Help with Gretz GA-1000 Pitot Control Module

Hello everyone! My Gretz pitot heat isn't working. I'm a pilot, not a builder, so my electronics knowledge is lacking and I'm hoping someone can point me in the right direction.

With the heat switch on, I'm getting voltage at 12+/12-, but not at P+/P-. It was working until recently. The LED temperature indicator lights still work when the pitot heat switch is turned on. Does that indicate a problem with the control module? Should I just buy and install a new one, or is there a way to repair the CM?

Any input would be much appreciated!

The gretz has a thermistor (i.e. temp sensor) in the probe. Don't know the details of the logic used on their board, but I would not expect the controller to send power to the probe with a probe (i.e. ambient) temperature of > 80*.

I would soak the probe in ice for 30 minutes and then turn on the switch. With the probe at 40*, it should send 12V to the probe leads. If that doesn't work, I would be checking for voltage on the coil leads of the relay. It uses the relay to let the low current logic power to switch the high current power to the probe. Possible the relay failed.

Larry

Larry, I love this answer and hope our recent high OATs are the culprit-that would be way too easy! Thanks for your input. I’ll check it out tomorrow and report back soon.

Jesse

Larry, you were right...it was just too **** hot for the pitot heat to turn on. This was a good learning experience for me - thanks for the help!