I would like to know how to check the ECM for ground, as I get a message from the code reader something like "unable to communicate with the vehicle." I replaced the ECM with a used one and still get the same message, so I'm wondering if the ground is good, but as the case is all plastic I do not know where the ground runs.
Thanks for any help anyone can offer.

 

I need to know what year your van is. You may need to disconnect all of the other controllers one at a time until you ecu comes back. most of the time its the tcm. The one that is unplug is your probem, also disconnect the cluster as the last resort.

 

What a dope I am.
The Dodge Caravan is a 1992--3.0 liter with 190,000 miles on her. Has run very well all these years and I would like her to set a mileage record.
I thank you for your help!
Troy Benson