1968 with no power in cab

[Second Series]

Disconnect the battery and ohm it out. Try to probe as far out as possible. You might need to use a length of wire with an alligator clip on the end if your ohm meter leads don’t reach. Connect one end to the + battery cable(battery disconnected) and the other to the horn relay connector red, or whatever is easiest to get to. With the ohm meter connected, start working and flexing the wire harness and bulkhead connector. If there is on open, it may make contact and show on the meter. If you do find the trouble area, move the probes closer until you pin-point the open.