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PCM water intrusion

283 Views 5 Replies 4 Participants Last post by  TurboGT, 
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I looked through other discussions and it doesn't look like this is a regular occurrence for these cars even though Its a terrible placement for a PCM.

After several electrical issues I stumbled upon water intrusion on my PCM on one of the sets of connectors. The PCM cover was warped which is what I'm assuming let the water intrusion occur. The PCM case however has several openings along the back side of it. I did not have a large amount of dirt or debris I'm the PCM case or any obvious signs of water.

I do not know a lot about electrical so I'm curious if the PCM is a total loss or may be able to be cleaned and repaired. Also programming will be needed for a new PCM. I've seen a couple websites where you can order modules pre programed by the VIN number but they have awful reviews. I'd like to avoid taking the car to the dealership if it can be helped as my local dealerships are backed up and indicated I have to leave the car for it to wait in line. I would also have to get the car towed at that point. I'm hoping and praying that my connectors and wiring harness will be reusable as they have very little visible damage.

Any words of wisdom or advice on the topic would be much appreciated! Also any ideas on not having this issue re occur would be wonderful. At this point I plan to zip tie the top and bottom of the PCM case to try and keep it closed. I'll attach photos of the pcm damage as well as the warped PCM case.

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junits15
So its important to note that the plastic case is not intended to prevent the PCM from getting wet. The PCM itself will be built to a standard such that it can withstand the amount of water it may see in its location. This failure is not a result of the plastic cover not doing its job, rather its a result of the connectors not doing their job.

That's a critical distinction because the only way water can reach the pins is through the connector housings, and those connectors should never allow water to reach those pins. I would inspect the connectors on the harness, look for failures in the seals. Simply replacing the PCM may open you up for this same issue again. Inspect the seals around the individual wires and around the edge of the housing.

Unfortunately I can't offer any guidance on how to program the new PCM
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junits15 said:
So its important to note that the plastic case is not intended to prevent the PCM from getting wet. The PCM itself will be built to a standard such that it can withstand the amount of water it may see in its location. This failure is not a result of the plastic cover not doing its job, rather its a result of the connectors not doing their job.

That's a critical distinction because the only way water can reach the pins is through the connector housings, and those connectors should never allow water to reach those pins. I would inspect the connectors on the harness, look for failures in the seals. Simply replacing the PCM may open you up for this same issue again. Inspect the seals around the individual wires and around the edge of the housing.

Unfortunately I can't offer any guidance on how to program the new PCM
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I will take a much better look at the connectors and add some additional photos. I was also planning on using some dielectric grease when reinstalling the PCM. I'm not sure if it's the best idea but in my mind it will add some additional water protection.
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TurboGT
Agree with the above.

Be very gentle and you should be able to clean all that stuff out. Pay good attention to getting rid of the crud that is between the pins. As you're scrubbing, see if any of these corroded pins feel weak, like they'll lay over easy. If so, replace the PCM.

Either way, I recommend buying Stabilant-22 and using that instead of dielectric grease. It's a connection promoter that was originally designed for military aircraft. No failures at 30,000 feet!

As far as getting the PCm programmed. I used a company called AsTech that does mobile programming and they have several locations Nationwide. The only downside is you, the consumer, can't set up an appointment. You have to have a shop call and schedule them. Any auto repair shop can set up an appointment.
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rambleon84
TurboGT said:
As far as getting the PCm programmed. I used a company called AsTech that does mobile programming and they have several locations Nationwide. The only downside is you, the consumer, can't set up an appointment. You have to have a shop call and schedule them. Any auto repair shop can set up an appointment.
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When i was gong though my issues i did look into swapping out a new ECU, there were companies that claimed they could send you one programmed ready to go based on your VIN and others that said you could send them yours for repair. I didnt get further than looking them up though, my ECU turned out to be ok afterall.

EX, this matches the part number listed on the OP's unit: EM5A-12A650-PC | 2014 Ford Focus 2.0L PCM Engine Computer ECM ECU Programmed & Updated | BB5A-12B684-AC

The price isnt very nice...they list other focus ecu's for under $200
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TurboGT
@rambleon84 I think between buying the junkyard PCM and having it programmed I was somewhere in the neighborhood of 300. A new PCM from ford is 1,100 plus programming. So I don't consider 500 to be that far off-base.
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