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Rob Reasor    0

We have a 1999 Mack ch613 with an e7 427 motor. We have had a number of shutdowns while the truck is moving at highway speeds. It just stops running. Electronic malfunction and engine shutdown light comes on and we have to turn off key and restart after getting to the side of the road. Yesterday it threw a 6-4 code that points to a j1939 code. I have read the service bulletin and blog on this and am confused. One says that it is a ground issue (SB221032) and one says ABS short or malfunction. Where do we start to fix this issue.

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turckster    66

Mack blink code 6-4 from Mack Electronic Information System:

Failure Mode Identifier FMI: 8 (Abnormal)

Parameter Identification: S231

Message Identification MID: 128 (Abnormal), 142 (Abnormal)

Circuit Description: The V-MAC III system uses the J1939 data line to control communication between the Vehicle Electronic Control Unit (VECU), Engine Electronic Control Unit (EECU), Anti-lock Brake System Control Unit, Allison Transmission Control Unit, and accessory systems, depending on vehicle model and option content. The J1939 data line is an expandable data bus, allowing the addition of accessory control modules (Collision Avoidance, Traction Control, etc.) to be connected to the circuit. The J1939 data line is comprised of two circuits; the L circuit and the H circuit. The two wires are twisted together to prevent outside electrical noise from interfering with the data being carried by the L and H circuits. The V-MAC III system is designed to allow continued engine operation with the loss of the J1939 data line signal as long as the J1587 data line is still operational.

Code Setting Conditions: If either the Vehicle Electronic Control Unit (VECU) or the Engine Electronic Control Unit (EECU) loses communication on the J1939 data line for more than one half second, code 6-4 will set and the Electronic Malfunction Lamp (EML) will turn on. The fault will become inactive if communication resumes for at least on half second. When code 6-4 is active, engine speed will default to 900 RPM. If communication is lost on both the J1587 and J1939 data lines the engine will not run.


Fault code 6-4 will set for some mismatches of VECU and EECU software levels. Blink code 6-4 will also set while the VECU is in the programming mode for Customer Data, Fleet Data, or Mack Data. This code setting condition is normal and the code will become inactive after the ignition key is cycled.


Fault code 6-4 may log, without illuminating the Electronic Malfunction Lamp (EML), on vehicles equipped with Eaton/Bosch ABS/ATC module # 7MN54M2. This nuisance code will not affect the performance of the vehicle. When a vehicle equipped with this ABS/ATC module is being diagnosed for an inactive code 6-4, contact Mack Trucks Service Engineering.

Additional Symptoms: The engine will not start, if communication is lost on both the J1587 and J1939 data lines. If communication is lost on just the J1939 line, the engine will only run at 900 RPM.

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