Component Tests and General Diagnostics

Use three No. 10 (or larger gauge) jumper wires, and 73 Digital Multimeter to test an ISO relay. Remove (unplug) the relay to be tested from the engine compartment fuse junction panel, I/P fuse junction panel or individual connector.





Use 73 Digital Multimeter to check for the continuity between terminal 85 and all other terminals. If resistance is 5 ohms or less between terminal 85 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 86 and 30 directly to the positive battery terminal. With 73 Digital Multimeter set in the volts position, check for voltage at terminal 87A. If battery voltage is not indicated, replace the relay. If battery voltage is indicated, connect a third jumper wire to terminal 85 and ground the jumper wire to a known good ground. Check for voltage at terminal 87. If battery voltage is not indicated, replace the relay.