20NA071

Service Bulletin
Bulletin No.:
20-NA-071
Date:
April, 2020
TECHNICAL
Subject:
Service Engine Soon Lamp Illuminated and/or Service Power Brake Assist Message
Displayed, with DTCs P0557 or P0558 Stored
Model Year:
Brand:
Model:
Buick
Enclave
2018
XT5
2017
XT6
2020
Blazer
2019
Cadillac
Chevrolet
from
Traverse
2018
GMC
Acadia
2017 (VIN N)
Holden
Acadia
2019
VIN:
to
from
Engine:
Transmission:
All
All
to
2020
Involved Region or Country
North America, Europe, Russia, Middle East, Israel, Palestine, Chile, Ecuador, Peru,
Japan, Korea
Additional Options (RPOs)
Equipped with BRAKE SYSTEM-POWER, FRT & RR DISC, ABS, 17" (J61)
Condition
Some customers may comment that the Service Engine Soon (SES) lamp is illuminated
and/or the Service Brake Assist message is displayed on the Driver Information
Center (DIC).
A technician may find DTC P0557 or P0558 stored.
There is potential for EMI in the engine harness negatively impacting the signal from the
vacuum sensor.
Cause
The cause of the condition may be poor terminal tension at the B19B Brake Booster
Vacuum Sensor and/or the wiring from the brake vacuum sensor to the Engine Control
Module (ECM).
Correction
Replace the power brake booster vacuum hose and install a new external wiring harness,
following the Service Procedure below.
Copyright 2020 General Motors LLC. All Rights Reserved.
Page 2
April, 2020
Service Procedure
Bulletin No.: 20-NA-071
LFY Hose
Note: Examples of the 3 different designs for the
power brake booster vacuum hoses are shown in the
graphics below.
5549615
5549611
LGX Hose
5549612
LCV Hose
Note: Please print the Matrix below and use it for
reference while completing steps #16-22 of the Service
Procedure,
Bulletin No.: 20-NA-071
April, 2020
Page 3
Matrix
Application/Circuit/Wire Color/ECM Connector/ECM Terminal
New wire harness lead tag ID's
6270
6271
6272
Wire Color
Vt/Ye
Gn/Vt
Bk
Circuit Number
6030
6031
6032
Body Harness Color
Ye/Vt
Ye/Rd
Bk/Ye
ECM Connector
X1
X1
X1
ECM Terminal
65
45
44
Circuit Number
6030
6031
6032
Body Harness Color
Ye/Vt
Ye/Rd
Bk/Ye
ECM Connector
X1
X3
X3
ECM Terminal
32
15
20
Circuit Number
6030
6031
6032
Body Harness Color
Ye/Vt
Ye/Rd
Bk/Ye
ECM Connector
X1
X1
X1
ECM Terminal
65
45
44
Circuit Number
6030
6031
6032
Body Harness Color
Ye/Vt
Ye/Rd
Bk/Ye
ECM Connector
X1
X3
X3
ECM Terminal
32
15
20
LGX/LFY - V6 only
Acadia, XT5, XT6, Traverse, Enclave, Blazer
LCV - 4 Cyl. only
Acadia
LGX - V6 only
Holden Acadia
LCV - 4 Cyl. only
Holden Acadia
1. Remove and discard the power brake booster
vacuum hose. Refer to Power Brake Booster
Vacuum Hose Replacement, in SI.
5549616
Page 4
April, 2020
Bulletin No.: 20-NA-071
5549617
Note: The top graphic shows the LGX connector
intact; the bottom one shows the LFY wiring
already cut.
Note: Not all applications will have a cover on the
connector.
4. Remove conduit and cover from the old connector.
2. Locate the power brake booster vacuum sensor
electrical connector. Fold conduit back and cut off
connector, leaving approximately 5.0 cm (2.0 in) of
wiring on the engine harness side.
3. Tape the cut wiring end to the engine harness.
These wires will no longer be used.
5549620
5. Apply tape to connector end of the new harness,
leaving enough length as was on original
connector to allow for 90 degree elbow bend, if
applicable.
5549619
Bulletin No.: 20-NA-071
April, 2020
5549621
6. Install old conduit piece, connector cover and
apply abrasion resistant tape over the conduit up to
the new connector end.
7. Install the new power brake booster vacuum hose.
Refer to Power Brake Booster Vacuum Hose
Replacement, in SI.
