F 250 4WD Pickup V6-4.2L VIN 2 (1998)
Four Wheel Drive Selector Relay: Testing and Inspection
RELAY
Testing an ISO relay can be accomplished through the use of three No. 10 (or larger gauge) jumper wires and 73 Digital Multimeter.
Use 73 Digital Multimeter to check for continuity between terminal 2 and all other terminals. If resistance is 5 ohms or less between terminal 2 and
any other terminal, replace the relay. If resistance is greater than 5 ohms, continue with the test. Use two jumper wires to connect relay terminals 1 and
3 directly to the positive battery terminal. With 73 Digital Multimeter set in volts position, 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.
