Quote:
As I said, null modem connectors loop some of the other connectors back to the empeg side.


I'm confused. He said he's using the sled in the car. When I look at this wiring diagram, it shows that the only things connected to pins 1 and 4 at the empeg side are the phone mute line and the ignition sense.

I could understand how having those two things go high or low could theoretically mess up an external device. But I don't see how a null-modem cable looping anything to either of those pins would mess up serial communication on the empeg?
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Tony Fabris