8. Plug in the new harness to the power brake
booster vacuum sensor electrical connector.
Note: It is not necessary to reposition the radiator
surge tank on all applications.
Page 5
5549624
Note: The LFY harness routing is shown in the top
graphic, the LGX routing is shown in the bottom math
file. The routing for LCV is similar to the routing of
the LGX.
10. Start routing the new harness alongside the engine
harness.
9. Remove the mounting bolt and reposition the
radiator surge tank away from the cowl. Refer to
Radiator Surge Tank Replacement, in SI.
5549626
5549622
11. Unplug the X1 ECM connector (blue) from the
ECM, for LGX and LFY. Also unplug ECM
connector X3 on LCV engine applications.
12. Cut back some of the tape on the connector wiring
to expose more wiring.
13. Using a suitable pry tool, remove the cover from
the connector.
Page 6
April, 2020
5549627
14. Using terminal release tool J-38125–12A, or
similar tool, remove the terminated leads from
circuits #6030, #6031 and #6032 from the X1
connector.
Bulletin No.: 20-NA-071
5549630
16. Locate the wire labeled #6270 on the new harness
and install that terminated lead into the location in
connector X1, where circuit #6030 was located.
17. Locate the wire labeled #6271 on the new harness
and install that terminated lead into the location in
connector X1, where circuit #6031 was located.
18. Locate the wire labeled #6272 on the new harness
and install that terminated lead into the location in
connector X1 where circuit #6032 was located.
5549629
Note: In this step, do NOT cut the terminal off of
circuit #6032 (circled in yellow in the graphic
above).
15. Cut off the terminated leads that were in circuits
#6030 and #6031 and fold and tape off the ends
(circled in red in the graphic above). These circuits
will no longer be used.
5549631
Important: There are multiple ground circuits tied
to ECM ground circuit #6032 and the existing
vehicle harness wire MUST be spliced into the new
harness.
19. Cut the terminal off the new harness wire
labeled #6272.
20. Cut the engine harness ground circuit #6032
approximately 7.6 cm (3.0 in) from the ECM
connector body.
Bulletin No.: 20-NA-071
April, 2020
Page 7
21. Strip the end of all three of these wires, leaving
enough length to make a splice in the butt
connector.
22. Twist the engine harness side of circuit #6032 with
the new harness #6272 and insert in the butt
connector and crimp.
23. Insert circuit #6032 wire from the ECM connector
into the butt connector and crimp.
24. Apply heat to shrink and seal the butt connector to
complete the splice. Refer to Wire to Wire Repair,
in SI.
5549633
Note: Graphic shown above is LFY harness routing.
5549632
25. Reposition the wiring to the connector and using
abrasion resistant tape, apply tape up to the flip
door of the ECM connector.
26. Reinstall the cover to the connector.
27. Reconnect the ECM connector(s).
5549634
Note: Graphic shown above is LGX harness routing,
with LCV being similar.
Important: It will be necessary to coil the extra wire
length. Ensure the wire is tied back away from any
sharp edges or moving parts that could cause
damage to the harness.
28. Secure the new harness to the engine wiring
harness using at least 5 or 6 tie straps.
29. Check and clear any DTC’s, as necessary.
Page 8
April, 2020
Bulletin No.: 20-NA-071
Parts Information
Use the VIN and refer to the GM Electronic Parts
Catalog (EPC) to determine the proper part to order.
Causal
Part
Description
Part
Number
Qty
N/A
WRG HARN
84441605
1
X
HOSE ASM-P/B
BOOS VAC
84265637
84341899
84210413
1
N/A
SALMON SPLICE
19300089
1
Warranty Information
For vehicles repaired under the Bumper-to-Bumper
coverage (Canada Base Warranty coverage), use the
following labor operation. Reference the Applicable
Warranties section of Investigate Vehicle History (IVH)
for coverage information.
Labor Operation
Description
Labor Time
2486068*
Replace Power Brake Booster Vacuum Hose Assembly and
Install Wiring Harness
LFY – 1.0 hr
LGX or LCV – 1.3 hrs
*This is a unique Labor Operation for Bulletin use only.
Version
2
Modified
Released March 20, 2020.
Released April 16, 2020 – Corrected Salmon Splice Part Number.
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these
technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper
service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a
job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your
vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the
information.
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