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this looks like engine oil to me. the only way oil to get there is leak from engine valve cover gasket and creping or dripping down. Have you tried using a mirror and a flash light for locating a leak from top, which can be dripping on the connector and entering connector?
Access ECM located behind Glove compartment. Remove computer from vehicle and remove screws to open computer box. you can examine for presence of oil. examine connector E5 first while disconnecting it for presence of oil. This is same connector which is used for transmission connection.
If ECU is full of oil but it is working fine, then there is no need to replace it. you can spray wash circuit board with brake cleaner and blow dry with compressed air. wiring you will have to replace and Solenoid wiring connector.
Here I am sending you connector view. Tranny oil pan has to be removed for this operation. I suggest you replace tranny filter at same time, if you end up doing the work.
after oil pan is installed, you need 2.0L of tranny fluid to top up transmission oil. use ATF Type T-IV fluid
I have sent you a picture of oil pan connector.
please click H E R E to see oil pan removal procedures and wiring colors.
Thank you for the accept and Good rating!
Just wanted to post an update:
I think I have a solution to the A/F sensors failing. I am now pretty confident that the problem was transmission fluid wicking through the wiring harness from the transmission sensor to A/F sensors (including between connectors in the ECM behind the glove box). I replaced the failed A/F sensors with new sensors, but before I installed them I spliced in a piece of solid wire in each of the four conductors. The theory was that this would block the transmission fluid that was wicking through the braided wire. I did this about 1.5 years ago and have not had a problem since. Prior to this fix, the A/F sensors were failing in just a few weeks after installing. I also preformed this fix to one of the downstream O2 sensors that failed. I used high quality sealed but splices to splice in the solid wire segments (http://www.mcmaster.com/#9895k11/=tbr293).