HYDRAULIC UNIT (HU) CHECK


1.Raise the vehicle using a jack and support the specified points with a rigid rack.
2.
caution Before connecting or disconnecting M.U.T.-III, always turn the ignition switch to the LOCK (OFF) position.
Before setting M.U.T.-III, turn the ignition key to the LOCK (OFF) position.
3.Confirm that the selector lever is in the "N" position, and then start the engine.
4.When carrying out the actuator tests No. 01 to 04, perform the actuator tests using M.U.T.-III while depressing the brake pedal. When carrying out the actuator tests No.05 to 08, perform the actuator tests using M.U.T.-III without depressing the brake pedal. When carrying out the actuator tests, rotate the wheel by hands to confirm that the braking force changes.
note
  • While performing the actuator test, the ABS warning lamp flashes at a rate of 2 Hz.
  • When ASC-ECU is disabled due to the fail-safe function, the M.U.T.-III actuator test cannot be performed.
  • After the actuator test has been performed, the ABS warning lamp, brake waning lamp, ASC ON indicator lamp, and ASC OFF indicator lamp illuminate until the ignition switch is turned to ON again or the communication between M.U.T.-III and ASC-ECU is terminated.
5.

This is indicated as shown in the above.
6.When any malfunction has been found, take a necessary action according to the "Judgment Table."
Display on M.U.T.-III
 Operation
 Test results
 Judgment
 Cause
 Measures
01 FR wheel ABS
02 FL wheel ABS
03 RR wheel ABS
04 RL wheel ABS
  • Depress the brake pedal to lock the vehicle.
  • Select the vehicle to be inspected using M.U.T.-III, perform the actuator test.
  • Rotate the selected wheel by hands to confirm the braking force.

 Braking force decreases for 3 seconds from the lock status.
 Normal
 -
 -
The wheel does not lock even if the brake pedal is depressed.
 Error
 Clogged brake line other than hydraulic unit
 Check and clean the brake line.
Clogged hydraulic circuit in the hydraulic unit
 Replace the hydraulic unit assembly.
Braking force does not decrease.
 Faulty routing of hydraulic unit brake tube
 Route the brake tube correctly.
Malfunction of hydraulic unit solenoid valve operation
 Replace the hydraulic unit assembly.
05 FR wheel TCL
06 FL wheel TCL
07 RR wheel TCL
08 RL wheel TCL
  • Select the vehicle to be inspected using M.U.T.-III, perform the actuator test.
  • Rotate the selected wheel by hands to confirm the braking force.

 Lock condition occurs for 3 seconds from the status without braking force.
 Normal
 -
 -
The wheel does not lock.
 Error
  • Faulty routing of hydraulic unit brake tube
  • Clogged brake line other than hydraulic unit

 Check and clean the brake line.
Clogged hydraulic circuit in the hydraulic unit
 Replace the hydraulic unit assembly.
7.After the inspection, turn the ignition switch to the LOCK (OFF) position, and then disconnect M.U.T.-III.