Tach jumps with high beams on?

[jlynch1960]

Hi- Strange recent development. When I have the high beams on, the tach jumps up about 2000 rpm and stays there. I disconnected the high beam indicator from the housing and it doesn't happen.

High beam indicator is a single wire (grounded through the housing?) so I don't think it's a gounding issue. If the high beam indicator wire were somehow worn through and making contact with the signal wire from the DME, wouldn't it cause the tach to peg or simply quit, as I understand the signal from the DME is pulsed. Replaced the turn signal relay a couple of months ago so I doubt it could be the cause.

Any help? Would be nice to not blind other drivers with the high beams inadvertently on.