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

CIRCUIT OPENING RELAY

1. On Camry, Celica Corolla RWD and Van models, remove glove box. On Pickup and 4Runner models, remove right kick panel, glove box and speaker. On MR2 models, remove rear luggage compartment trim. On Cressida and 1985---Early 1986 Supra models, remove left kick panel. On Corolla FWD models, remove ECU cover from behind center console. On late 1986---1988 Supra models, remove right side kick panel.
2. Remove circuit opening relay with wiring from bracket.
3. Insert voltmeter positive probe into rear of connector at Fp terminal.
4. Meter should read battery voltage during cranking and while engine is running.
5. Disconnect electrical connector from relay and measure resistance between terminals.
6. If relay fails to perform satisfactory, relay is defective.

Fig. 71 Main relay testing:

Fig. 72 Main relay testing:

MAIN RELAY

1985-88

Two main relays are used on 1985 Celica and 1985---Early 1986 Supra models.
1. Turn ignition On while listening to main relay(s). Relay(s) should click when ignition is turned On.
2. Disconnect electrical connector from relay(s) and check resistance between terminals, Figs. 71 and 72.
3. On 22R-E, 22R-TE and 5M-GE engines, meter should read 40---60 ohms between terminals 1 and 2 and infinity between terminals 3 and 4 on No. 1 relay. On 1985 Celica and 1985---Early 1986 Supra models (with No. 2 main relay), meter should read 60---120 ohms between terminals 1 and 2 and infinity between terminals 3 and 4 on No. 2 relay.
4. On all except 22R-E, 22R-TE and 5M-GE engines, ensure continuity exists between terminals 1 and 3 with a resistance value of approximately 50 ohms. Ensure no continuity exists between terminals 2 and 4. Apply battery voltage across terminals 1 and 3, and check for continuity across terminals 2 and 4. Continuity should exist.
5. If relay does not perform as specified, replace.