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DESCRIPTION
While the ABS is operating, the skid control ECU turns the ABS MTR MAIN relay on
and activates the
pump motor in the brake actuator.
These codes may be stored if the motor relay (BM) voltage becomes lower than a
specified level due to
insufficient output from the battery or alternator.
| DTC Code | Diag Code | DTC Detection Condition | Trouble Area |
| C0273 | 13 |
When either of the
following is detected:
|
• ABS fuse • ABS MTR MAIN relay • ABS MTR MAIN relay circuit • Brake actuator assembly • Skid control ECU |
| C0274 | 14 |
When either of the following is detected:
|
• ABS fuse • ABS MTR MAIN relay • ABS MTR MAIN relay circuit • Brake actuator assembly • Skid control ECU |
WIRING DIAGRAM
INSPECTION PROCEDURE
Detail
- Remove the ABS fuse from the No. 2 relay block.
- Measure the resistance according to the value (s) in the table below.
Standard resistance
Tester Connection Condition Specified Condition ABS (50 A) fuse Always Below 1 Ω
REPLACE ABS FUSE
[2] INSPECT ABS MOTOR RELAY (ABS MTR MAIN)
- Install the ABS fuse.
- Remove the ABS MTR MAIN relay.
- Measure the resistance according to the value (s) in the table below.
Tester Connection:
Tester Connection Condition Specified Condition 3-5 Voltage is not applied between terminals 1 and 2 10 kΩ or higher 3-5 Apply the battery voltage between terminals 1 and 2 Below 1 Ω
REPLACE ABS MOTOR RELAY (ABS MTR MAIN)
[3] INSPECT NO. 2 RELAY BLOCK (POWER SOURCE TERMINAL)
- Measure the voltage according to the value (s) in the table below.
Standard voltage:
Tester Connection Condition Specified Condition ABS MTR MAIN relay terminal 5 - Body ground Always 20 to 32 V
REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)
[4] INSPECT BRAKE ACTUATOR ASSEMBLY
- Disconnect the brake actuator connector.
- Measure the resistance according to the value (s) in the table below.
Standard resistance:
Tester Connection Condition Specified Condition 2 (BM) - 3 (MT) Always 31.3 to 34.7 Ω 3 (MT) - Body ground Always 10 kΩ or higher
REPLACE BRAKE ACTUATOR ASSEMBLY
(See BRAKE ACTUATOR REMOVAL)
[5] CHECK HARNESS AND CONNECTOR (BRAKE ACTUATOR - NO. 2 RELAY BLOCK)
- Measure the resistance according to the value (s) in the table below.
Standard resistance:
Tester Connection Condition Specified Condition S22-2 (BM) - ABS MTR MAIN relay terminal 3 Always Below 1 Ω S22-2 (BM) - Body ground Always 10 kΩ or higher
REPAIR OR REPLACE HARNESS OR CONNECTOR
[6] CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - BRAKE ACTUATOR)
- Disconnect the skid control ECU connector.
- Measure the resistance according to the value (s) in the table below.
Standard resistance:
Tester Connection Condition Specified Condition S14-18 (MT) - S22-3 (MT) Always Below 1 Ω S14-18 (MT) - Body ground Always 10 kΩ or higher
REPAIR OR REPLACE HARNESS OR CONNECTOR
[7] CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - NO. 2 RELAY BLOCK)
- Measure the resistance according to the value (s) in the table below.
Standard resistance:
Tester Connection Condition Specified Condition S14-12 (MR) - ABS MTR MAIN relay terminal 2 Always Below 1 Ω S14-12 (MR) - Body ground Always 10 kΩ or higher S14-1 (R+) - ABS MTR MAIN relay terminal 1 Always Below 1 Ω S14-1 (R+) - Body ground Always 10 kΩ or higher
REPAIR OR REPLACE HARNESS OR CONNECTOR
[8] RECONFIRM DTC
- Clear the DTC (See Pub. No. S1-YXZE05A, page 05- 108).
- Start the engine.
- Drive the vehicle at a speed of 20 km/h (12 mph) or more
for 30 seconds or more.- Check if the same DTC is recorded (See Pub. No. S1-
YXZE05A, page 05-108).
Reinstall the relays, connectors, etc. and restore the vehicle to its prior condition before rechecking for DTCs.
Result:
Result Proceed to DTCs (C0273 and/or C0274) are not output A DTCs (C0273 and/or C0274) are output B
- If a speed signal of 6 km/h (4 mph) or more is input to the skid control ECU, with the ignition switch ON and the stop light switch off, the ECU performs self diagnosis of the motor and solenoid circuits.
- If the normal system code is output (the trouble code is not output), slightly jiggle the connectors, wire harness, and fuses of the skid control ECU and brake actuator assembly. Make sure that no DTCs are output.
- If any DTCs are output while jiggling a connector or wire harness of the skid control ECU and brake actuator assembly, inspect and repair the connector or wire harness.
- It is suspected that the DTCs were output due to a bad connection of the connector terminal.
A
CHECK FOR INTERMITTENT PROBLEMS (SYMPTOM SIMULATION)
(See DIAGNOSIS SYSTEM).B
REPLACE SKID CONTROL ECU.
- Confirm the DTC C0274 is inactive
- Start the engine and let it idling condition.
- Verify the DTC C0274 is inactive.
- DTC Clear
- Clear the DTC with Hino DX
- Confirm the same DTC is not reoccurred
- C0274 is reoccur: Return to first process
- Other DTC appear: Refer to concerned Trouble shooting
Complete
