Still tracing down the problem with the wipers on our 67 Impala. By running grounds to the outer blades on the motor connection, we were able to get the wipers to turn at both speeds. Next we wanted to validate that our dash was grounded. I followed and tested the ground straps to the firewall. Had continuity. Could not really find the other side of that ground bolt under the dash, but went ahead and tested ground continuity to the dash as well as the switch. They both had continuity.
Am I right to assume I need a new switch? And if so, will any GM 2 speed switch for 1967 work?