DTC U0129 (PGM-FI System (1.5 L Engine))

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DTC U0129: F-CAN Malfunction (Powertrain Control Module (PCM)-Electric Brake Booster)

General Description

Without ACC

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With ACC

Courtesy of HONDA, U.S.A., INC.

The controller area network (CAN) transmits/receives pulsing signals to/from the control modules simultaneously by using two signal lines (H line and L line). When the information is not sent from the electric brake booster via the F-CAN lines and this condition continues for a specified time or when the information sent from the electric brake booster is abnormal and this condition continues for a specified cycle, the powertrain control module (PCM) detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type

Execution	Continuous
Sequence	None
Duration	1.5 seconds or more

DTC Type

One drive cycle, MIL off

Enable Conditions

Condition	Minimum	Maximum
Elapsed time after the vehicle condition is turned to the ON mode	3 seconds	-
12 volt battery voltage [BATTERY]	10.0 V	-

[ ]: HDS Parameter

Malfunction Threshold

The PCM does not receive any signals via the F-CAN lines for at least 1.5 seconds.
The information sent from the electric brake booster is abnormal at least 20 times.

Possible Cause

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.

F-CAN circuit F-CAN A H line open
F-CAN circuit F-CAN A L line open
F-CAN circuit F-CAN A H line short to ground
F-CAN circuit F-CAN A L line short to ground
F-CAN circuit F-CAN B H line open
F-CAN circuit F-CAN B L line open
F-CAN circuit F-CAN B H line short to ground
F-CAN circuit F-CAN B L line short to ground
Electric brake booster failure
PCM internal circuit failure

Diagnosis Details

Conditions for setting the DTC

When a malfunction is detected, a Pending DTC, a Confirmed DTC, and the freeze data are stored in the PCM memory. The MIL does not come on.

Conditions for clearing the DTC

The Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the 12 volt battery.