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 skid control ECU continues. |
|
Tech Tips
This diagnosis procedure is for when DTC U0129 is output by the power management control ECU (GTS display: PM2 Gateway).
WIRING DIAGRAM
CAUTION / NOTICE / HINT
Note
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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, 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.
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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.
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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.
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After performing repairs, perform the DTC check procedure and confirm that the DTCs are not output again.
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DTC check procedure: Turn the power switch on (IG), turn the cruise control system on using the cruise control switch (ON/OFF switch), and wait at least 20 seconds.
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After the repair, perform CAN Bus Check and check that all the ECUs and sensors connected to the CAN communication system are displayed Click here.
Tech Tips
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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.
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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
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RECONFIRM DTC OUTPUT
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Reconfirm DTCs.
Tech Tips
If DTC U1002 is output from PM2 Gateway of the power management control ECU, this indicates a sub bus 12 malfunction. Troubleshoot for DTC U1002 and check for malfunctions in sub bus 12.
Result Result Proceed to U1002 is not output from power management control ECU (GTS display: PM2 Gateway) A U1002 is output from power management control ECU (GTS display: PM2 Gateway) B
B 
GO TO DIAGNOSIS PROCEDURE INDICATED BY OUTPUT DTC Click here
A 
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CHECK DTC (BRAKE SYSTEM)
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Connect the GTS to the DLC3.
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Turn the power switch on (IG).
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Turn the GTS on.
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Enter the following menus: Chassis / ABS/VSC/TRC / Trouble Codes.
OK DTC C1241 is not output.
NG
GO TO DIAGNOSIS PROCEDURE INDICATED BY OUTPUT DTC Click here
OK
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CHECK FOR OPEN IN CAN BUS LINES (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY BRANCH LINE)
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Disconnect the cable from the negative (-) auxiliary battery terminal.
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Text in Illustration *a Front view of wire harness connector
(to Brake Booster with Master Cylinder Assembly)
Disconnect the brake booster with master cylinder assembly (skid control ECU) connector.
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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 Click here
C
REPAIR OR REPLACE CAN BRANCH LINE OR CONNECTOR (SKID CONTROL ECU)
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