Hydraulic Unit Check: Notes

Required Special Tools: 

• MB991958: scan tool Sub Assembly
  • MB991824: Vehicle Communication Interface (V.C.I.)
  • MB991827: scan tool USB Cable
  • MB991910: scan tool Main Harness A (Vehicles with CAN communication system)

1. Raise the vehicle using a jack and support the specified points with a rigid rack.
   CAUTION: Before connecting or disconnecting scan tool, always turn the ignition switch to the LOCK (OFF) position.
2. Before setting scan tool, 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 scan tool while depressing the brake pedal. When carrying out the actuator tests No. 05 to 08, perform the actuator tests using scan tool 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 light flashes at a rate of 2 Hz.
   • When ASC-ECU is disabled due to the fail-safe function, the scan tool actuator test cannot be performed.
   • After the actuator test has been performed, the ABS warning light, brake waning light, ASC ON indicator light, and ASC OFF indicator light illuminate until the ignition switch is turned to ON again or the communication between scan tool and ASC-ECU is terminated.
   Fig 1: Timing Chart

   Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
5. This is indicated as shown in the above illustration.
6. When any malfunction has been found, take a necessary action according to the "Judgment Chart."

   Judgment Chart 

   JUDGMENT CHART
   
   

   Display on scan tool	Operation	Test result	Judgment	Cause	Measure
   01 FL wheel ABS 02 FR wheel ABS 03 RL wheel ABS 04 RR wheel ABS	Depress the brake pedal to lock the wheel. Select the vehicle to be inspected using scan tool, 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 FL wheel TCL 06 FR wheel TCL 07 RL wheel TCL 08 RR wheel TCL	Select the vehicle to be inspected using scan tool, 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 scan tool.