GROUP
BRAKES
DATE

Technical Service Bulletin
SUBJECT:

FEBRUARY,
2020

NUMBER
20-BR-001H
MODEL(S)
Ioniq
Electric/Hybrid/Plug-in
(AE EV/HEV/PHEV)
Sonata Hybrid/Plug-in
(LF HEV/PHEV)

SONATA HEV/PHEV AND IONIQ EV/HEV/PHEV
BRAKE BLEEDING PROCEDURE

This bulletin supersedes TSB 18-BR-003 to include noise diagnostic and repair information.
Description: This bulletin describes the procedure to properly bleed the brakes on Sonata
HEV/PHEV (LF) and Ioniq EV/HEV/PHEV (AE) vehicles. This procedure applies when any air is
introduced into the Active Hydraulic Boost (AHB) system, which consists of the pressure supply unit
(PSU), and the integrated brake actuation unit (IBAU). Improper bleeding of the brake system can
result in the presence of air, which may reduce braking effectiveness.

Applicable Vehicles:
 All Sonata Hybrid (LF HEV) and Plug-In Hybrid (LF PHEV) vehicles.
 All Ioniq Hybrid (AE HEV), Plug-In Hybrid (AE PHEV), and Electric (AE EV) vehicles.

Circulate To: General Manager, Service Manager, Parts Manager, Warranty Manager, Service
Advisors, Technicians, Body Shop Manager, Fleet Repair

SUBJECT:

SONATA HEV/ PHEV & IONIQ EV/HEV/PHEV BRAKE BLEEDING

SST Information
Description

Picture

Active Hydraulic Boost
(AHB) Brake Air Bleeding
Tool

Part Number: 09580-3D100

Active Hydraulic Boost
(AHB) Brake Air Bleeding
Tool Adapter

Part Number: 0K585-E8100
NOTE: The special service tools listed above are available for order through Bosch: 1-866-539-4248.
Warranty Information:
Model

Op Code

Operation

Op Time Causal Part # Nature Code Cause Code

BRAKE FLUID
REPLACEMENT OR Refer to
Refer to the 58700A00
AIR BLEEDWEBLTS
Applicable
ADJUSTMENT
for
Vehicles list
current
ADDITIONAL TIME
on page 1
LTS time
58700AH1
FOR HYBRID
BRAKE BLEEDING

58500*

N32

C26

*Refer to the applicable parts catalog for full causal part numbers
TSB #: 20-BR-001H

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SONATA HEV/ PHEV & IONIQ EV/HEV/PHEV BRAKE BLEEDING

AHB System Noise

IBAU: When the driver depresses the brake
pedal, the IBAU opens a valve to transfer brake
fluid pressure from PSU to the brake calipers.
During this operation, some system noises can
be heard. Most of these noises are normal.
See below table for more information.

Noise Type
1. Honking/Hissing

2. Click/Snap/Tok

3. Beep/Squeal

4. Groan

PSU: Maintains brake fluid pressure between
160~180 bar using an electric motor. The
operation of the electric motor may cause a
normal noise to be heard during hydraulic
pressure charging.

Cause

Presence of fine air
bubbles in the system

Image

Repair
Perform brake
bleeding
procedure
described in
this TSB.

Noise when high pressure
fluid passes through the
valve
Coil vibration noise when
operating
This is not a brake squeal
from the pad/rotor
interface.

No repair
necessary,
these are
normal
system
operation
noises.

PSU motor operation
noise when charging
pressure

TSB #: 20-BR-001H

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SONATA HEV/ PHEV & IONIQ EV/HEV/PHEV BRAKE BLEEDING

Service Procedure Brake Bleeding:

 NOTE
The brake system consists of 3 distinct hydraulic sections: low pressure, high pressure, and
brake simulator sections. Because of this, the air bleeding procedure must be performed in the
sequence described below.

Air Bleeding Sequence:
Step 1: AHB System Bleeding (IBAU ECU OFF)
Step 2: AHB System Bleeding (IBAU ECU ON)
Step 3: GDS Fluid Circulation Mode
Step 4: GDS Pedal Travel Sensor Calibration
Service Procedure Brake Bleeding Step 1: AHB System Bleeding (IBAU ECU OFF)
1.

Ensure brake fluid reservoir level never
drops below the halfway point between
MIN and MAX. If the level drops below this
point, there is a risk of air being introduced
into the system, and the bleeding procedure
must be started over.

Ensure fluid level
never drops below
halfway between
MIN and MAX

 NOTE
Use DOT 3 or DOT 4 brake fluid.

