DESCRIPTION The main body ECU (multiplex network body ECU) controls the low beam headlights. WIRING DIAGRAM
 CAUTION / NOTICE / HINT
NOTICE:
- Inspect the fuses for circuits related to this system before performing the following procedure.
- Before replacing the main body ECU (multiplex network body ECU), refer to Registration.
Click here 
PROCEDURE |
1. | PERFORM ACTIVE TEST USING TECHSTREAM |
(a) Connect the Techstream to the DLC3. (b) Turn the engine switch on (IG).
(c) Turn the Techstream on. (d) Enter the following menus: Body Electrical / Main Body / Active Test.
(e) Perform the Active Test according to the display on the Techstream. Body Electrical > Main Body > Active Test
|
Tester Display | Measurement Item |
Control Range | Diagnostic Note | |
Headlight Relay | Low beam headlights |
OFF or ON | - | Body Electrical > Main Body > Active Test
|
Tester Display | | Headlight Relay |
OK: Low beam headlights illuminate.
|
Result | Proceed to | |
OK | A | |
NG (for LH Side) | B | |
NG (for RH Side) | C |
| A |
 | PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE |
| C |
| GO TO STEP 9 |
|
B |
 | |
| 2. |
INSPECT HEADLIGHT ASSEMBLY LH (LO TERMINAL VOLTAGE) |
|
*a | Front view of wire harness connector
(to Headlight Assembly LH) | (a) Disconnect the A45 headlight assembly LH connector.
(b) Measure the voltage according to the value(s) in the table below. Standard Voltage: |
Tester Connection | Condition |
Specified Condition | |
A45-4 (LO) - Body ground |
Light control switch in head position |
11 to 14 V |
| NG |
| GO TO STEP 4 |
|
OK | |
| |
| 3. |
CHECK HARNESS AND CONNECTOR (HEADLIGHT ASSEMBLY LH - BODY GROUND) |
(a) Measure the resistance according to the value(s) in the table below.
Standard Resistance: |
Tester Connection | Condition |
Specified Condition | |
A45-7 (E) - Body ground |
Always | Below 1 Ω |
| OK |
| REPLACE HEADLIGHT ASSEMBLY LH |
| NG |
| REPAIR OR REPLACE HARNESS OR CONNECTOR |
| 4. |
CHECK HARNESS AND CONNECTOR (H-LP LH RELAY - HEADLIGHT ASSEMBLY LH) |
(a) Remove the H-LP LH relay. (b) Measure the resistance according to the value(s) in the table below.
Standard Resistance: |
Tester Connection | Condition |
Specified Condition | |
5 (H-LP LH relay) - A45-4 (LO) |
Always | Below 1 Ω | |
5 (H-LP LH relay) or A45-4 (LO) - Body ground |
Always | 10 kΩ or higher |
| NG |
| REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
OK | |
| |
(a) Inspect the H-LP LH relay.
Click here
| NG |
| REPLACE H-LP LH RELAY |
|
OK | |
| |
| 6. |
CHECK HARNESS AND CONNECTOR (POWER SOURCE - H-LP LH RELAY) |
(a) Measure the voltage according to the value(s) in the table below. Standard Voltage: |
Tester Connection | Condition |
Specified Condition | |
1 (H-LP LH relay) - Body ground |
Always | 11 to 14 V | |
3 (H-LP LH relay) - Body ground |
Always | 11 to 14 V |
| NG |
| REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
OK | |
| |
| 7. |
CHECK HARNESS AND CONNECTOR (H-LP LH RELAY - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY) |
(a) Disconnect the 4F instrument panel junction block assembly connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance: |
Tester Connection | Condition |
Specified Condition | |
2 (H-LP LH relay) - 4F-31 |
Always | Below 1 Ω | |
2 (H-LP LH relay) or 4F-31 - Body ground |
Always | 10 kΩ or higher |
| NG |
| REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
OK | |
| |
| 8. |
INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY |
|
*a | Component without harness connected
(Instrument Panel Junction Block Assembly) |
- | - |
(a) Remove the main body ECU (multiplex network body ECU) from the instrument panel junction block assembly.
Click here (b) Measure the resistance according to the value(s) in the table below.
Standard Resistance: |
Tester Connection | Condition |
Specified Condition | |
4F-31 - MB-15 (HRLY) |
Always | Below 1 Ω |
| OK |
| REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) |
| NG |
| REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY |
| 9. |
INSPECT HEADLIGHT ASSEMBLY RH (LO TERMINAL VOLTAGE) |
|
*a | Front view of wire harness connector
(to Headlight Assembly RH) | (a) Disconnect the A44 headlight assembly RH connector.
(b) Measure the voltage according to the value(s) in the table below. Standard Voltage: |
Tester Connection | Condition |
Specified Condition | |
A44-4 (LO) - Body ground |
Light control switch in head position |
11 to 14 V |
| NG |
| GO TO STEP 11 |
|
OK | |
| |
| 10. |
CHECK HARNESS AND CONNECTOR (HEADLIGHT ASSEMBLY RH - BODY GROUND) |
(a) Measure the resistance according to the value(s) in the table below.
Standard Resistance: |
Tester Connection | Condition |
Specified Condition | |
A44-7 (E) - Body ground |
Always | Below 1 Ω |
| OK |
| REPLACE HEADLIGHT ASSEMBLY RH |
| NG |
| REPAIR OR REPLACE HARNESS OR CONNECTOR |
| 11. |
CHECK HARNESS AND CONNECTOR (H-LP RH RELAY - HEADLIGHT ASSEMBLY RH) |
(a) Remove the H-LP RH relay. (b) Measure the resistance according to the value(s) in the table below.
Standard Resistance: |
Tester Connection | Condition |
Specified Condition | |
5 (H-LP RH relay) - A44-4 (LO) |
Always | Below 1 Ω | |
5 (H-LP RH relay) or A44-4 (LO) - Body ground |
Always | 10 kΩ or higher |
| NG |
| REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
OK | |
| |
| 12. |
INSPECT H-LP RH RELAY | (a) Inspect the H-LP RH relay.
Click here
| NG |
| REPLACE H-LP RH RELAY |
|
OK | |
| |
| 13. |
CHECK HARNESS AND CONNECTOR (POWER SOURCE - H-LP RH RELAY) |
(a) Measure the voltage according to the value(s) in the table below. Standard Voltage: |
Tester Connection | Condition |
Specified Condition | |
1 (H-LP RH relay) - Body ground |
Always | 11 to 14 V | |
3 (H-LP RH relay) - Body ground |
Always | 11 to 14 V |
| NG |
| REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
OK | |
| |
| 14. |
CHECK HARNESS AND CONNECTOR (H-LP RH RELAY - MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)) |
(a) Disconnect the G33 main body ECU (multiplex network body ECU) connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance: |
Tester Connection | Condition |
Specified Condition | |
2 (H-LP RH relay) - G33-12 (HRY2) |
Always | Below 1 Ω | |
2 (H-LP RH relay) or G33-12 (HRY2) - Body ground |
Always | 10 kΩ or higher |
| OK |
| REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) |
| NG |
| REPAIR OR REPLACE HARNESS OR CONNECTOR | | 
