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Seemingly "non-existent" mosfet problem


Maseman__46

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Well, it's been a while since I last posted, and my issue got resolved rather quickly. Not sure if this is the correct section, but I didn't feel like it fit into any others. So, after several days of searching (and reading countless data sheets and such) I seem to have some kind of mosfet or voltage regulator that doesn't exist. My friend took her ranger to a really shady mechanic, and he replaced all the fusible link(s) with regular wire and no fuses. Which, incidentally, blew off a few traces (which has since been remedied) and this... Thing. I think its a voltage regulator as it's tied into the main 12v supply, but I'm not 100%. From what I can read, i believe the number is O4S47K, but that doesn't seem to be valid. I'm just hoping someone has come across this and knows an alternate part that can be used, or just knows what it is exactly. A new or used Eec module is out of the question as money is an issue currently, but I do have a large amount of junk electronics to salvage from See pics below for specific info. Thank you all in advance!
 

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Rock Auto 5% Discount Code: 7FA902352B4C01: April 5th, 2021

broncc

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Ford has a really nasty habit of paying manufacturers to put junk part numbers on all their packages to make repairs like this significantly more difficult. I'm actually fighting this issue right now repairing my radio... I'd suggest continuity testing from each pin of the Motorola "thing" to the DIP packages on the board. If you beep out its a 5v regulator. Just replace it with something that seems reasonable. If the continuity tester beeps out to the pins of the main connector then its a FET, probably n-channel.

The only significant power the ECU would sink would be auto shift solenoids on 52&53 and injectors on 58&59.
 

19Walt93

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They're not junk part numbers to make DIY tougher, they're manufacturer ID numbers. Even Ford dealers don't open PCM's because no diag info or parts are available. Anyone who would put wire in place of a fusible link isn't a mechanic, he's an idiot.
 

broncc

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I really wish that were so, but I'm convinced its to make reverse engineering and repair of the circuit more difficult. I can clearly see on OP's component that its a motorola chip made on the 2nd week of 1990.
In my radio all the ICs are labeled 700XXXX independent of whether its a STmicro, Phillips, or Signetics chip. Both still have the brand mark and date code legible. All the ICs in my RABS box are all national semi but use 7X001 naming wtih datecode in 89. I think the micro is a COP8 series mislabled as N7600010fjc003.
 

Maseman__46

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Looking at the A9L unit pictures I have seen, it shows that one as the ISC driver, but it doesn't seem to be tied into pin 21.

19Walt93, that wouldn't surprise me in the slightest actually. I've repaired quite a few harbor freight vulcan welders and I've across the same issues. Though I will say that most of the parts are good name brand stuff, just different numbers. So that helps


Broncc, As far as testing the pins to the board, I'm not quite following you on that one.
 

broncc

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Sorry for not being clear. With your multimeter in continuity test mode, hold one probe to each of the three legs of the mystery component and touch each leg of the other ICs on the board. If multiple ICs beep out (usually the corner pins) its likely a voltage regulator. It might also beep out to 1, 37, 67 of the main connector, which are 12v input pins. If the center leg of the mystery component only beeps when you touch a single pin of one of the other ICs its likely a FET. To confirm this one of the other legs will beep when connecting to ground pins 16, 40, or 60. The remaining pin would have continuity to 52, 53, 58, or 59.

At least thats what I would do. I am certainly no expert on this topic.
 

Maseman__46

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Alright, I'll give that a try and get back to you. Thank you
 

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What your holding is a transistor, its an electronic switch. You can find them online or any electronics store.
 

19Walt93

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I really wish that were so, but I'm convinced its to make reverse engineering and repair of the circuit more difficult. I can clearly see on OP's component that its a motorola chip made on the 2nd week of 1990.
In my radio all the ICs are labeled 700XXXX independent of whether its a STmicro, Phillips, or Signetics chip. Both still have the brand mark and date code legible. All the ICs in my RABS box are all national semi but use 7X001 naming wtih datecode in 89. I think the micro is a COP8 series mislabled as N7600010fjc003.
PCM's are emissions components so dealer could get in hot water messing with them. Ford gives no thought to anyone trying to fix old cars, they want to sell a new one. They also don't spend a dime trying to prevent people from fixing them.
 

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Good luck with a proprietary marking part like that - you'd have to almost reverse engineer the circuit to figure out what is needed. Testing the existing part won't mean much since (I'm assuming) it has failed. You'd be far better off getting another unit at the junkyard, even if just for components.
 

Maseman__46

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Shadowrider6661, That's exactly what I'm trying to determine. It's just a to-220 package, so it could be a mosfet or a voltage regulator. If it is a mosfet, there's like a billion different ones 😂 I was just hoping someone had come across a similar problem, or knows what circuit that's for
 

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Barring someone coming on here with a working example of that same unit who can probe the circuit and tell you what it is, the only real way you're going to find any clues, is to (like said) closely examine the surrounding circuits that particular component interconnects with.

You mentioned it was interconnected with the 12V input supply... In the usual case of a TO-220 voltage regulator, you should find pin #2 to be grounded, and pin #1 interconnected with the 12V supply. Pin #3 would then branch off to the various input (+VCC) pins of surrounding ICs and other circuits. This isn't a guarantee though (as an example, I've seen instances of a diode placed in series with pin #2 used to boost the regulator's output voltage by 0.7V). Failing that, there is no good way for any of us without that same unit to be able to determine what it is, because indeed that part does appear to be "house-marked".

Also FWIW, it could very well be a BJT too (bipolar-junction transistor).
 

Maseman__46

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4x4junkie, I will definitely do that as a sanity check, thank you. The detailed explanation is much appreciated. After several more hours of looking (too much free time at work 🤣) I found a schematic though. Here it is if anyone is interested. Thank you all very much!
56677
 


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