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Discussion Starter #1 (Edited)
(EDIT: Through my limited knowledge I referred to this as a computer, It is actually the SJB, or Smart Junction Box.)
(Thanks NastyStang113)

I've recently purchased a 2006 Mustang GT.
With 57K miles on the odometer, I knew there may be a few unseen issues.
After taking delivery of the car in the middle of March, It soon developed problems.
I started the car one day after it had sat in the garage overnight, and immediately the guages started acting crazy. The car was fine the night before when I had parked it, but I had driven it in the rain. Now the fuel gauge would go to empty, the backlight for that guage would go out, the low fuel warning chime would start sounding, then the info center warned I had low fuel, then it would work fine while another guage went through this same routine, then it would work fine and another would do the same thing. The traction control indicator on the dash was on, the antilock brake indicator was lit, the turn signal indicators in the dash would not function, but the turn signals worked, and the information center kept telling me to check engine, low coolant, low fuel, etc.
I shut the car off, did some searches online and found others complaining about similar issues, some were more severe, car not running, etc., while some were less severe, only one guage affected, etc.
Some of the things I was reading online eluded to a water leak on the passenger side with water coming in onto the floorboards via the kick panel.
I decided to investigate and after removing the sill plate and the kick panel, I found the computer and noticed it had small droplets of water around the connectors. Further investigation revealed water around the seam where the two halves of the computer came together. I decided to remove the computer.
After disconnecting all of the connectors, I removed the bolt at the bottom holding the computer in place. I noticed the computer had a warning molded into the plastic which said; "Scrap if Dropped". I carefully split the case on the computer which exposed the circuit board inside. There were traces of water inside.
I grabbed a hair dryer and carefully dried the circuit board and all of the connectors which connected to it.
I crawled under the dash and looked up behind it, I noticed a wire harness entering the passenger compartment just above the location where the computer was mounted and found water trapped between the wires.
After removing the grommet, I dried the wires and investigated the situation.
The grommet is an oval shape and is split on one end to facilitate easy installation. The center has an opening which didn't look like it would seal very well and the grommet itself did not appear to fit very snug in the opening at all. I think the water was following this harness inside and then dripping on top of the computer.

I thought of a few possible solutions and decided to use expanding, sprayable, foam insulation to fill the void inside the hole around the wire harness, with the hopes that once it expanded, it would also fill the gaps between the wires.
I then re-installed the grommet and sprayed some more foam inside the center hole all around the wire harness.
After remounting the computer and re-connecting all of the wires, I then took the piece of foam that had covered the top and front side of the computer and made sure it was under a drip rail which was molded into the body just above the computer. I then sealed the top edge between the drip rail and the foam with duct tape.

I have washed the car several times, and driven it in the rain several times since and have had no further issues. I have checked for water many times since then and have not found any further evidence of water coming in.

Just thought this post might help some if they too are experiencing these types of problems.

Hope this helps!
 

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The PCM "Computer" is under the hood. The SJB, smart junction box, is under the dash. Is that what you're talking about??
 

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Did you take any pics to help folks out who may encounter this issue? :)
 
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