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Discussion Starter #1
So, I have a '93 3.8LX and I keep having this problem.
Happened a few years ago with no clear cause. Replaced the fuse and I kept going.
Last year, it happened a few times and I localized it to the MAF sensor circuit. I replaced the MAF sensor and that seemed to fix it.
However, it is happening again. Disconnecting the MAF sensor does not seem to solve the problem.
Does anyone have any experience with this kind of problem? I really do not want to have to test every wire. I recently got a new car and am debating if this is worth it.
I am attached to the bird but my free time is limited. It has 128k miles. Should I forget it and sell/part out the car or keep it and gradually try to work the bugs out?
Thanks for any help you all can give me.
 

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Any codes?

No?

Perhaps the "Powertrain Control Module" (PCM, what is sometimes called the ECM) has an internal bad connection and/or short causing the fuse to blow. Seems like if this was the case tho' a code for a bad PCM would come up. At least one would hope.

So to some extent I want to suggest replacement of the PCM.

The other possibility, as you know (ugh) is that there is a short in one or more wires going to or coming from the PCM.

I would start with the main power wire that the fuse itself is connect inline with going to the PCM. And bad wires going to the heated O2 sensors.

Then, if that isn't the problem divide and conquer my friend.

With a good wire diagram, disconnet the battery negative cable, and disconnect the pin connector at the PCM, and use an Ohm meter to check for CORRECT continuity at the pin connector to the corresponding female plug in sensor or output componet.

If a casing on a wire has rubbed off, and exposed bare wire to ground you may also read an infinite Ohm reading from that wire to the body of the car.

In the end a visual inspection of all wires may be needed.

Lee.
 

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Discussion Starter #3
Any codes?

No?

Perhaps the "Powertrain Control Module" (PCM, what is sometimes called the ECM) has an internal bad connection and/or short causing the fuse to blow. Seems like if this was the case tho' a code for a bad PCM would come up. At least one would hope.

So to some extent I want to suggest replacement of the PCM.

The other possibility, as you know (ugh) is that there is a short in one or more wires going to or coming from the PCM.

I would start with the main power wire that the fuse itself is connect inline with going to the PCM. And bad wires going to the heated O2 sensors.

Then, if that isn't the problem divide and conquer my friend.

With a good wire diagram, disconnet the battery negative cable, and disconnect the pin connector at the PCM, and use an Ohm meter to check for CORRECT continuity at the pin connector to the corresponding female plug in sensor or output componet.

If a casing on a wire has rubbed off, and exposed bare wire to ground you may also read an infinite Ohm reading from that wire to the body of the car.

In the end a visual inspection of all wires may be needed.

Lee.
I tried to get a code but I see to have an issue finding someone with a machine than can read the check engine light code for that year. The light is not on in this case.
The O2 sensors are new and I know the wires are good. I have been looking for the short but no obvious source yet.
I have been looking for that elusive short, it just takes a long time to go through all those wires and I have little free time. I was hoping a recurrent problem within that circuit was known to the forum.
 

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I tried to get a code but I see to have an issue finding someone with a machine than can read the check engine light code for that year. The light is not on in this case.
The O2 sensors are new and I know the wires are good. I have been looking for the short but no obvious source yet.
I have been looking for that elusive short, it just takes a long time to go through all those wires and I have little free time. I was hoping a recurrent problem within that circuit was known to the forum.
Yes, tracing all those wires for a short is very time consuming. Hopefully someone on this site who has had the same problem will post.

Maybe a service writer, or tech at a Ford dealership might recall a solution.

If you do discover anything I'd like to know what you find.

Lee.
 

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Ive had a few 93`s and had some issues but not the ECM fuse but the wires on the passanger side right next to the exhaust can fall down and short or the under the drivers side carpet the connectors corrode. On a side note I have a known working PCM from a 93 v6 na for sale for $20 plus shipping so you could try that if you cant find a problem with the wires. Mark
 
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