Mustang Foxbody ECU Inspection - Things to check if you suspect your ECU is in need of repair

Рет қаралды 5,749

Күн бұрын

General overview of the A9x family of ECU and a few things to check for if you suspect your ECU may be bad
These tests do not cover all the potential failure points of the ECU, but address some of the common things to look for.
This video reviews:
Testing 5v VREF
Pin 46 trace burns
Capacitor Inspection
Fuel Pump Transistor
General Transistor identification

Пікірлер: 39

@matthopkins1107 10 күн бұрын

Have to subscribe after this video

@krisf5247 Ай бұрын

Great video! Thanks for sharing

@wbrockstar9550 10 ай бұрын

Great video man.I had always thought the capacitors were the cause of the continuously running fuel pump so it's great to finally hear/see the true cause.Showing how to externally test pin 46 instead of squinting while trying to look for the burnt/ open trace on the board itself.Thanks for the great job,

@jamjr5132 4 ай бұрын

Good video!!

@Adrenacyde 11 ай бұрын

This was VERY well done!

@Mustang5L5 11 ай бұрын

Thank you!

@49Fordproject 4 ай бұрын

Very very helpful, at least from a visual standpoint. I am about to do a capacitor replacement. 92 t-bird X2P. The pinouts are different than the A9P A9L. I have an alleged A9P but the decal is gone. Is there another way to tell the code? I set it aside for now. I got it from a foxbody friend. But I'm not confident of A9P or even MAF at this point. I love these "deep in the weeds" projects. My project is a '49 Ford F1 with an Explorer 5.0 running EEC IV MAF not a drag car, just a cool old truck!

@dntlss 8 ай бұрын

Man you are a great teacher,very concise video, no music, no BS, just knowledge, i have been around these cars for decades and have 2 of them Ive had forever,on my 91 i have had some issues here lately, i do have a new engine in it and ive been having idle issues and I'm very familiar with them, when i installed my new engine i basically bought everything new, not because i like to throw parts but because ...new engine=new parts, why install a new engine with a 20 year old distributor or sensors etc ? that kinda thing. Here recently i pulled my computer for the very first time and there are a couple of capacitors that look like hell, since ive checked everything and everything is basically new with oem Ford parts i'm guessing the computer could be at fault and its time for a rebuild? i also have a very very weird problem,when it rains the car will run like crap, i dont have to drive it in the rain,just the fact it rains its enough to throw it into a a abyss of bucking and dying etc, you ever hear of a computer going crazy due to moisture? Its not the distributor, or the plugs or the mass air or the distributor boot or the oxygen sensors or the ECT or ACT or any of those things, that has all been triple checked, codes have been pulled, no codes except for a 31 and 85 which are emission related,those are the only 2 codes,thank you for any input you might have,im in the process of purchasing a used PCM that needs rebuild so i can have a spare one but mine is getting rebuilt too.

@Mustang5L5 8 ай бұрын

I haven’t heard of too many instances of moisture affecting the ECU but doesn’t mean it can’t happen. For the most part they are somewhat isolated in the kick panel, so they aren’t as exposed. However the caps should probably be replaced in general due to age, especially if they look terrible I have heard of moisture being an issue with ignition parts, specifically the PIP in the distributor. No codes, no other signs of issue but distributors should be looked at carefully, especially with the latest aftermarket parts for them being of poor quality. I wouldn’t discount ignition yet as the source of your problems

@dntlss 8 ай бұрын

Yeah that distributor is new but like you say these aftermarket parts are normally not very good specially electrical ones, the distributor was one of the few things i could not get OEM,they are hard to find these days, thank you so much for your input@@Mustang5L5

@g0e2real46 Жыл бұрын

I recently purchased a 89 5.0 5 speed convertible with a bad computer the number is E9ZF-12A650-A2A is that the correct computer for this car? And which should i replace it with if? Thanks in advance

@adamcartwright6220 5 ай бұрын

I have a car that won’t start with a constantly running fuel pump. I have no clue how to fix it so unfortunately I’ll most likely be going to a TerminatorX even though I really don’t want too. Thanks for the video. Very informative and I greatly appreciate the knowledge.

@Mustang5L5 5 ай бұрын

You could always send it in to ECUExchange for a rebuild. 9 times out of 10 the constantly running fuel pump is that capacitor off to the side on the edge of the board.

@adamcartwright6220 5 ай бұрын

@@Mustang5L5 Thank you! That’s great to know. I worry about sending it out and never getting it back or paying out the rear for it to be fixed. Thank you for the information.

