Adding extra engine sensors to a GEA24 and using Rotax FADEC query

As far as I know you can’t add sensor inputs directly to the Rotax display CAN bus.  But there are inputs for all four CHT sensors at the GEA24. So you could wire the other CHT sensors directly to the GEA-24 and they would be displayed on the G3X GDU460 alongside the Rotax Display CAN info and look the same. 

You need to look at the G3X installation manual, specifically the “LRU Pinout” section for the GEA-24.  Somewhere around page 23-24 of section 23. The existing Rotax sensor is located on cylinder 4, (even though it does not use the physical CHT4 input on the GEA-24). So for the new sensors you would use the GEA-24 inputs for CHT1, CHT2, CHT3. Then you have to configure those inputs in the GDU460 configuration mode.  Those new inputs will need to be configured for the sensors you choose, which is different from how existing CHT sensor is configured since it comes over the Rotax Display CAN.  More specifically, that existing sensor is configured as “Rotax FADEC”, whereas for your new inputs you will configure them for the sensors type. 

Apologies Jeff,

Some poor wording in my original post, intention was to not try and add the extra sensors to the Rotax ECU or via the CAN/FADEC data bus, instead wanted to plug in extra sensors connected to the Garmin GEA 24. Was hoping to find someone who is using the FADEC sensors for CHT on the G3X and added some more via the GEA24.

One  issue I have found is the 915iS uses on cylinder four a temp sensor (Part number 965537) And for consistency the plan was to add three more of the same type sensors, the GEA 24 supports a few different temp sensors types:

1. Rotax 966370 (Type K thermocouple)
2. Type J thermocouple

3. Thermistor (VDO or 50-150 °C Thermistor)

4. Rotax 965531 (look to be the sensor used on the 912 engines, think these are NTC)

5. Rotax 966385 (look to be a PT100 type sensor)

So connecting the extra 965537 style sensors may not even be able to be used on the GEA24. I need to confirm what type of sensor this actually is or swap it for another type that is known to work with the GEA24, I suspect when measured it may by an NTC thermistor, but need to confirm before changing from a 965537 style sensor to another type, need to check diameter, thread and length of the temp probe is compatible with the 915iS cylinder head sensor port.

One nice part of the 965537 style sensors (apart from the price!) is the nice weatherproof moulded connector it uses for the wiring harness and its known to be compatible with the port on the 915iS cylinder head.

Regards,

Byron.

This is sold as a replacement for the 912 ULS sensor. I don’t know for sure but I would think rotax uses the same thread (10mm x 1,5) for all of its engines - that would be easy to verify. And I agree, these are likely NTC.   I do like the connector on the 965537 but the Faston connector would be fine for the other three sensors.  This would be low cost to try.

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