TSB #: 20-BR-001H

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2.

SONATA HEV/ PHEV & IONIQ EV/HEV/PHEV BRAKE BLEEDING

Disconnect the IBAU connector (A).
A

Sonata

A

Ioniq

3.

With the air flow valve closed (as shown in image below), connect the pressurized brake
bleeder tool (09580-3D100) to the brake fluid reservoir using the adapter (0K585-E8100).
Air flow valve
(closed)

SST 0K585-E8100

Compressed air

TSB #: 20-BR-001H

SST 09580-3D100

Pressure
regulator

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4.

SONATA HEV/ PHEV & IONIQ EV/HEV/PHEV BRAKE BLEEDING

With the air flow valve closed, connect a
compressed air source. Regulate the air
pressure to 50 psi. Open the air flow valve
to pressurize the brake system.
After the system is pressurized, inspect the
integrated brake actuation unit (IBAU) and
pressure source unit (PSU) fittings for leaks.
Repair any leaks found before continuing
with bleeding procedure.

 NOTE
Always keep the air flow valve
closed when connecting to a
compressed air source. Open
the valve as the last step.
When removing pressure from
the system, close the valve first
before removing the
compressed air source.

5. With the brake system pressurized, begin the bleeding procedure starting at the bleeder located at
the PSU.
Bleed the fitting until no air bubbles appear in the fluid.
IBAU

PSU bleeder

PSU bleeder

TSB #: 20-BR-001H

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6.

SONATA HEV/ PHEV & IONIQ EV/HEV/PHEV BRAKE BLEEDING

After bleeding the PSU, move to the IBAU.
1. Start bleeding at the LOWER port. Bleed until no air appears in the fluid.
2. Then, move onto the UPPER port. Bleed until no air appears in the fluid.

1st bleed the lower
port of the IBAU.

2nd bleed the upper
port of the IBAU.
7.

Starting at the rear right wheel, attach a
clear hose to the brake bleeding nipple. The
other side of the hose should be immersed
in a bottle partially filled with clean brake
fluid.
While pressurized with compressed air,
bleed the brakes at each wheel in the correct
sequence:
1. Rear Right
2. Front Left
3. Rear Left
4. Front Right
Do not pump the brake pedal during this
procedure.
Use only air pressure to bleed. Repeat this
sequence until no air bubbles appear in the
fluid.
Remember to maintain proper brake fluid
level in the reservoir at all times.

 NOTE
Bleeder screw tightening
torque: 6.9~12.7 N.m (0.7~1.3
kgf.m, 5.1~9.4 lb-ft)

TSB #: 20-BR-001H

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8.

SONATA HEV/ PHEV & IONIQ EV/HEV/PHEV BRAKE BLEEDING

Perform a second cycle of bleeding, this time
with an assistant pressing on the brake
pedal (and the SST still applying air
pressure), as follows:
1. Starting at the IBAU lower port,
depress the brake pedal five times
and hold. Open the bleeder to bleed
out any remaining air in the system.
Close the bleeder before removing
brake pedal pressure.
2. Repeat the above procedure 10
times.
3. Move onto the upper port, and bleed
10 times in the same fashion
(applying brake pedal pressure).
4. After completing the IBAU bleeding,
move to the calipers. Start at the right
rear caliper, and bleed 10 times in the
same fashion (applying brake pedal
pressure).
5. Repeat this for the rest of the calipers
in the order previously described.
6. Remove the SST and top off the
brake fluid reservoir.

Service Procedure Brake Bleeding Step 2: AHB System Bleeding (IBAU ECU ON)
9.

Reconnect the IBAU connector.

ESC OFF button

Enable the IBAU ECU Air Bleeding Mode
according to the following:
1. Turn the ignition ON.
2. Press and hold the ESC OFF button.
Wait for the “Traction & Stability
Control disabled” message to be
displayed, and continue holding the
ESC OFF button.
3. While still holding the ESC OFF
button, depress and release the brake
pedal from rest position to fully
applied (40mm or more) 10 times.
4. Release the ESC OFF button.
5. Turn the vehicle ignition OFF.
6. Turn the vehicle ignition back ON.
7. Press and hold the ESC OFF button
until “Traction & Stability Control
disabled” is displayed.
TSB #: 20-BR-001H

IBAU ECU Air Bleeding
Mode is established
when the ABS and ((!))
lamps are illuminated.
Page 8 of 14

SUBJECT:

SUBJECT:

SONATA HEV/ PHEV & IONIQ EV/HEV/PHEV BRAKE BLEEDING
8. The IBAU ECU Air Bleeding Mode
should now be enabled. Verify by
observing that the ABS and ((!))
lamps are illuminated on the gauge
cluster.

