Mirror Defogger Relay Test
Using an ohmmeter, check for continuity between terminals No. 3 and 4. See Fig 1. If continuity does not exist, replace relay. If continuity exists, connect battery voltage to terminals No. 3 and 4, and check for continuity between terminals No. 1 and 2. If continuity exists, relay is okay. If continuity does not exist, replace relay.