S4437- 202502 Service Campaign

Service Campaign S4437
February 2025
Mack MMDE GVCU Software

Service Category Service Department

Section Function Group 360

Technician Skill Level A
Market: North America
Applicability

Mack

Model Years

2024-2025
Models

MMDe
Introduction

Mack Trucks has identified that certain MMDE model trucks may encounter charging

issues when using a Heliox brand charger. To address this, a General Vehicle Control Unit

(GVCU) software update has been developed. Please refer to the instructions in this

document to install the update.

Production Change Information

This bulletin applies to vehicles built within the specified production changes below.

Brand

Engine

Emission Level Starting Build Date Ending Build Date

Mack

BEV

EM-ZE

21-June-2023

24-October-2024

Warranty Information

This repair is covered by an authorized Service Program.

Reimbursement is obtained through the normal claim handling process.

Claim Type (used only when uploading from the Dealer Bus. Sys.)

B

Main Labor Code
Description
Hours
1720-16-09-01
Campaign, General 0.1x10
1.0
Causal Part

SCC Authorization

Code
24444477
Expiration Date
February 28, 2026
S4437
Service Campaign S4437
February 2025
Mack MMDE GVCU Software

Required Software Application

To update the GVCU software, you’ll need an application called cvFlash. If you haven’t

already downloaded it to your PC, please access the cvFlash file and download

instructions in the Trucks Dealer Portal. The images below show where to find the files

in TDP.
Service Campaign S4437

Mack MMDE GVCU Software
February 2025
Service Campaign S4437
February 2025
Mack MMDE GVCU Software

Required Tools and Equipment

All tools and equipment listed below are essential tools for BEV dealers. If you do not

already have them, they can be ordered through Parts LinQ. Dealer is responsible for

essential tool cost and will NOT be covered by this campaign.

Description
Part Number
CV Flash License
88800874
PCAN USB Dongle
88800873
PCAN Harness
88800876
SEA Diagnostic Harness
88800877
Image
Service Campaign S4437
February 2025
Mack MMDE GVCU Software

eService Case

To receive the software file for the GVCU you will need to create an eService case under

Emobility Technical Support. Please include the following

• Campaign number SXXXX and title (Mack MMDE GVCU Software).

• VIN number.

Important Note

An eService case is required for every truck, even if your dealer is performing this campaign

on multiple trucks.

Important Note

Note the title of the received file and save to a known location on you PC where you can

easily access.

Repair Procedure

Important Note

Before proceeding with the repair, ensure you have the cvFlash application, all needed

equipment, and have received the software file from eService.

1.

2.

3.

4.

5.
Park the vehicle on a level surface.

Apply parking brake.

Place the transmission in park or neutral.

Turn off the ignition.

Install wheel chocks.
6. Connect the cvFlash license flash drive to your PC.
Service Campaign S4437
February 2025
Mack MMDE GVCU Software

7. Connect the PCAN USB dongle to your PC.
8. Connect the PCAN harness to the PCAN box.
9. Connect the other side of the PCAN harness to the connector labeled CAN 1 on SEA

diagnostic harness.
Service Campaign S4437
February 2025
Mack MMDE GVCU Software

10. Remove the access panel.
11. Locate the 12 pin SEA diagnostic plug located inside of the access panel.

Important Note

If you cannot locate the SEA diagnostic connector via the access panel, removal of the kick

panel may be necessary.

12. Connect the diagnostic plug to the SEA diagnostic harness.
Service Campaign S4437
February 2025
Mack MMDE GVCU Software

13. Open cvFlash on your PC.
14. Open the File tab and click on Open Project Package.
Service Campaign S4437
February 2025
Mack MMDE GVCU Software

15. Locate and select the save file received from eService.
16. You should now see the ‘Flash Run’ sub-menu populated with information. If no

information is populated, repeat steps 14 and 15.
Service Campaign S4437
February 2025
Mack MMDE GVCU Software

17. Confirm that the drop-down menu next to “Initial” (Outlined in red below) is set to

500000.
18. Select the Comm. Config tab.
Service Campaign S4437
February 2025
Mack MMDE GVCU Software

19. Ensure that UDSonCAN is selected in the “Protocol” drop-down, and PCAN USBBUS is

selected in the “Port” drop-down.
20. Click “Refresh Ports”.
Service Campaign S4437
February 2025
Mack MMDE GVCU Software

21. Check to ensure that the canDeviceTxID and canDeviceRxID values in the “Driver” tab
are correct. They should both begin with 0x18. If you see 0x98, change the nine to a

one.
22. Select the Flash Run tab.
Service Campaign S4437
February 2025
Mack MMDE GVCU Software

23. Turn the ignition key to the “ON” position.
24. Select “Start” in the Flash Run tab.
Service Campaign S4437
February 2025
Mack MMDE GVCU Software

25. Once the flash procedure has started, a progress bar will appear. Pictured below.
26. Once the status bar has reach 100% the message “Validating Download” will appear
above the status bar (Image One). DO NOT exit at this point. The flashing procedure is

not complete until the status bar goes away and the message “Download completed

Successfully” appears in the bottom lefthand corner (Image Two).
Service Campaign S4437

Mack MMDE GVCU Software
27. Exit cvFlash.
28. Turn ignition key off.

29. Wait 10 seconds.

30. Turn ignition key on.
February 2025
Service Campaign S4437

Mack MMDE GVCU Software

31. Remove the wheel chocks.
32. Release the truck.
February 2025

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Last update on 2026-05-12 / Affiliate links / Images from Amazon Product Advertising API

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