Lane B Engine ECU Nominal Current not reached.

Be sure to log every removal and reinstallation of an ECU connector in the aircraft maintenance records.  Those three connectors are life-limited to a maximum of 25 mating/de-mating cycles.

Rob,

You might find this drawing helpful.  It was posted here a while backs and it looks like an actual Rotax document.  For the B connector on the ECU pay attention to pin M2 for the problem you are seeing.  That’s the pin that delivers the (-) signal to coil 3T/4T.  The power (+) comes from the fusebox. Also, Rotax recommends a product called Deoxit be used on the ECU connectors if cleaning is needed.  Other electrical connectors on the engine and fusebox are approved for use with dielectric silicon grease, but not the ECU.

Quote (Jeff B): "Also, Rotax recommends a product called Deoxit be used on the ECU connectors if cleaning is needed. Other electrical connectors on the engine and fusebox are approved for use with dielectric silicon grease, but not the ECU."

Jeff, can you point me to the source document for these recommendations?  Thanks!

Hi Eric

See the 912iS MMH, section 76-50-00, page 17. There is a note in the upper right of the page.  I have attached the page below.  Deoxit is about improving the quality of the contact surface. It’s used a lot in electronics (and electric guitars) where it is applied to very low current and low voltage devices to improve and preserve the contact surface. The ECU is similar, with some sensors and devices operating at low voltage and current, requiring very low resistance connections.  

Dielectric grease is an insulator, and it works because the connector friction displaces the grease at the contact point, leaving the remaining grease around it to stop oxidation and arcing.  I know some have used dielectric grease on the ECU connectors with success, but with the properties of these particular connectors dielectric grease may in fact worsen the connection.  

I have pulled and reset the B plug on the ECU.   I was able to get a good look at it, and I didn't see anything untoward.  It almost seems random if it starts up with a fault.  Today, after performing the 100 hour inspection, It initially showed a fault, but cleared when cycled the B lane.  I did a couple of laps in the pattern, and on downwind on the second lap it faulted again. Wiggling the connector while it was running didn't seem to do anything.  I'm suspicious that its not the connector.
I'm going to try to find help from Midwest Sky Sports where I was last fall.
Also looking through the service instruction that you provided, I think I allready have the new hardware.  It doesn't match what is in the maintenance manual (older date), and matches the service instruction.