Standard Horn Circuit

Turn ignition off and disconnect ATS ECU connector. Ensure battery voltage exists between ground and ATS ECU connector terminal A24 (Green/Yellow wire). If battery voltage is not present, ensure continuity exists between standard horn relay terminals No. 1 and No. 2. If standard horn relay is okay, repair open or short in harness or connectors between standard horn relay and ATS ECU as necessary. If battery voltage is present, replace ATS ECU and retest system.