Component Tests and General Diagnostics

Special Service Tool(s):

Special Tool(s)

Testing of an ISO relay can be accomplished through the use of three No. 10 (or larger gauge) jumper wires and a 73 Digital Multimeter. Remove (unplug) the relay to be tested from the power distribution box or individual connector.







Mini ISO Relay
Using the multimeter, check for the continuity between Terminal 85 and all other terminals. If the resistance is 5 ohms or less between Terminal 85 and any other terminal, replace the relay. If the resistance is greater than 5 ohms, continue with the test. Using two jumper wires, connect relay Terminals 86 and 30 directly to the positive battery terminal. Using the 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.







Micro ISO Relay
Using the multimeter, check for the 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 the 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.