10.

 NOTES
The IBAU Air Bleeding Mode can only be
enabled under the following conditions:
- All doors, the hood, and the trunk
or hatch must be closed.
- The procedure to enter bleeding
mode must be completed within 30
seconds.

With the IBAU Air Bleeding Mode enabled, perform the following:
For vehicles equipped with standard parking brake (non electric parking brake EPB):
1. Connect the SST and apply air pressure, as previously described.
2. Have an assistant press the brake pedal about half the stroke and hold.
3. Starting at the right rear caliper, open the bleeder screw to bleed the line.
4. Close the bleeder screw, then release the brake pedal.
5. Repeat steps 2 through 4 at least ten times, until no bubbles appear.
6. Move onto the next calipers in the correct bleeding order, and repeat the same
procedure until all four calipers have been bled.
7. Remove the SST, top off the brake fluid, and replace the reservoir cap.
8. Cycle the ignition OFF, then ON again to disable the IBAU ECU Air Bleeding Mode.

For vehicles equipped with electric parking brake (EPB):
1. Connect the SST and apply air pressure, as previously described.
2. Start at the right rear caliper.
3. Have an assistant press the brake pedal about half the stroke and hold.
4. While holding the brake pedal, have the assistant apply and release the EPB using
the switch in the vehicle.

TSB #: 20-BR-001H

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SONATA HEV/ PHEV & IONIQ EV/HEV/PHEV BRAKE BLEEDING
5. Gently tap the rear caliper with a rubber mallet to release any potential trapped air
bubbles.
6. Open the bleeder screw to bleed the line.
7. Close the bleeder screw, then release the brake pedal.
8. Repeat steps 3 through 7 at least ten times, until no bubbles appear.
9. Move to the next caliper and repeat steps 3-8 (skipping 4 and 5, which only apply to
EPB rear calipers).
10. Move onto the next caliper in the correct bleeding order, and repeat the same
procedure until all four calipers have been bled.
11. Remove the SST, top off the brake fluid, and replace the reservoir cap.
12. Cycle the ignition OFF, then ON again to disable the IBAU ECU Air Bleeding Mode.

Service Procedure Brake Bleeding Step 3: GDS Fluid Circulation Mode

 IMPORTANT
Before attempting to perform the Fluid Circulation Mode, ensure that the auxiliary battery
is fully charged (higher than 12V). If the battery is not fully charged, connect it to a
charger as needed.
11.

Connect a tablet-based GDS to the vehicle
as per the installation instructions found in
TSB 15-GI-001. Connect the VCI to the
tablet using the USB cable.

Perform the Fluid Circulation Mode, as
follows:
1. Select S/W Management.

TSB #: 20-BR-001H

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SONATA HEV/ PHEV & IONIQ EV/HEV/PHEV BRAKE BLEEDING
2. Select Fluid Circulation Mode.

3. Read the caution statement and click
OK to continue.

4. Read the summary of the process
and click OK to continue.

TSB #: 20-BR-001H

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SONATA HEV/ PHEV & IONIQ EV/HEV/PHEV BRAKE BLEEDING
5. Read the description of the process
and click OK to continue.

6. Read the conditions and cautions,
then click OK to continue.

TSB #: 20-BR-001H

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SONATA HEV/ PHEV & IONIQ EV/HEV/PHEV BRAKE BLEEDING
7. The fluid circulation process will
begin. Chattering and clunking
noises are normal. The process lasts
about 20 minutes. Click OK when
finished.

8. Check and clear any DTC(s).

Service Procedure Brake Bleeding Step 4: GDS Pedal Travel Sensor Calibration
12.

Connect a tablet-based GDS to the vehicle
as per the installation instructions found in
TSB 15-GI-001. Connect the VCI to the
tablet using the USB cable.
Perform the Pedal Travel Sensor (PTS)
Calibration as follows:

1. From the S/W Management screen,
select Pedal Travel Sensor (PTS)
Calibration.

TSB #: 20-BR-001H

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SONATA HEV/ PHEV & IONIQ EV/HEV/PHEV BRAKE BLEEDING
2. Read the summary of the process
and click OK to continue.

3. Read the description of the process
and click OK to continue.

4. Turn the ignition OFF for 10 seconds,
then ON again. Click OK to complete
the PTS calibration.

TSB #: 20-BR-001H

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