GROUP

NUMBER

CAMPAIGN
DATE

Technical Service Bulletin
SUBJECT:

MAY 2023

23-01-036H
MODEL(S)
ELANTRA (CN7A)
SONATA (DN8A)
SANTA FE (TMA)

HECU MODULE DARK CURRENT MEASUREMENT AND
REPLACEMENT (SERVICE CAMPAIGN 990)

 IMPORTANT
Dealers must perform this service campaign on all affected vehicles prior to customer retail delivery
and whenever an affected vehicle is in the shop for any maintenance or repair.
Access the “Vehicle Information” screen via WEBDCS to identify open campaigns.
Description: Some Elantra (CN7A), Sonata (DN8A) and Santa Fe (TMA) vehicles may exhibit the
Electronic Parking Brake (EPB) warning light on due to brake fluid entering the HECU electrical
connector. DTC C1501 (EPB Switch Failure) may be present, but EPB performance remains
unaffected. This bulletin describes the procedure to inspect, and if necessary, replace the Hydraulic
Electronic Control Unit (HECU).

STUI
This TSB includes STUI pictures as a requirement. Where indicated, please include the last 6
digits of the VIN and date of repair on a piece of paper. Ensure the VIN and date of repair are
clearly visible. Finally, please ensure the captured pictures are completed according to the steps
in this TSB and uploaded to STUI. All claims submitted that have an illegible, incomplete, missing,
or incorrect picture are subject to debit.
Applicable Vehicles (Certain):
 2022MY Elantra (CN7A) equipped with 2.0L engines produced 12/09/2021 - 02/14/2022 (VINs
beginning with “5NP”).
 2022MY Sonata (DN8A) equipped with 1.6T and 2.5L engines produced 12/01/2021 04/12/2022 (VINs beginning with “5NP”).
 2022MY Santa Fe (TMA) equipped with 2.5L and 2.5T engines produced 11/30/2021 03/21/2022(VINs beginning with “5NM”).
Circulate To: General Manager, Service Manager, Parts Manager, Warranty Manager, Service
Advisors, Technicians, Body Shop Manager, Fleet Repair

SUBJECT:

HECU MODULE DARK CURRENT MEASUREMENT AND REPLACEMENT (SERVICE CAMPAIGN 990)

Parts Information:
Model

Part Name

Original P/N

New P/N

QTY.

Elantra
(CN7A)

Hydraulic Unit Assy ESCI+

58910-AB800

58910-AB800QQH

1

Sonata
(DN8A)

Hydraulic Unit Assy ESCI+

58910-L0100

58910-L0100QQH

1

Santa Fe 2.5L
(TMA)

Hydraulic Unit Assy ESCI+

58910-S2DA0

58910-S2DA0QQH

1

Santa Fe 2.5T
(TMA)

Hydraulic Unit Assy ESCI+

58910-S2GA0

58910-S2GA0QQH

1

SST Information:
Tool Name

Part Number

Figure

Multimeter
DT-830D+

HK589-DT830QQH

NOTE: Each dealer has been provided 1 multimeter for the start of the campaign.

TSB #: 23-01-036H

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SUBJECT:

SUBJECT: HECU MODULE DARK CURRENT MEASUREMENT AND REPLACEMENT (SERVICE CAMPAIGN 990)

Warranty Information:
Model

Op. Code

Operation

Op.
Time

20DA25R0

HECU Dark Current Inspection
ONLY (below max value)

0.3 M/H

20DA25R1

HECU Dark Current Inspection
(equal to or above max value)
and HECU Replacement

1.5 M/H

20DA25R3

HECU Dark Current Inspection
ONLY (below max value)

0.3 M/H

20DA25R4

HECU Dark Current Inspection
(equal to or above max value)
and HECU Replacement

1.5 M/H

20DA25R6

HECU Dark Current Inspection
ONLY (below max value)

0.3 M/H

20DA25R7

HECU Dark Current Inspection
(equal to or above max value)
and HECU Replacement

1.5 M/H

Elantra
(CN7A)

Sonata
(DN8A)

Santa Fe
(TMA)

Causal Part

Nature
Code

Cause
Code

I3B

ZZ3

58910AB800QQH

58910L0100QQH

58910S2DA0QQH

NOTE 1: Submit Claim on Campaign Claim Entry Screen
NOTE 2: If a part that is not covered by this recall is found in need of replacement while performing Service
Campaign 990 and the affected part is still under warranty, submit a separate claim using the same repair
order. If the affected part is out of warranty, submit a Prior Approval request for goodwill consideration prior to
performing the work.
NOTE 3: Op time includes taking pictures using STUI and uploading. The STUI picture must include the dark
current measurement and junction box open with a piece of paper displaying the last 6 digits of the VIN and the
date of repair. An additional STUI picture (based on inspection) is required of the newly installed HECU along
with the removed original HECU with the last 6 digits of the VIN and the date of repair. If not included, claim
will be subject to debit.
NOTE 4: The incident parts are subject to callback through the normal Warranty Technical Center (WTC) parts
return process. Claim is subject to debit if the part is not returned.

Information

i



If the “ABS”, “ESC” or “Brake” indicator lamps are illuminated, refer to the
appropriate section of the repair manual prior to performing this TSB inspection.
Images below are taken from a Santa Fe Sport (AN) vehicle. While other models
will have slight variations in configuration, the service procedure is identical.

