F 550 4WD Super Duty V10-6.8L VIN S (2000)
Horn Relay: Testing and Inspection
Micro ISO Relay (Half)
Terminals
Use 73 Digital Multimeter to check for continuity between terminal 2 and all other terminals. If the resistance is 5 ohms or less between terminal 2 and
any other terminal, replace the relay. If resistance is greater than 5 ohms, continue the test. Use two jumper wires to connect relay terminal 1 and
terminal 3 directly to the positive battery terminal. Set 73 Digital Multimeter in the volts position and check for voltage at terminal 4. If battery voltage
is not indicated, replace the relay. If battery voltage is indicated, connect a third jumper wire to terminal 2 and ground the jumper wire to a known good
ground. Check for voltage at terminal 5. If battery voltage is not indicated, replace the relay.
