Main Relay (Computer/Fuel System): Testing and Inspection

Relay Terminal Identification:

The following is a list of the terminal numbers and what they are commonly connected to:

Terminal No. Description

30 Has battery voltage supplied to it, and can be switched or have battery voltage at all times.
87A Connected to terminal 30 in the de-energized position.
87 Connected to terminal 30 in the energized position, this supplies voltage to the operated device.
86 Connected to the electromagnet and usually connected to a switched power source.
85 Connected to the electromagnet and grounded by the ECU or a switch.

1. A relay in the de-energized position should have continuity between terminals 30 and 87A.
2. With an ohmmeter, measure the resistance between terminals 85 and 86. The ohmmeter should indicate a resistance value of 75 +/- 5 ohms for resistor relays, and 86 +/- 5 ohms for diode relays.

NOTE: Not all relays have battery voltage applied to terminal 30, some have voltage applied to terminals 87 or 87A.