All CHT and EGT readings going whacko

[lenene]

On initial power up, all six readings are same as OAT. If I turn on strobe lights, they all immediately go to -99. Turning off strobes doesn't help, but recycle power to EMS fixes it. Totally separating strobe wiring from all other harnesses and trying again does not help. On a few occasions, flexing the wire harnesses also gives me -99. Is there a common thread that would cause ALL indications to go -99? Such as an interrupted ground? Nothing is noted on VMtr or AMMtr like a power surge or ??. Help??

 

[Dynon]

Which EMS product is it? A few things you can try to troubleshoot:

Disconnect the D37 (if this is not an EFIS-D10 or EMS-D120) before you turn on the strobes. Does that change anything? Same for the D25. Once it happens, does disconnecting / reconnecting either of those harnesses change anything?

 

[lenene]

sorry- Should have mentioned D-180 on Jabiru 3300 installed in Arion Lightning. Bought used recently and owner lost all docs and schematics, but I have downloaded all Dynon manuals, etc.
Thanks for the connector disconnecting tips. I will try when I get home next week.... GA

 

[lenene]

per your advice, I did disconnect the D37 and the CHT/EGTs all began reading ambient OAT correctly. Connecting back up restores the false -99 indications across all 6 cyls.
I suspect I have connected the spare grounds from the D37 to places not needed when they should not be. What say you?
Is it correct that the only inputs of power/ground required for operation is the "master power", pin 1 and the "master ground", pin 3 of the D25 connector and all the other ground pins are just furnishing convenient grounds for other sensors?
This is D180 just upgraded to 5.5 firmware with no problem.
This constant -99 readings of the CHT/EGT has been a bugaboo and I appreciate the help. thanks

 

[dynonsupport]

Yes, only pin 1 of the D25 needs to be grounded.

Just to check, you unplugged the D37, left the D25 connected, and booted on battery and all was OK? Not that you disconnected the D25?

That does sound like you are grounding something you shouldn't, like the 5V connector. Connecting ground to ground shouldn't hurt.

 

[lenene]

Don't you mean pin 3 of the D25 needs to be grounded. Pin 1 would be the 12V plus power. Correct? Or did you mean ONLY ONE pin needs to be grounded?
Yes, I had it all powered up with the CHT/EGT all reading
-99 and when I disconnected the D37, all the CHT/EGTs read correctly. Reconnecting the D37 caused them all to go to -99. The D25 was never disconnected. thanks

 

[lenene]

further to my problem- the 5v wire is disconnected and I disconnected or cut all the wires not going anywhere such as the extra grounds, and only have the actual sensor inputs still going to D37, and still have the problem with the CHT/EGTs. As long as D37 is disconnected, the CHTs are fine and accurate. Wiggling all wires looking for a break somewhere has yielded nothing.
Here is a clue. Killing ships power and letting the unit die out on its own 30 seconds of internal power allows the CHT/EGTs to read correctly????
Got any ideas? thanks :-?

 

[dynonsupport]

George:

Plug in the 37-pin connector and disconnect wires one at a time until the problem ceases. Then you've narrowed down the offending connection.

The "killing ship's power, it works normal" clue means that you're putting ship's power or some other voltage INTO the 37-pin connector of the FlightDEK-D180.

further to my problem- the 5v wire is disconnected and I disconnected or cut all the wires not going anywhere such as the extra grounds, and only have the actual sensor inputs still going to D37, and still have the problem with the CHT/EGTs. As long as D37 is disconnected, the CHTs are fine and accurate. Wiggling all wires looking for a break somewhere has yielded nothing.
Here is a clue. Killing ships power and letting the unit die out on its own 30 seconds of internal power allows the CHT/EGTs to read correctly????
Got any ideas? thanks :-?

 

[lenene]

Since turning off the master switch and letting the D180 run on internal battery allowed the CHT/EGT to read normal, I disconnected everything on the master switch one at a time and discovered that killing the power going to the fuel capacitance units gave normal CHT readings. I have no idea how this occurs, nor am I sure this is the final solution.

 

[dynonsupport]

George:

If "fuel capacitance units" means Dynon Avionics Capacitance To Voltage Converter, our guidance in the FlightDEK-D180 Installation Guide for installation of the Dynon Capacitance To Voltage Converter (Appendix F, Page 9-35) is that the Capacitance To Voltage Converter should be powered by the FlightDEK-D180, not master power.

We provide a 12V output to power sensors (ONLY sensors) such as this on Pin 15 of the 37-pin connector. This is the Red wire bundled with the White and Black wire. Pin 15 is also used to power the Fuel Flow sensor, and it's acceptable to use Pin 15 to power both the fuel flow sensor and the Capacitance To Voltage Converter(s).

Since turning off the master switch and letting the D180 run on internal battery allowed the CHT/EGT to read normal, I disconnected everything on the master switch one at a time and discovered that killing the power going to the fuel capacitance units gave normal CHT readings. I have no idea how this occurs, nor am I sure this is the final solution.

 

[lenene]

No, I was talking about the capacitance fuel measuring units in the wing tanks. 12V+ (formerly from the master switch) and a ground is furnished to them and they supply a signal voltage (0 to 5V or so) to the D180, pins 20 and 21, which is read out on the display as L and R fuel qntys. That's how I think it is supposed to work, however how this affected my CHT/EGTs I am mystified. I need to find some other source of 12V power for the fuel gauge system, apart from the master switch since that configuration affected my D180.

 

[dynonsupport]

George,
Our guess is that one of your senders is putting out far more than 5V. If you put too much voltage into one of our inputs, it can affect other inputs as well.

Are your fuel level readings accurate when the senders are powered on?

What brand are your capacitance to voltage converters for your tanks?

 

[lenene]

My fuel indicator capacitance probes are Princeton brand. One side is working perfectly and the other not. I may have fixed my problem by moving the fuel indicator sensor grounds to a common point with the other units in the plane as opposed to convenient airframe metal point. I think the erroneous side was putting out about 8 volts back to the D180.
thanks for your help....

 

[brianscoff]

Recently installed D120 in a Lancair 360, IO360 Lycoming.
All CHT, & EGT read -99.
Sent original unit back, bench tested ok, Dynon sent another unit, great service !
However, this one still reads -99.
CHT & EGT read fine sometimes, then go back to -99.
Has anyone else had this problem ?
I have checked all the plugs, pins, connections etc.
Any advise is greatly appreciated.

Brianscoff

 

[dynonsupport]

Brianscoff:

We suggest you get in touch with our Tech Support team directly to let them know that the replacement unit didn't fix the problem. If it checked out here and even sent a different unit, there's absolutely something going on with the wiring. The leading candidates are shorted or otherwise mis-connected 5V (pin 18) or 12V (pin 15) on the D37 connector.

Recently installed D120 in a Lancair 360, IO360 Lycoming.
All CHT, & EGT read -99.
Sent original unit back, bench tested ok, Dynon sent another unit, great service !
However, this one still reads -99.
CHT & EGT read fine sometimes, then go back to -99.
Has anyone else had this problem ?
I have checked all the plugs, pins, connections etc.
Any advise is greatly appreciated.

Brianscoff