Diagnosis of OAT failure

[pmerwood]

Hi

I'd appreciate any help diagnosing my OAT failure.

I have an EFIS-D10A installed with a type 2 OAT probe. It's functioned well and accurately for about 3 years but over the last few weeks it stubornly reports -25 degrees Celsius (-13 Fahrenheit).

I've checked all connections and can't find anything obviously wrong. The probe is connected through the EDC-10 remote compass and that's working ok. I've done the "headphone test" - the EFIS only records a compass swing when the headphones pass the EDC so that says to me the cabling between the EDC in the rear of the aircraft and EFIS is ok.

I suspect the probe may have failed. Any ideas or other checks I can perform?

 

[Dynon]

So the yellow and blue wires should measure a variable resistance. With power off, here are the rough numbers:

20C: 12.5K
30C: 8K
40C: 5K

...so your current reading of off-scale low could be the result of the probe just not being connected (wiring issue)

You should also see 10K between the red and yellow wires all the time.

 

[pmerwood]

Thanks for this info. I'll unplug the OAT from the EDC-D10 and make the measurements you've suggested.