DTC 37

Trouble Code 37, Left Side Oxygen Sensor Diagnosis:

Trouble Code 37, Left Side Oxygen Sensor Circuit Diagram:

DIAGNOSTIC CHART AND DIAGRAM

1. CHECK INPUT SIGNAL FOR ECU
1) Connect voltmeter between terminal #5 of the ECU B59 connector and ground.
2) Start engine and idle.
3) Observe voltmeter.

Connector & Terminal/Specified value
(B61) No. 5 - Body/0.1 - 1.0 V

Oxygen Sensor Connector Identification:

2. CHECK OXYGEN SENSOR
1) With engine idling, disconnect oxygen sensor electrical connector.
2) Measure voltage between body ground and oxygen sensor connector terminal #4 (sensor side).

Terminal/Specified value
No. 4 - Body/0.1 - 1.0 V

3. CHECK HARNESS CONNECTOR BETWEEN ECU AND OXYGEN SENSOR
1) Turn ignition OFF.
2) Disconnect ECU and oxygen sensor electrical connectors.
3) Check resistance of wire between ECU connector B59 terminal #5 and terminal #4 of the oxygen sensor connector.

Connector & Terminal/Specified value
(B61) No. 5 - (B16) No. 4/0 ohms

4) Leaving one probe still connected to the oxygen sensor connector terminal #4, connect other probe to body ground.
5) Observe ohm reading.

Connector & Terminal/Specified value
(B16) No. 4 - Body/1 M ohm, min.

4. CHECK HARNESS CONNECTOR BETWEEN OXYGEN SENSOR AND MAIN RELAY
1) Disconnect main relay connector under drivers side of the dash board.
2) Check resistance between oxygen sensor terminals and main relay terminals.

Connector & Terminal/Specified value
(B16) No. 1 - (B52) No. 2/0 ohms
(B16) No. 2 - (B52) No. 4/0 ohms

5. CHECK POWER SUPPLY CIRCUIT OF MAIN RELAY
1) Turn ignition switch ON.
2) Measure voltage between main relay harness terminals #2 and #4 and body ground.

Connector & Terminal/Specified value
(B52) No. 2 - Body/10 V, min.
(B52) No. 4 - Body/10 V, min.