electrolytic
Capacitor-Leaded
( Quantity 2)
75-511D106M063AA4D
Vishay Aluminum Electrolytic Capacitors-Leaded

Youll need a solder sucker.It basically removes the old solder from the board,so the contact area will be clean when you solder the new caps in place.You also don't wanna overheat the board & the solder sucker will remove the old material quickly vs constantly having to re-heat the board to do so,without one. The new caps have 'leaded' in their part description,so I would say leaded solder should be ok.If the caps arent available in the exact voltage rating you need,you can use a cap with a higher voltage rating,if the 16v or 63v cap isnt available.Just keep the μf number (47/10) the same.

wbrockstar

I was reading a thread earlier talking about ecu repair.Is the capacitor on your board,thats bad,the 10μf 63v one??If yes,its the cap out of the three that causes the continuous fuel pump run on & the check engine light to remain steady on,when the key is on and the jumper is connected for the purpose of running the code tests.Be sure to check the trace directly under the bad cap that the cap posts are connected to,for any acid that may have leaked out onto the trace and damaged it.Repair it if needed.The following paragraph is where the info above came from.

"I missed the trace on the circuit board when I replaced the 10uf capacitor! Repaired the trace & all is well! Cranked right up and runs great as always. The fuel pump NOW only runs it's initial 2 seconds and stops and the MIL doesn't stay on, so you can now check codes.
Evidently when this 10uf Capacitor fries the negative lead, it also takes out the trace!This is something everyone with a A9L or A9P eec needs to know!

john89gt

Wbrockstar-Thanks for all the great info. Sorry for the late response, but I've been a little busy with work. I've dropped my ECU off by a local computer guy. He said he's repaired a few over the last couple of years, so hopefully everything turns out great. It sounded like it would be around $35 to repair. I'll keep everyone posted on how it turns out.

wbrockstar

That's a great price if it turns out being the final cost.Definitely keep us posted and good luck with it.

john89gt

UPDATE- I had the capacitors replaced with no luck. I plugged the computer back in and the fuel pump still runs continuous. Wbrockstar-do you have any pictures for the trace on the circuit board or the link to the post you referenced?

wbrockstar

Here are pics of the burnt trace and it's repair.Check both sides of the circuit board too.




Make sure the areas on the board where each capacitor was replaced doesn't show any burnt/damaged traces either.I assume the guy that repaired your ecu soldered each cap in with the correct polarity on the board.IOW- there is a + & - on each cap post.Just look at your caps and make sure they are orientated correctly,using the cap stripe & the pics in the link below as your guide.The stripe is black on the oem caps.
http://sbftech.com/index.php/topic,37389.0.html

After you inspect/reinstall the ecu,try tapping the fuel pump relay again or put the old one back in and do so,since you made a previous comment about the relay changing its on/off state from tapping on it.Make sure none of the relay wires are suspect (loose/corroded) where they push into the harness plug.

I was gonna advise you to test the wiring for pin 22,but if your friends ecu got it running again,then it's gotta be in the ecu.If you can borrow that ecu again to plug in and if everything is running fine with it in place,then it has to still be something inside your ecu causing the issue.You might just have to bite the bullet & get a remain ecu,if you don't find anything else wrong with yours like damaged traces or backwards caps.When one of those caps is leaking onto the board,it can eat up some of the trace,which can be repaired just like the signal return.