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Anyone ever repaired a K car SMEC controller?

Moparnocar

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My sweet 87 New Yorker, with a 88-89 ish MPFI 2.5 ( installed by someone else) left me on the road for the first time, just killed while driving.

I narrowed it down to no ground signal from the SMEC ( computer) I grounded the fuel pump relay/ASD relay ( powers both) and got power to the fuel pump, coil, etc, and it started

Then of course, the ground signal magically came back, and works fine

I will be inspecting wiring closer, but my question is:

Anyone ever opened one up? The actual ASD signal is supposed to be built in to this model. I'm wondering if there is some common failure inside I could easily see

Due to low quality of rebuilds, I don't just wanna put a new one in. And I don't want to spend any real money on this sweet ride.

TIA
 
these were common to go bad back in the day . the a.s.d relay internal of the controller is i a jell type covering and we did wire some of them with an external relay but that was 25 years ago. these cant be to much money now see what A-one cardon has or junk yard the weather i.e moisture was the problem shorting out the circuit board.
 
these were common to go bad back in the day . the a.s.d relay internal of the controller is i a jell type covering and we did wire some of them with an external relay but that was 25 years ago. these cant be to much money now see what A-one cardon has or junk yard the weather i.e moisture was the problem shorting out the circuit board.
That was my idea, just ground that wire into the fuel pump relay with another relay, that will work?
 
That was my idea, just ground that wire into the fuel pump relay with another relay, that will work?
i would check the wire diagram to see how it is wired then add relay as needed. you may be able to have key powered relay to make ground for fuel pump you dont want to back feed a circuit to short out more of the smec
 
Reflow solder on the molex pins and drive on.
 
Billccm is on it. Common ground fault.
Where is this fault? The ASD relay in the SMEC? I cleaned/replaced the ground behind the engine. If inside, fairly easy to spot?

I lost the ASD power to coil etc, and driver to fuel pump relay

I did not have a code 42, did have code for air temp and coolant temp sensor tho, both powered by smec
 
Those cars could have an internal or external ASD relay depending on build date, I believe. Distributor pick-up signal must be present to activate relay, either way. Pick-up's were common to fail, also. Have also seen wiring problems cause this problem. If you end up wiring in a relay, if internal and bad, just remember that fuel pump will continually run with key on, as in the case of an accident , even though engine quits, unless you wire it correctly.
 
Those cars could have an internal or external ASD relay depending on build date, I believe. Distributor pick-up signal must be present to activate relay, either way. Pick-up's were common to fail, also. Have also seen wiring problems cause this problem. If you end up wiring in a relay, if internal and bad, just remember that fuel pump will continually run with key on, as in the case of an accident , even though engine quits, unless you wire it correctly.
The whole car is a mis mash,

I think it has the internal ASD and external fuel pump.

I'm thinking computer because even on key up, the fuel pump relay wasn't triggering for 2 seconds like normal, untill I grounded the relay to the car, then it would work right

Yep, kinda scared of the pump running in a accident. Hoping I can open the SMEC and see the issue.
 
All the pics I find online, show the boards covered in potting material. Good chance I'll see some physical damage pointing me in the right direction?
 
Does SMEC stand for
Slow
Mopar
Engine
Controller ?

:bananadance:
 
Those cars could have an internal or external ASD relay depending on build date, I believe. Distributor pick-up signal must be present to activate relay, either way. Pick-up's were common to fail, also. Have also seen wiring problems cause this problem. If you end up wiring in a relay, if internal and bad, just remember that fuel pump will continually run with key on, as in the case of an accident , even though engine quits, unless you wire it correctly.
Just had a idea, I could wire in a Ford style inertia switch, to shut off fuel in an emergency, right?

Doing it this way seems more reliable than taking a chance on a rebuilt computer
 
The logic module actually monitors dist. pick-up signal, and if good, then sends a ground signal to power module thru a dark blue/ yellow wire at pin 5 of 12 pin connector at power module, for ASD relay activation. As you crank engine, if you have a ground signal on that circuit, you know logic module and related wiring are all good, and ASD relay is probably bad.You must check all power and grounds to power module to verify that. Where/What exactly are you grounding to make engine run ?
 
The logic module actually monitors dist. pick-up signal, and if good, then sends a ground signal to power module thru a dark blue/ yellow wire at pin 5 of 12 pin connector at power module, for ASD relay activation. As you crank engine, if you have a ground signal on that circuit, you know logic module and related wiring are all good, and ASD relay is probably bad.You must check all power and grounds to power module to verify that. Where/What exactly are you grounding to make engine run ?
I'm grounding the dark blue yellow wire. I grounded it, then the fuel pump ran. I then turned the key to "on" and got a ground signal with a power probe AFTER I had grounded it, then removed the ground. It then started.

I had checked that wire multiple times at the relay, and had nothing on key up or crank, till I grounded it, then removed that ground
 
I would want to know if you have spark and injector pulse when it won't start. ASD relay controls all three. If you do, and are only missing fuel pressure, then ASD is OK and you probably have a wiring problem (the db/yellow) between power module and fuel pump relay. Also possible, if you have spark and pulse, is maybe an intermittently bad fuel pump relay. You may be jarring it enough during ground testing, that it will suddenly work for a time or two. BTW, I believe the way the ASD controls spark is by power supply to ignition coil, so that should be an easy check.
 
I would want to know if you have spark and injector pulse when it won't start. ASD relay controls all three. If you do, and are only missing fuel pressure, then ASD is OK and you probably have a wiring problem (the db/yellow) between power module and fuel pump relay. Also possible, if you have spark and pulse, is maybe an intermittently bad fuel pump relay. You may be jarring it enough during ground testing, that it will suddenly work for a time or two. BTW, I believe the way the ASD controls spark is by power supply to ignition coil, so that should be an easy check.
Thanks for the response

I plan on doing that, I noticed no fuel, so that circuit was the first I checked. According to my diagram, the fuel pump relay powers the pump and coil, injectors etc

I just wired in a relay to ground the dark blue/yellow wire on key up/run. I did this to confirm that's were my problem is at. I planning adding a Ford interia switch to shut off fuel in a accident

I was able to access the dark blue/yellow wire and key up power to through the diagnostic connector
 
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