@Mustang5L5 5 ай бұрын

@@adamcartwright6220 while I’ve never used them, lots of folks have. They seem to be a pretty trustworthy operation

@adamcartwright6220 5 ай бұрын

@@Mustang5L5 Thank you. I may just have to try it because I do want the option to go back to stock

@BruceWayne-te5bv Жыл бұрын

i dont have a smog pump anymore.you think i could put that transistor in place of my fuel pump one? great vid btw most informative one yet

@Mustang5L5 Жыл бұрын

The transistors for the TAD/TAB are the same p/n as the fuel pump transistor. They should interchange, but I’ve never done it so I can’t say for a fact if it would work.

@Scrapla1 10 ай бұрын

Whats the best method for cleaning off the J port at the bottom to install a chip? I have a old style chip with my tune on it and need to install it onto my new ECU which still has that coating on it.

@Mustang5L5 10 ай бұрын

I believe the proper term for it is “conformal coating”. If you search on here for “conformal coating removal” there are a few videos showing methods and solvents to use.

@heffytomad4741 5 ай бұрын

I got some questions about cel always being on, can't retrieve and codes

@Mustang5L5 5 ай бұрын

Strong indication there is an ECU issue, specifically a burned out trace for pin 46. You can pull the ECU out and check for continuity between pin 46 and pin 40 and 60.

@nothanks81 Жыл бұрын

You ever make a thread on these, noticed alot of the old big brand remans A9l's I've opened have components you normally don't see on the factory boards, traces that are normally empty with components on them. but haven't had much luck finding what they used as donors.

@Mustang5L5 Жыл бұрын

I never did one on that topic. I’ve had the same curiosity. A lot of the components inside are obsolete and tough to find the exact replacements and need to locate substitutes. I’ve just never had my hands on any of the remains to take a good luck at what was used.

@nothanks81 Жыл бұрын

@@Mustang5L5 I posted a board pic in the tfi guts thread of an old 90's town car ecu on SN.. Boards appear identical, but with more components and some chips differ but what I think the used as a core on some from others remans I've seen cracked open

@wbrockstar9550 10 ай бұрын

Interesting, I've got one in my 342ci 91LX hatch and have never bothered to pull it open simply out of curiosity, I haven't noticed any issues with it in regards to proper operation.

@dntlss 6 ай бұрын

Hey i wanted to ask a question if i may,i finally sourced a computer I'm gonna send off to have overhauled,its a A9P and from what i can tell someone replaced the capacitors however the capacitor closest to the main harness plug is different from the other 2, its really small in size from the other 2,I'm no electronics expert but sometimes i wonder why people just dont replace things with the same instead of monkeying around but again maybe it was a good idea? Also, on the big black processor on the board, they removed that rubber coating around it and i guess they were going to replace it but didn't, why would anyone do that? the reason i dont think they replaced it is because it still has the OEM processor, it doesn't look bad and the solder points look fine,the pin 46 trace is fine also, i just checked it. The guy that sold it to me is not a electronics guy, he just had a few for sale but he told me this computer comes up as a "constant prime" which I'm familiar with,he told me if its not repairable he will refund my money but as good as ECU xchange is im sure it will be fixable,i was just curious about the capacitor discrepancy and why they removed that coating of the processor? thank you for your input, i was just curious.

@dntlss 6 ай бұрын

These computers are now in their 3rd decade plus of operation with capacitors that were normally good for 15 years so most are on borrowed time,i have a 89 and a 91 and I'm trying to find at least a couple and have them rebuilt for spares,if you are planning on keeping your car act now cause they get more and more expensive and hard to find every day,you could buy them for 100 bucks all day long a few years ago, now most people want 6\700 dollars for them rebuilt @@wbrockstar9550

@matthopkins1107 10 күн бұрын

Do you recommend certain capacitors to replace these with brand wise?

@Mustang5L5 9 күн бұрын

I don't have a preferred brand but my preferred Vendors are Digikey and Mouser. I typically get all my electronics components there vs Amazon or Ebay. It's a little more $$$ but I feel better about the quality of the components those vendors sell.

@matthopkins1107 9 күн бұрын

@@Mustang5L5 even chasing idle issue for 3-4 days then after running just crank no start. Pulled ecu and capacitors are leaking 👌👌👌

@Mustang5L5 9 күн бұрын

@@matthopkins1107 At this point, i just assume every ECU that hasn't been repaired, probably should be repaired as a proactive measure. Good luck!