Replacing an Auto Baud Rate Detecting Bulkhead Module
with a Fixed Baud Rate BHM
FLA COE
FLB COE
FLD Conventional
Business Class
FLC 112 Conventional

Century Class Conventional
Argosy
Cargo
Columbia

122SD and Coronado
> Business Class M2
Cascadia
> 108SD/114SD

54-295
Freightliner
Service Bulletin

Description of Revisions: This bulletin replaces the version dated
02/01/2016. Information about auto baud rate connections has
been included.

General Information
Vehicles built beginning January 2, 2016 through January 18, 2021 use a bulkhead module (BHM) with
automatic baud rate detection for the primary J1939 network. If a BHM needs replacement, it must be replaced
with the correct BHM for the primary J1939 datalink’s operating speed.
• Vehicles with a green diagnostic connector have a 500kbps J1939 datalink for engine diagnostics. These
vehicles use part number A66-03086-003.
• Vehicles with a black diagnostic connector have a 250kbps J1939 datalink for engine diagnostics. These
vehicles use part number A66-03086-002.

IMPORTANT: Using the incorrect part number may cause a no-start condition.
IMPORTANT: It is normally not necessary to replace the BHM. Replacing the BHM should be a last
resort to solving electrical problems, unless the unit needs replacing due to physical damage.

Replacement
1. Open the hood.
2. Disconnect the negative leads from the batteries. See Fig. 1.

Freightliner Service Bulletin, 07/28/2022

Page 1

54-295

Replacing an Auto Baud Rate Detecting Bulkhead Module
with a Fixed Baud Rate BHM

Freightliner
Service Bulletin

FLA COE
FLB COE
FLD Conventional
Business Class
FLC 112 Conventional

Century Class Conventional
Argosy
Cargo
Columbia

122SD and Coronado
> Business Class M2
Cascadia
> 108SD/114SD

4
5
3

6
2
7
1

8
09/26/2001

1.
2.
3.
4.
5.
6.
7.
8.

f543870

B1, Forward Chassis Harness
B2, Engine Harness
B3, Frontwall Harness
B4, Frontwall Harness
Frontwall
B5, Dash Harness
B6, Dash Harness
B7, Dash Harness
Fig. 1, Bulkhead Module Harness Connections

NOTE: The bulkhead module is located on the frontwall slightly below and outboard of the steering
column.
3. Disconnect bulkhead harnesses B1 through B4 from the engine side of the frontwall. See Fig. 2.

Page 2

Freightliner Service Bulletin, 07/28/2022

Replacing an Auto Baud Rate Detecting Bulkhead Module
with a Fixed Baud Rate BHM
FLA COE
FLB COE
FLD Conventional
Business Class
FLC 112 Conventional

Century Class Conventional
Argosy
Cargo
Columbia

54-295
Freightliner
Service Bulletin

122SD and Coronado
> Business Class M2
Cascadia
> 108SD/114SD

1

3
2
4

5
09/25/2001

1.
2.
3.
4.
5.

f543915

Wiper Linkage Arm
Bulkhead Module
Hood Support Bracket
Quarter Fender
Power Distribution Module
Fig. 2, Bulkhead Module from the Engine Side

4. Disconnect bulkhead harnesses B5 through B7 from the bulkhead module on the cab side of the frontwall.
See Fig. 3.

Freightliner Service Bulletin, 07/28/2022

Page 3

54-295

Replacing an Auto Baud Rate Detecting Bulkhead Module
with a Fixed Baud Rate BHM

Freightliner
Service Bulletin

FLA COE
FLB COE
FLD Conventional
Business Class
FLC 112 Conventional

Century Class Conventional
Argosy
Cargo
Columbia

122SD and Coronado
> Business Class M2
Cascadia
> 108SD/114SD

2

1
3

4

5

09/25/2001

1.
2.
3.
4.
5.

f543916

Driver Footwell Kick Panel
B5, Dash Harness
B6, Dash Harness
B7, Dash Harness
Bulkhead Module
Fig. 3, Bulkhead Module from the Cab Side

5. Remove the tread plate from the driver door entry.
6. Remove the kick panel from the left side of the driver footwell.
7. Remove the five Torx® capscrews that secure the BHM to the cab side of the frontwall, then remove the
BHM by pulling it through the opening into the cab.
8. Place the new BHM through the frontwall opening from the cab side, then secure it with five Torx capscrews
and torque them 48 lbf·in (540 N·cm).
9. Install the kickpanel in the left side of the driver footwell and secure it with Torx capscrews.
10. Install the tread plate at the driver door entry.
11. Connect the bulkhead harnesses B5 through B7 to the BHM on the cab side of the frontwall.
12. Connect the bulkhead harnesses B1 through B4 to the BHM on the engine side of the frontwall.

IMPORTANT: The ignition and the battery switch must be in the ON position before the batteries are
connected.
13. Turn the ignition switch to the ON position.
14. Turn the battery cutoff switch (if equipped) to the ON position.
15. Connect the batteries.
16. Close the hood.

Page 4

Freightliner Service Bulletin, 07/28/2022

Replacing an Auto Baud Rate Detecting Bulkhead Module
with a Fixed Baud Rate BHM
FLA COE
FLB COE
FLD Conventional
Business Class
FLC 112 Conventional

Century Class Conventional
Argosy
Cargo
Columbia

122SD and Coronado
> Business Class M2
Cascadia
> 108SD/114SD

54-295
Freightliner
Service Bulletin

17. Flash the new BHM. Refer to Section 54.12, Subject 110 for the Business Class M2 Workshop Manual, or
Section 54.07, Subject 110 for the 108SD/114SD Workshop Manual.

Warranty
This is an informational bulletin only. Warranty does not apply.

Freightliner Service Bulletin, 07/28/2022

Page 5