CAN COMMUNICATION SYSTEM(w/o Central Gateway ECU), Diagnostic DTC:U0129
| DTC Code | DTC Name |
|---|---|
| U0129 | Lost Communication with Brake System Control Module |
DESCRIPTION
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| U0129 | No communication from the brake booster with master cylinder assembly (skid control ECU) continues. |
|
Tech Tips
This diagnostic procedure is for when DTC U0129 is output only by the hybrid vehicle control ECU (GTS display: Hybrid Control).
WIRING DIAGRAM
CAUTION / NOTICE / HINT
Note
-
Before measuring the resistance of the CAN bus, turn the power switch off and leave the vehicle for 1 minute or more without operating the key or any switches, or opening or closing the doors. After that, disconnect the cable from the negative (-) auxiliary battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.
-
After turning the power switch off, waiting time may be required before disconnecting the cable from the negative (-) auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) auxiliary battery terminal notices before proceeding with work Click here.
-
Because the order of diagnosis is important to allow correct diagnosis, make sure to begin troubleshooting using How to Proceed with Troubleshooting when CAN communication system related DTCs are output Click here.
-
After the repair, perform the CAN bus check and check that all the ECUs and sensors connected to the CAN communication system are displayed Click here.
-
Inspect the fuses for circuits related to this system before performing the following procedure.
Tech Tips
-
Operating the power switch, any other switches or a door triggers related ECU and sensor communication on the CAN. This communication will cause the resistance value to change.
-
Even after DTCs are cleared, if a DTC is stored again after driving the vehicle for a while, the malfunction may be occurring due to vibration of the vehicle. In such a case, wiggling the ECUs or wire harness while performing the inspection below may help determine the cause of the malfunction.
PROCEDURE
-
RECONFIRM DTC OUTPUT
-
Reconfirm DTCs.
Tech Tips
If the hybrid vehicle control ECU outputs DTC U0100 and DTC U0129, check the branch circuit of sub bus 15.
Result Result Proceed to The hybrid vehicle control ECU outputs only DTC U0129.
(GTS display: Hybrid Control)
A The hybrid vehicle control ECU outputs DTC U0100 and U0129.
(GTS display: Hybrid Control)
B
B 
GO TO DIAGNOSIS PROCEDURE INDICATED BY OUTPUT DTC Click here
A 
-
-
CHECK DTC (BRAKE SYSTEM)
-
Connect the GTS to the DLC3.
-
Turn the power switch on (IG).
-
Turn the GTS on.
-
Enter the following menus: Chassis / ABS/VSC/TRC / Trouble Codes.
Result Result Proceed to DTC C1241 is not output. A DTC C1241 is output. B
B
GO TO DIAGNOSIS PROCEDURE INDICATED BY OUTPUT DTC Click here
A
-
-
CHECK FOR OPEN IN CAN BUS LINES (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (SKID CONTROL ECU) BRANCH LINE)
-
Disconnect the cable from the negative (-) auxiliary battery terminal.
-
Text in Illustration *a Front view of wire harness connector
(to Brake Booster with Master Cylinder Assembly (Skid Control ECU))
Disconnect the A58 brake booster with master cylinder assembly (skid control ECU) connector.
-
Measure the resistance according to the value(s) in the table below.
Standard Resistance Tester Connection Condition Specified Condition A58-35 (CA2H) - A58-34 (CA2L) Cable disconnected from negative (-) auxiliary battery terminal 54 to 69 Ω Result Result Proceed to OK (for LHD) A OK (for RHD) B NG C
A
REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (SKID CONTROL ECU) Click here
B
REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (SKID CONTROL ECU) Click here
C
REPAIR OR REPLACE CAN BRANCH LINES OR CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (SKID CONTROL ECU))
-