So I am having a random problem with the 3X board and is injector drivers. This has now happened on 3 different cars in the same manner seemingly totally a random.
All of the injectors have been either the newer bosch EV14 style (9.5ohm)
or the Siemens Deka units which ohm out a little higher(11.2-11.5). All high impedance. On my personal car I ran the bosch EV14 injectors in batch fire with MS2 via the v3 injector drivers as high imp with no problems for over a year. Switched to MS3x and the car drove flawlessly for 6+ mo every day, then one day driving home and injector channel got stuck open (channel C) (verified with LED tester on the side of the highway). That 3x board was from one of the original group of 50, so I just replaced it and called it a manufacturing defect and car had been fine since.
After several months of running it happened on my car again, this time channel A
Another customer's car of mine with a brand new 3+3x from DIY (prebuilt) and it worked for a few hours and then died on the dyno. channel D.
3 different sets of injectors 3-4 different boards, two cars
I did some poking around on the 3x board last night and I found the fault is with the transistor for the inj channel. The signal gets to the transistor gate just fine and the source ground is intact. If I lift the gate side of the transistor from the 3x pad so it is just connected to the source and the drain (using JimStimX) the LED remains lit. If I remove the ground (source) from the transistor, the led goes out. It is like the gate of the transistor is stuck in the ON state.