I have a 1994 model CHR with EN7-400 V-MAC engine.
Occasionally the engine will shut down, without warning, for no reason.
When it happens, I get two fault codes:
6-2 Date Line Input (Proprietary) no signal.
6-3 SAE/ATA J1708 Serial Line No Signal.
If it shuts down while driving, turning the key off and then on again will often reset it, and while in motion it will roll start. But sometimes it won't, and you have to start it with the starter motor. Which is normally not ideal to do while trying to drive, corner, in traffic, etc.
I have been given the troubleshooting chart for the two codes from Mack. But the trouble is, that when it is in the workshop, the fault codes are not present, and the tests all show that it is all working properly. If it shuts down in a convenient place in the yard, I can run the tests, but the steps say that you have to turn off the key before unplugging the loom from the ECM, and doing this always resets it and then there is nothing wrong again.
There is no pattern to the random shut downs - hot day, cold day, pulling hard, pulling light, coasting, engine brake on, engine brake off, top gear, middle gear, occasionally during a gearshift, occasionally while idling.
Sometimes it may do hundreds of kilometres without fault, then do it a few times within a couple of hours. It's rather annoying.
I have checked over the loom visually, and repaired a couple of slightly rubbed wires, replaced a pin in the ECM connector, but it is very difficult to access all of the loom.
Any suggestions? Any problem spots in the loom that I may not be aware of?