Headlight Relay Circuit

LIGHTING SYSTEM: Headlight Relay Circuit

Headlight Relay Circuit

DESCRIPTION

The multiplex network body ECU controls headlight relay (H-LP R, H-LP L) when signal is received from the headlight dimmer switch assembly.
The headlight relay installed in the power distributor.
1 Description
1 The power distributor installed in the J/B No. 2 uses the no-contact type relay with a semiconductor.
2 The power distributor has a function to protect the power distributor circuit if overcurrent is applied to the power distributor or overheating occurs.
- Malfunction is detected in the wire harness connected to the J/B No. 2.
- Malfunction is detected in the interior relay of the J/B No. 2.

3 The power distributor has a mode monitor terminal for external checking of the operating condition (normal or protect condition) of the power distributor.
4 The operating condition (normal or protect condition) of the semiconductor relay can be checked using the output voltage from the mode monitor terminal.
NOTE: Check that no DTCs are output in the ABS and VSC motor relay.

If any DTC (C0273/13, C0274/14, C1361/91) is detected, inspect the ABS and VSC motor relay in accordance with the troubleshooting of the brake system. Reading and Clearing Diagnostic Trouble Codes
5 When the semiconductor relay is operation normally, the mode monitor terminal outputs approximately 6 V. When the semiconductor relay operates in protect mode, the mode monitor terminal outputs about 0 V. However, the mode monitor terminal outputs for the overall operating condition of the power distributor, so it is not possible to specify the semiconductor relay during protect operation.
6 When the fail-safe function operates, the power distributor performs the following operations:
- Stops the operation of the troubled semiconductor relay only.
- Stops the power supply to the troubled semiconductor relay circuit only.
HINT: Normal semiconductor relay or circuit operates properly.

7 While the fail-safe function operates, check for a short circuit in the following areas:
- Wire harness driven by relay on the terminal side and body ground.
- Inside the power distributor (including the semiconductor relay)

2 Recovery from Fail-Safe
1 The power distributor soon restores the semiconductor relay function, but if a load abnormality still continues, the power distributor again stops the semiconductor relay function. (except Rr-DEF Relay)
2 The power distributor and the semiconductor relay function stop until the rear defogger switch turns on again.
Then the rear defogger switch turns on again, the semiconductor relay function recovers, but if the load abnormality is not corrected by this time, the Power Distributor again stops the semiconductor relay function.
If the load abnormality is corrected, the semiconductor relay function recovers when the rear defogger switch turns on again. (Rr-DEF Relay)

WIRING DIAGRAM





INSPECTION PROCEDURE
HINT: Start the inspection from step 1 when using the intelligent tester, and start from step 2 when not using the intelligent tester.

PROCEDURE

1. PERFORM ACTIVE TEST USING INTELLIGENT TESTER
(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch to ON position and press the intelligent tester main switch ON.
(c) Select the item below in the ACTIVE TEST and then check that the relay operates.

BODY No. 1





NG -- CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)
OK -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
2. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)





(a) Disconnect the connector from the J/B No. 2 (power distributor).
(b) Measure the voltage according to the value(s) in the table below.
Voltage:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
3. CHECK MODE MONITOR TERMINAL (H-LP R RELAY, H-LP L RELAY)
(a) Preparation
(1) Connect the connector.
(2) Remove the cover of the fusible link block assembly.
(3) Set the vehicle to the following condition.

- Ignition switch ON.
- Headlight dimmer switch LO.
- Light control switch ON.
(b) Check voltage





(1) Measure the voltage between the Mode Monitor Terminal and body ground.
RESULT:






B -- CHECK HARNESS AND CONNECTOR (SHORT CIRCUIT DRIVEN SIDE BY RELAY)
A -- Continue to next step.
4. INSPECT JUNCTION BLOCK NO.2 (HEAD LIGHT RELAY)
(a) Turn the ignition switch to OFF position.
(b) Remove the J/B No.2.
(c) Inspect the H-LP R.





(1) Connect the positive battery lead to terminal +B of the J/B No.2 and the negative lead to terminal SGND, PGND.






(2) Measure the voltage according to the value(s) in the table below.
Voltage:






(3) Connect the battery negative lead to terminal HRLY of the J/B No.2.






(4) Measure the voltage according to the value(s) in the table below.
Voltage:





(d) Inspect the H-LP L.
(1) Connect the positive battery lead to terminal +B of the J/B No.2 and the negative lead to terminal SGND, PGND.






(2) Measure the voltage according to the value(s) in the table below.
Voltage:






(3) Connect the battery negative lead to terminal HRLY of the J/B No.2.






(4) Measure the voltage according to the value(s) in the table below.
Voltage:






NG -- REPLACE JUNCTION BLOCK NO.2
OK -- Continue to next step.
5. CHECK HARNESS AND CONNECTOR (HRLY SIGNAL CIRCUIT)
(a) Disconnect the connector from the instrument panel J/B.





HINT: Reconnect the J/B No. 2 connector.
(b) Measure the voltage according to the value(s) in the table below.
Voltage:






NG -- CHECK HARNESS AND CONNECTOR (J/B NO. 2 - INSTRUMENT PANEL J/B)
OK -- Continue to next step.
6. CHECK HARNESS AND CONNECTOR (J/B NO. 2 - BULB)





(a) Disconnect the connector from the J/B No. 2 (power distributor).





(b) Disconnect the connectors from the headlight bulbs.
(c) Measure the resistance according to the value(s) in the table below.
Resistance:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
7. CHECK HARNESS AND CONNECTOR (BULB - BODY GROUND)





(a) Measure the resistance according to the value(s) in the table below.
Resistance:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
8. CHECK HARNESS AND CONNECTOR (J/B NO. 2 - INSTRUMENT PANEL J/B)





(a) Disconnect the connectors from the J/B No. 2 (power distributor) and instrument panel J/B.
(b) Measure the resistance according to the value(s) in the table below.
Resistance:










NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
9. CHECK HARNESS AND CONNECTOR (SHORT CIRCUIT DRIVEN SIDE BY RELAY)
(a) Preparation
(1) For easier disconnection remove the J/B No.2 and then take apart the connectors.





(2) Disconnect only the connector "2A".
(b) Check voltage
(1) Measure the voltage between the Mode Monitor Terminal and body ground.
RESULT:






B -- REPLACE JUNCTION BLOCK NO.2
A -- REPAIR OR REPLACE HARNESS OR CONNECTOR (SHORT CIRCUIT BETWEEN HEADLIGHT LO AND J/B NO.2)