Horn Relay

Remove horn relay. Check continuity between horn relay terminals "A" and "C". See Fig 1. If continuity exists, replace horn relay. If continuity does not exist, apply battery voltage and ground across horn relay terminals "B" and "D". Check continuity between horn relay terminals "A" and "C". If continuity exists, horn relay is okay. If continuity does not exist, replace horn relay.

Fig 1: Identifying Horn Relay Terminals

Courtesy of MAZDA MOTORS CORP.