2.With the engine stopped, step on the brake pedal several times.
Then step on the brake pedal and start the engine. If the pedal moves downward slightly, the booster is in good
condition. If there is no change, the booster is inoperative.
3.With the engine running, step on the brake pedal and then stop the engine.
Hold the pedal depressed for 30 seconds. If the pedal height does not change, the booster is in good condition, if
the pedal rises, the booster is inoperative.
If the above three tests are okay, the booster performance can be determined as good.
Even if one of the above three tests is not okay, check the check valve, vacuum hose and booster for malfunction.
VACUUM HOSE (CHECK VALVE)
INSPECTION
1. Disconnect the brake booster vacuum hose (check valve built in) (A) at the booster (B).
2. Start the engine and let it idle. There should be vacuum available. If no vacuum is available, the check valve is not
working properly. Replace the back booster vacuum hose and check valve and retest.
[LHD]
BRAKE SWITCH CLEARANCE
Screw in the brake switch until its plunger is fully depressed (threded end (A) touching the pad (B) on the pedal arm)
then brake off the switch 3/4 turn to make 0.5 ~ 1.0 mm(0.0197 ~ 0.0394 in.) of clearance between the brake switch
connector. Make sure that the brake lights go off when the pedal is released.
PEDAL FREE PLAY
1.With the engine off, inspect the pedal free play (A) on the pedal pad (B) by pushing the pedal by hand.
Free play: 3 ~ 8 mm (0.12 ~ 0.31 in.)
2.If the pedal free play is out of specification, adjust the brake switch (C). If the pedal free play is insufficient, it may
result in brake drag.
INSPECTION OF FRONT DISC BRAKE PAD
1.Check the brake pad thickness through the caliper body inspection hole.
Pad thickness
Standard value : 10.5 mm ( 0.41 in)
Service limit : 2 mm (0.0787 in)
2007 > 2.7L V6 GASOLINE >
DESCRIPTION
This specification applies to HCU(Hydraulic Control Unit) and ECU(Electronic Control Unit) of the HECU.(Hydraulic and
Electronic Control Unit)
This specification is for the wiring design and installation of ABS/TCS/ESC ECU.
This unit has the functions as follows.
a. Input of signal from Pressure sensor, Steering angle sensor, Yaw & Lateral G sensor, the wheel speed sensors
attached to each wheel.
b. Control of braking force / traction force/ yaw moment.
c. Failsafe function.
d. Self diagnosis function.
e. Interface with the external diagnosis tester.
Installation position : engine compartment a. Brake tube length from Master cylinder port to HECU inlet port should be max. 1m
b. The position should not be close to the engine block and not lower than the wheel.
OPERATION
The ECU shall be put into operation by switching on the operating voltage (IGN).
On completion of the initialization phase, the ECU shall be ready for operation.
In the operating condition, the ECU shall be ready, within the specified limits (voltage and temperature), to process the
signals offered by the various sensors and switches in accordance with the control algorithm defined by the software
and to control the hydraulic and electrical actuators.
Wheel Sensor signal processing
The ECU shall receive wheel speed signal from the four active wheel sensors.
The wheel signals are converted to voltage signal by the signal conditioning circuit after receiving current signal from
active wheel sensors and given as input to the MCU.
Solenoid Valve Control
When one side of the valve coil is connected to the positive voltage that is provided through the valve relay and the
other side is connected to the ground by the semiconductor circuit, the solenoid valve goes into operation.
The electrical function of the coils are always monitored by the valve test pulse under normal operation conditions.
Voltage limits
a.Overvoltage
When overvoltage is detected(above 16.8 V), the ECU switches off the valve relay and shuts down the system.
When voltage is returned to operating range, the system goes back to the normal condition after the initialization
phase.
b. Undervoltage
In the event of undervoltage(below 9.3 V), ABS control shall be inhibited and the warning lamp shall be turned on.
When voltage is returned to operating range, the warning lamp is switched off and ECU returns to normal operating
mode.
Pump Motor Checking
The ECU performs a pump motor test at a speed of 15km/h once after IGN is switched on.
Diagnostic Interface
Failures detected by the ECU are encoded on the ECU, stored in a EEPROM and read out by diagnostic equipment
when the ignition switch is turned on.
The diagnosis interface can also be used for testing the ECU during production of the ECU and for actuating the HCU
(Air - bleeding line or Roll and Brake Test line).
Warning Lamp module
2007 > 2.7L V6 GASOLINE >
STANDARD FLOW OF DIAGNOSTIC TROUBLESHOOTING
NOTES WITH REGARD TO DIAGNOSIS
The phenomena listed in the following table are not abnormal.
Phenomenon Explanation
System check sound When starting the engine, a thudding sound can sometimes be heard coming
from inside the engine compartment. This is because the system operation check
is being performed.
ABS operation sound a.Sound of the motor inside the ABS hydraulic unit operation (whine).
b. Sound is generated along with vibration of the brake pedal (scraping).
c. When ABS operates, sound is generated from the vehicle chassis due to
repeated brake application and release
(Thump : suspension; squeak: tires)
ABS operation (Long braking
distance) For road surfaces such as snow- covered and gravel roads, the braking distance
for vehicles with ABS can sometimes be longer than that for other vehicles.
Accordingly, advise the customer to drive safely on such roads by lowering the
vehicle speed.
Diagnosis detection conditions can vary depending on the diagnosis code. When checking the trouble symptom after
the diagnosis code has been erased, ensure that the requirements listed in "Comment" are met.
