DESCRIPTION
WIRING DIAGRAM
INSPECTION PROCEDURE
PRECAUTION
DISCONNECT CABLE FROM NEGATIVE BATTERY TERMINAL
CHECK FOR OPEN IN CAN BUS WIRE (SKID CONTROL ECU CAN BRANCH WIRE)
CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - BATTERY AND BODY GROUND)
DTC U0129 Lost Communication with Brake System Control Module
DESCRIPTION
| DTC Code | DTC Detection Condition | Trouble Area |
| U0129 | There is no communication from the master cylinder solenoid (skid control ECU). | Power source circuit of master cylinder solenoid (skid control ECU)
Master cylinder solenoid (skid control ECU) CAN branch wire or connector
Master cylinder solenoid (skid control ECU)
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WIRING DIAGRAM
INSPECTION PROCEDURE
- Inspect the fuses for circuits related to this system before performing the following inspection procedure.
- Operating the ignition switch, any switches or any doors triggers related ECU and sensor communication with the CAN, which causes resistance variation.
- After turning the ignition switch off, waiting time may be required before disconnecting the cable from the battery terminal. Therefore, make sure to read the disconnecting the cable from the battery terminal notice before proceeding with work ().
| 2.DISCONNECT CABLE FROM NEGATIVE BATTERY TERMINAL |
Disconnect the cable from the negative (-) battery terminal before measuring the resistances of the CAN main wire and the CAN branch wire.
- For vehicles with an SRS system:
- Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.
- When disconnecting the cable, some systems need to be initialized after the cable is reconnected ().
| 3.CHECK FOR OPEN IN CAN BUS WIRE (SKID CONTROL ECU CAN BRANCH WIRE) |
Disconnect the A24 master cylinder solenoid (skid control ECU) connector.
Measure the resistance according to the value(s) in the table below.
- Standard Resistance:
| Tester Connection | Switch Condition | Specified Condition |
| A24-11 (CANH) - A24-25 (CANL) | Ignition switch off | 54 to 69 Ω |
Text in Illustration| *a | Front view of wire harness connector
(to Master Cylinder Solenoid [Skid Control ECU]) |
| | REPAIR OR REPLACE SKID CONTROL ECU CAN BRANCH WIRE OR CONNECTOR (CANH, CANL) |
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| 4.CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - BATTERY AND BODY GROUND) |
Connect the cable to the negative (-) battery terminal.
- When disconnecting the cable, some systems need to be initialized after the cable is reconnected ().
Disconnect the A25 master cylinder solenoid (skid control ECU) connector.
Measure the voltage according to the value(s) in the table below.
- Standard Voltage:
| Tester Connection | Switch Condition | Specified Condition |
| A24-2 (+BM1) - Body ground | Always | 11 to 14 V |
| A24-31 (+BS) - Body ground | Always | 11 to 14 V |
| A25-2 (+BM2) - Body ground | Always | 11 to 14 V |
| A24-46 (IG1) - Body ground | Ignition switch ON | 11 to 14 V |
| A25-1 (IG2) - Body ground | Ignition switch ON | 11 to 14 V |
Measure the resistance according to the value(s) in the table below.
- Standard Resistance:
| Tester Connection | Condition | Specified Condition |
| A24-1 (GND1) - Body ground | Always | Below 1 Ω |
| A24-32 (GND2) - Body ground | Always | Below 1 Ω |
| A25-4 (GND3) - Body ground | Always | Below 1 Ω |
Text in Illustration| *a | Front view of wire harness connector
(to Master Cylinder Solenoid [Skid Control ECU]) |
| | REPAIR OR REPLACE HARNESS OR CONNECTOR |
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| OK | |
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| REPLACE MASTER CYLINDER SOLENOID (SKID CONTROL ECU) ()
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