DTC C0278: Open in ABS Solenoid Relay Circuit; DTC C0279: Short in ABS Solenoid Relay Circuit: Procedure

1. Remove the ABS NO. 3 fuse from the engine room relay block.
   Fig 1: Identifying ABS No. 3 Fuse

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2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   ABS NO. 3 (30 A) fuse	Always	Below 1 Ω

NG → REPLACE ABS NO. 3 FUSE 

OK: Go to next step 

1. Install the ABS NO. 3 fuse.
   Fig 2: Identifying Skid Control ECU Connector Terminals

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2. Make sure that there is no looseness at the locking part and the connecting part of the connector.
3. Disconnect the skid control ECU connector.
4. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   A66-12 (+BS) - Body ground	Always	11 to 14 V

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (+BS CIRCUIT) 

OK: Go to next step 

1. Measure the resistance according to the value(s) in the table below.
   Fig 3: Identifying Skid Control ECU Connector Terminals (GND1)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A66-1 (GND1) - Body ground	Always	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (GND1 CIRCUIT) 

OK: Go to next step 

HINT: 

This code is detected when a problem is identified in the brake actuator assembly.

The solenoid circuit is in the brake actuator assembly.

Therefore, solenoid circuit inspection and solenoid unit inspection cannot be performed. Be sure to check if the DTC is output before replacing the brake actuator assembly.

1. Reconnect the skid control ECU connector.
2. Clear the DTCs. Refer to DTC CHECK / CLEAR .
3. Start the engine.
4. Drive the vehicle at a speed of 20 km/h (12 mph) or more for 30 seconds or more.
5. Check if the same DTC is recorded. Refer to DTC CHECK / CLEAR .

   Result

   Result	Proceed to
   DTCs (C0278 and C0279) are not output	A
   DTCs (C0278 and/or C0279) are output	B

   HINT: 

   • 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 (no trouble codes are output), slightly jiggle the connectors, wire harnesses, and fuses of the brake actuator assembly. Make sure that no DTCs are output.
   • If any DTCs are output while jiggling a connector or wire harness of the brake actuator assembly (skid control ECU), 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.

B → See step   6 

A → See step   5