it. That will bypass all fuses and switches. If it blows than the problem is not the horn. On my 92 na the horn is on the drivers side at the front air dam. To do test probably easier to remove horn andf apply 12v+ to connector while the body is negative or grounded.
For the 3rd brake light since you say they all do not work but the Iassume the lower brake lights do work I suspect a connector issue or bad ground. Need to open up the lid panal and check the connector and ground.
