C1251 Open in Pump Motor Circuit

1. Turn the ignition switch off.
2. Disconnect the brake actuator connector.
3. Measure the resistance according to the value (s) in the table below.
   
   
   
   Standard resistance: 　

   Tester Connection	Condition	Specified Condition
   S22-1 (GND) - Body ground	Always	Below 1 Ω

REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT)

[2] INSPECT BRAKE ACTUATOR ASSEMBLY

1. Disconnect the brake actuator connector.
2. 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)

[3] RECONFIRM DTC

1. Turn the ignition switch off.
2. Reconnect the brake actuator connector.
3. Clear the DTC (See Pub. No. S1-YXZE05A, page 05-108).
4. Start the engine.
5. Drive the vehicle at a speed of 20 km/h (12 mph) or more for 30 seconds or more.
6. Check if the same DTC is recorded (See Pub. No. S1-YXZE05A, page 05-108).
   
   Result: 　

   Result	Proceed to
   DTC (C1251) is not output	A
   DTC (C1251) is 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 PROBLEM SYMPTOMS TABLE)

B REPLACE SKID CONTROL ECU

1. Confirm the DTC C1251 is inactive

   • Start the engine and let it idling condition.
   • Verify the DTC C1251 is inactive.

   

2. DTC Clear

   • Clear the DTC with Hino DX
   • Confirm the same DTC is not reoccurred

   

C1251 is reoccur: Return to first process Other DTC appear: Refer to concerned Trouble shooting

Complete