Component Tests and General Diagnostics

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

Terminals:

Micro ISO Relay
Using the multimeter, check for the 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. Using two jumper wires, connect relay terminals 1 and 3 directly to the positive battery terminal. Using the multimeter set in the 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.