F 250 4WD LD Pickup V8-5.4L SOHC VIN L (1997)
Compressor/Pump Relay: Testing and Inspection
DESCRIPTION
Use three No. 10 (or larger gauge) jumper wires, and a 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.
MINI ISO RELAY
Use the 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 that 5 ohms, continue with the test. Use two jumper wires to connect relay terminals 86 and 30
directly to the positive battery terminal. With 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.
