MC3 Output Error on Start Up

Ethan Zeman 6 years ago in Master modules / MC3 updated by Gustav Widén (System support) 6 years ago 4

One of our field units is getting the an "Error" on start-up. It occurs on every startup.

After the error is cleared, everything is working fine. The solenoid(s) showing the error function with no issue.

In the past we have seen open load and overload output errors but not just a generic error message. We replaced the MC3 module and the problem was resolved.

Just curious on what this means? Thanks

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Really Just Guessing on my Part: the solenoid (SOL) that moves the valve is not responding as expected, so the firmware is saying the solenoid is potentially locked [POT LOCK SOL]. It is giving the warning for solenoid valve driver #2. The solenoid with the issue is on the C4 connector(?) located at 11 and 12. It must be reading the solenoid position from somewhere, so that would be the first thing to find out. Is it possible to see the sensor input for VALVE DRV#2 to see what values are showing?

"Pot lock solenoid" is the name of the output (solenoid) being controlled.

"Valve driver #2" is the name of the MC3

Basically this is an output error.

This error is showing up when the unit if first powered on, when there is no output being commanded to this solenoid.

When an output is commanded after power up the solenoid responds and no further errors are recorded.

This is an IQAN generated error... What I need answered is: What is this error supposed to mean and what is it trying to tell the end user? Normally when I've seen an output error in the past it is either an open load or overload error.

We replaced the module and the problem is resolved. Does a generic "error" always point to a hardware failure in the module?

Does the "replaced" unit that failed indicate errors when placed onto a different vehicle? It could be an error in the module (which would follow the module when in different vehicles), or it could be an error contributed too by the other parts in the original vehicle.


You can get this error status just showing "Error" on an IQAN-MC3 COUT if the CRET pins are shorted.

(shorting the CRET:s may show up as Error, Overload or Openload depending on which diagnostic measures that finds a fault first).

This wiring fault is detected when the COUT is activated, but not on startup.

There is only one other external factor I have seen that can give the IQAN-MC3 COUT the status "Error", when there is a command rapidly changing back and forth between active/inactive, the cycle time is minimal, and the dither frequency is high, it is possible to get this status. This one may also be reported as either of the statuses error, overload or openload.

The third possibility is an MC3 internal hardware fault on the COUT, detected by the startup tests. That seems to be the most probable explanation in this case.