TSB #: 23-01-036H

Page 3 of 9
SUBJECT:

SUBJECT:

HECU MODULE DARK CURRENT MEASUREMENT AND REPLACEMENT (SERVICE CAMPAIGN 990)

Service Flowchart:

Service Inspection Guidance:
Model
Elantra
(CN7A)
Sonata
(DN8A)
Santa Fe
2.5L
(TMA)
Santa Fe
2.5T
(TMA)

Part Number

Part Name

Fuse Measurement
Point

Maximum Dark
Current Value

58910-AB800

Hydraulic Unit Assy

40A (ABS)

95 µA

58910-L0100

Hydraulic Unit Assy

40A (ABS)

95 µA

58910-S2DA0

Hydraulic Unit Assy

30A (ABS)

95 µA

58910-S2GA0

Hydraulic Unit Assy

30A (ABS)

105 µA

TSB #: 23-01-036H

Page 4 of 9
SUBJECT:

SUBJECT: HECU MODULE DARK CURRENT MEASUREMENT AND REPLACEMENT (SERVICE CAMPAIGN 990)

Fuse Box Cover Measurement Point Guide:
Elantra (CN7A): 58910-AB800

Sonata (DN8A): 58910-L0100

Santa Fe (TMA): 58910-S2DA0 / 58910-S2GA0

Service Procedure:
1.

Record customer’s radio presets.

NOTICE

Turn off the vehicle, close all doors, and wait at
least 3 minutes after IGN OFF (to enter ESC
Sleep mode).
*If the door is open while in standby, sleep
mode will not activate.

TSB #: 23-01-036H

Do not “Start” the engine at any time
during the test procedure. Doing so will
yield inaccurate dark current
measurement results.

Page 5 of 9
SUBJECT:

SUBJECT:

2.

HECU MODULE DARK CURRENT MEASUREMENT AND REPLACEMENT (SERVICE CAMPAIGN 990)

Disconnect the battery negative (-) terminal
and remove the junction box fuse cover.
Negative (-) Battery Terminal Nut
Tightening Torque:

lb‐ft • 3.0‐4.4
kgf.m • 0.4‐0.6
N.m • 4.0‐6.0

3a.

Sonata (DN8A) and Santa Fe (TMA)
vehicles:
Remove the 10 mm nut and lift the junction
cable over the stud.
Remove both multi-fuses.
Locate the ABS fuse location in the junction
box (see the Fuse Box Measurement Point
Guide).
Re-install the multi-fuse that does not interfere
with the dark current measurement (leaving
the measurement point open and accessible).
Reconnect the junction cable using the 10mm
nut.

i

Information

DN8A vehicles: The ABS fuse
measurement location is under the right
multifuse bar.
TMA vehicles: The ABS fuse
measurement location is under the left
multifuse bar.

TSB #: 23-01-036H

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SUBJECT:

SUBJECT: HECU MODULE DARK CURRENT MEASUREMENT AND REPLACEMENT (SERVICE CAMPAIGN 990)

3b.

Elantra (CN7A) vehicles:
Locate the ABS fuse location in the junction
box (see the Fuse Box Measurement Point
Guide).
Use the fuse puller to remove the 40A ABS
fuse.

4.

Set the multi-meter to the 200 µA setting.
Connect the probe leads as shown – black in
the center COM terminal, red on the right side
VΩmA terminal.

TSB #: 23-01-036H

Page 7 of 9
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SUBJECT:

5.

HECU MODULE DARK CURRENT MEASUREMENT AND REPLACEMENT (SERVICE CAMPAIGN 990)

Contact the red lead to the positive (+) battery
terminal.
Contact the black lead to the appropriate ABS
fuse location (see the Fuse Box Measurement
Point Guide).
Positive
Terminal “+”

6.

ABS

Measure the Multimeter value/reading for
at least 30 seconds. The current draw value
must stay consistent for a proper
measurement.

NOTICE
Take care to not damage the
terminals.

7.

STUI
Using STUI, take a photo showing the
multi-meter dark current reading, and
the open junction box. Include the last
6 digits of the VIN and the date of repair
on a piece of paper.
Upload the photo to STUI.

Example of STUI Photo

TSB #: 23-01-036H

Page 8 of 9
SUBJECT:

SUBJECT: HECU MODULE DARK CURRENT MEASUREMENT AND REPLACEMENT (SERVICE CAMPAIGN 990)

8.



If current draw value is below the
maximum dark current value as listed
above in the Service Inspection
Guidance on page 4:
o Reinstall the removed parts in
the reverse order. No further
action is required.



If current draw value is equal to OR
over the maximum dark current value
as listed above in the Service
Inspection Guidance on page 4:
o Replace the Hydraulic Electronic
Control Unit Assy (HECU) by
referring to the shop manual.

i

Information

All part orders are on manual
allocation.

STUI
If HECU is replaced: Using STUI, take a
photo showing the newly installed
HECU, along with the removed original
HECU. Include the last 6 digits of the
VIN and the date of repair on a piece of
paper.
Upload the photo to STUI.
Example of STUI Photo
9.

Reassemble vehicle in the reverse order of
removal.

10.

Start the engine. Confirm the “ABS”, “ESC”
and “Brake” indicator lamps are not
illuminated, clear any incidental DTCs and
reprogram the customer’s radio preset
stations.

11.

The service procedure is now complete.

TSB #: 23-01-036H

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