CHT 3 no reading

[RNB]

So my number three CHT is not reading. Things are opened up so I changed the number three probe and powered things up, still nothing. I left the system on and wiggled the firewall forward wires, searched for a short. Nothing.

I guess I need to open the panel up and see if things are loose in there, maybe even get on my back.

Any pointers?

Advanced flight 5600 efis, no advanced module

Thanks

 

[RNB]

Never mind in a solution but help out with understanding. I started disconnecting other probes to see if some wires were crossed. When I disconnected my new CHT probe number three I was surprised to see my EGT temperatures disappear so I wondered if maybe there was a misunderstanding on my part or I didn’t understand which probe does which or if they’re comparing things mathematically I ended up replacing what I thought was the egt probe and now all my readings are good so in this photo the top left wires are for my bottom spark plug and then to the right is the probe that I expect is for EGT and then underneath the cylinder is the probe that I think is for CHT

Why did I need to replace the probe that I think of as being exhaust gas temperature to get a CHT reading?

 

[Auburntsts]

You are correct. In that pic the CHT is below the spark plug and the EGT is on the right. If you think logically about this for a sec you would expect the EGT to be the probe in the exhaust. That said I’m not sure why what you did fixed the issue although it sounds like it was a wiring problem that you resolved in the process of replacing both probes. Of course you might have had both probes go bad together. You could swap the old probes back in one at a time and see if the problem reoccurs then you know it was the probe and not the wiring.

 

[D-Dubya]

That sounds kinda wonky, but at least you're getting readings now. Rather than unwiring things that are now working, I would suggest you get a hair dryer or similar heat source and blow some heat on and around each of the eight CHT/EGT sensors (one at a time) and watch your display to make sure the correct cylinder's temperature starts climbing when the dryer is blowing on it. It only needs to climb a few degrees to confirm it's working. This will not only confirm the individual sensors are working, but will also confirm that they're going to the correct cylinder.