Test No. 47: Only One Horn Operates

NOTE: Three different horns are used. One theft-deterrent horn is located on passenger's strut tower in engine compartment. Two standard horns are mounted at each side of vehicle, just behind the front bumper. Theft-deterrent horn is entirely controlled by theft-deterrent Electronic Control Unit (ECU). Standard horns are controlled either by pushing horn switch or by body ECU when theft-deterrent system has been activated. For testing procedures covering theft-deterrent horn and theft-deterrent system, see ANTI-THEFT SYSTEMS - AVALON article.

Remove the inoperative horn. Horns are mounted at each side of the vehicle, just behind the front bumper. Using jumper wires, connect battery voltage and ground at electrical terminals on the horn and check horn operation. If horn operates, go to next step. If horn does not operate, replace horn and check horn operation.
Check wiring harness and electrical connectors between the horns. See WIRING DIAGRAMS in STEERING COLUMN SWITCHES - CARS article. Repair wiring harness or electrical connectors as necessary and recheck horn operation.