Hyundai Ioniq: AHB(Active Hydraulic Boost) System / Hydraulic Power Unit. Repair procedures

Hyundai Ioniq (AE) 2017-2025 Service Manual / Brake System / AHB(Active Hydraulic Boost) System / Hydraulic Power Unit. Repair procedures

Removal

1.	Turn ignition switch OFF and disconnect the negative (-) battery cable.

2.	Remove the wiring bracket.

Remove the brake fluid from the reservoir with a syringe.

•	Do not spill brake fluid on the vehicle, it may damage the paint; if brake fluid does contact the paint, wash it off immediately with water.

•	To prevent any dust entering in the reservoir, the reservoir cap should be closed again after removing brake fluid.

Loosening the flare nut (A) and then disconnect the brake tube.

Tightening torque :

13.7 - 16.7 N.m (1.4 - 1.7 kgf.m, 10.1 - 12.3 lb-ft)

•	Before removing the brake tube, high pressure in an accumulator of PSU should be reduced for safety by conducting "High pressure release mode" of GDS connected to LF HEV.

5.	Disconnect the PSU connector.

6.	Remove the front sub frame. (Refer to Suspension System - "Sub Frame")

Loosen the mounting bolt and nut then remove the PSU.

Tighten torque :

19.6 - 29.4 N.m (2.0 - 3.0 kgf.m, 14.5 - 21.7 lb-ft)

Installation

1.	Installation is the reverse of removal.

2.	Tighten the PSU bracket bolts and brake tube to the specified torque.

3.	After filling the brake fluid in the reservoir, perform the air bleed. . (Refer to AHB System - "AHB System Air Bleeding")

4.	Conduct Pressure sensor Calibration.

5.	Check the brake pedal operation.

Diagnostic Procedure Using GDS

The following section describes how to diagnose faults using a diagnostic instrument.

1.	Connect the diagnostic instrument to the self-diagnostic connector (16-pin) beneath the crash pad on the side of driver's seat, and then turn on the ignition to activate the diagnostic instrument.

2.	In the GDS Vehicle Type Selection menu, select "Vehicle Type" and "ABS/ESC" System, and then opt for "OK." [Pressure Sensor Calibration]

3.	Turn ignition switch off and on after calibration procedure.

4.	Confirm success of calibration.

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