[patrickt]

Maybe. With the two fast blow fuses removed attach two 12v test lamps, not a VOM, to the trailer relay side of the removed fuses and to a nice ground. Then repeat the test. If everything is working normally, when the key is on and the turn signal is on, the front lights will flash and the appropriate 12v test lamp will flash there in the driver's seat. With the parking lights on, the back tail lights in the car will be lit, the front parking lights will be lit, and all will remain lit when the turn signal is turned on, but only the 12v test lamps will blink along with the front turn signal light, the rear turn signal lights will not blink.

Just to double check, you do have those four temporary ground wires running to the four corners of the car, right?