Invalid application MC43

The most plausible explanation for a 4:2 blink on an MC4x module togehter with the dialogues "no valid application" is reverse feed of the module.  4:2 means 4 red, 2 yellow and then a longer sequence of yellow flashes.

See: 

http://www.parker.com/literature/Electronic%20Controls%20Division/Literature%20files/IQAN-MC4x_HY33-8413-IB_UK.pdf

Reverse feed will occur if the output highsides or returns are shorted to battery voltage, the module checks for this error at startup, and if it is present it does not continue to the step next of launching the application. So "no valid application" is not actually meaning that the application has to be invalid, it is a message you get when the application prevented from being loaded due to some fault while the lower level firmware is still running. 

I am however not 100% sure that reverse feed is the fault that has occurred in your system, the flashes that follow after the first 4:2 can differ depending on firmware version and other factors, but I think that with version 5.01 in the MC43 it should read 4:2:1:1:1 if the problem is caused by reverse feed. I'll check!

One thing that I recommend you try in the meantime is to bypass the application (see chapter 8), if the problem is caused by something in the application the MC43 blink would then change to "application not loaded". 

Thanks a lot for your support and detailed explanation.

We have finally replaced the module, cause we had little time for further tests on the actual machine, and everything seems fine on the connector and wire harnesses.

New one works OK.

Back at the office, we tested the MC43 but it keeps doing exactly the same (this time only supply, IDTag and CAN for diagnosis).

So some kind of hardware problem may exist.

We will contact local support for RMA request, but we can do any test in the meantime if you tell us to.

Thanks a lot again.

Thanks you, I checked the blink code and it does point towards a hardware error related to the output diagnostics, another factor that would prevent the application from starting. 

We would like to investigate the module here to understand what the actual problem could be, at this moment I cannot think of any additional test that you could do on your end. 

Please go ahead and get in touch with the local Parker sales office to get the module returned.

An MC43 module can get the 4:2:2:1:3 blink as an effect of cranking if used in a weak 12 V system. 

In this particular case however, the reason was a damage on an output, but I am unable to explain what would cause such damage.