Toyota Tundra Service Manual: A/f Sensor Heater Relay

On-vehicle Inspection

ON-VEHICLE INSPECTION

PROCEDURE

1. REMOVE INTEGRATION RELAY

2. INSPECT INTEGRATION RELAY (A/F)

NOTICE:

Some relays are built into the integration relay. The integration relay cannot be disassembled. If there is a malfunction in the circuit of the integration relay, replace the integration relay.
The internal circuit of the integration relay is as shown in the illustration below. Inspect the integration relay using the following procedures.

(a) Measure the resistance of the A/F fuse.

(1) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
A/F fuse	Always	Below 1 Ω

If the result is not as specified, replace the A/F fuse.

(b) Measure the resistance of the A/F sensor heater relay.

(1) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
1C-1 - 1A-4	When battery voltage is not applied to terminals 1A-2 and 1A-3	10 kΩ or higher
1C-1 - 1A-4	When battery voltage is applied to terminals 1A-2 and 1A-3	Below 1 Ω

If the result is not as specified, replace the integration relay.

3. INSTALL INTEGRATION RELAY

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Toyota Tundra Owners Manual