SCAN TOOL (PRO) CHECK
1. Turn the ignition switch OFF.
2. Connector the Scan tool to the 16P data link connector located the driver's side kick panel.
c.Stop lamp switch circuit.
d. Check the hydraulic circuit for leakage.
Communication with Scan tool is not possible.
(Communication with any system is not possible) a.
Power source circuit
b. Diagnosis line
Communication with Scan tool is not possible.
(Communication with ABS only is not possible) a.
Power source circuit
b. Diagnosis line
c. HECU
When ignition key is turned ON (engine OFF), the ABS
warning lamp does not light up. a.
ABS warning lamp circuit
b. HECU
Even after the engine is started, the ABS warning lamp
remains ON. a.
ABS warning lamp circuit
b. HECU
During ABS operation, the brake pedal may vibrate or may not be able to be depressed. Such phenomena are
due to intermittent changes in hydraulic pressure inside the brake line to prevent the wheels from locking and is
not an abnormality.
DETECTING CONDITION
Trouble Symptoms Possible Cause
Brake operation varies depending on driving conditions and road
surface conditions, so diagnosis can be difficult.However if a normal
DTC is displayed, check the following probable cause. When the
problem is still occurring, replace the ABS control module. a.
Inoperative power source circuit
b. Inoperative wheel speed sensor circuit
c. Inoperative hydraulic circuit for leakage
d. Inoperative HECU
INSPECTION PROCEDURES
DTC INSPECTION
1. Connect the Scan Tool with the data link connector and turn the ignition switch ON.
2. Verify that the system is operating to specifications.
Is the system operating to specifications ?
▶ Check the power source circuit.
▶ Erase the DTC and recheck using Scan Tool.
CHECK THE POWER SOURCE CIRCUIT.
1. Disconnect the connector from the ABS control module.
2. Turn the ignition switch ON, measure the voltage between terminal 18 of the ABS control module harness side
connector and body ground.
Specification: approximately B+
Is the voltage within specification?
▶ Check the ground circuit.
▶ Check the harness or connector between the fuse (10A) in the engine compartment junction block and the ABS
control module. Repair if necessary.
▶ Replace the leaking hydraulic lines.
DETECTING CONDITION
Trouble Symptoms Possible Cause
Possible malfunction in the power supply system (including ground)
for the diagnosis line. a.
An open in the wire
b. Poor ground
c. Inoperative power source circuit
INSPECTION PROCEDURES
CHECK THE POWER SUPPLY CIRCUIT FOR THE DIAGNOSIS
Measure the voltage between terminal 9 of the data link connector and body ground.
Specification: approximately B+
Is voltage within specification?
▶ Check the ground circuit for the diagnosis.
▶ Repair an open in the wire. Check and replace fuse (15A) from the engine compartment junction block.
CHECK THE GROUND CIRCUIT FOR THE DIAGNOSIS
Check for continuity between terminal 5 of the data link connector and body ground.
Is there continuity?
▶ Repair an open in the wire between terminal 5 of the data link connector and ground point.
DETECTING CONDITION
Trouble Symptoms Possible Cause
When communication with Scan Tool is not possible, the cause may
be probably an open in the HECU power circuit or an open in the a.
An open in the wire
be probably an open in the HECU power circuit or an open in the
diagnosis output circuit.b.
Inoperative HECU
c. Inoperative power source circuit
INSPECTION PROCEDURES
CHECK FOR CONTINUITY IN THE DIAGNOSIS LINE
1. Disconnect the connector from the ABS control module.
2. Check for continuity between terminals 11 of the ABS control module connector and 1 of the data link connector.
Is there continuity?
▶ Check the power source of ABS control module.
▶ Repair an open in the wire.
CHECK THE POWER SOURCE OF ABS CONTROL MODULE
1. Disconnect the connector from the ABS control module.
2. Turn the ignition switch ON, measure the voltage between terminal 18 of the ABS control module harness side
connector and body ground.
Specification: approximately B+
Is voltage within specification?
▶ Check for poor ground.
▶ Check the harness or connector between the fuse (10A) in the engine compartment junction block and the ABS
control module.Repair if necessary.
CHECK FOR POOR GROUND
Check for continuity between terminal 5 of the data link connector and ground point.
▶ Replace the ABS control module and recheck.
▶ Repair an open in the wire or poor ground.
DETECTING CONDITIONTrouble Symptoms Possible Cause
When current flows in the HECU the ABS warning lamp turns from
ON to OFF as the initial check.Therefore if the lamp does not light up,
the cause may be an open in the lamp power supply circuit, a blown
bulb, an open in the both circuits between the ABS warning lamp and
the HECU, and the inoperative HECU. a.
Inoperative ABS warning lamp bulb
b. Blown No.2 fuse (10A) in the engine
compartment junction block
c. Inoperative ABS warning lamp module
d. Inoperative HECU
INSPECTION PROCEDURES
PROBLEM VERIFICATION
Disconnect the connector from the ABS control module and turn the ignition switch ON.
Does the ABS warning lamp light up?
▶ It is normal. Recheck the ABS control module.
▶ Check the power source for the ABS warning lamp.
CHECK THE POWER SOURCE FOR THE ABS WARNING LAMP
1. Disconnect the instrument cluster connector and turn the ignition switch ON.
2. Measure the voltage between terminal 8 of the cluster harness side connector and body ground.
Specification: approximately B+
Is voltage within specification?
▶ Repair bulb or instrument cluster assembly.
▶ Check for blown fuse.