Ford Repair Questions? Ask a Mechanic for Answers ASAP
Welcome, I'm Chris (aka Moose), my normal schedule online is around lunch and after dinner till early morning.
The flashing light is the PCM telling you there is a concern with the transmission and codes are stored which a scan tool can retrieve. This is not related to the wire harness for the trailer.
If you know the codes stored or have any symptoms I can help more as to what is wrong and how to address it. One thing to look at is the trans oil temp reading, that is a common failure part in the 5R110.
Please read this:
Thanks for using Just Answer, Chris