MoTeC Global Forum

Hi all

Would I be right in thinking that the CDL3 sets the outputs to low (so to earth) when power is removed?

Does the ESDL3 exhibit the same behaviour?

Thanks in advance

The outputs of the dash are open collector with a 10k pullup to bat pos.

When the dash is not powered the outputs will be 'floating' and would not have a path to bat neg.

Very strange.

The Cartek PM-04, which controls the fans, turns the fans on when the CDL3 is powered off from the PDM.

Maybe it is just a Cartek PM-04 thing.

If an SDL3 (or any dash) isn't powered there is no continuity from the aux pins to bat neg.

It seems like your external devices switch inputs are not internally pulled high?

I would expect the same behaviour if the SDL3 wasn't connected at all as that is effectively what happens when it isn't powered on.

On second thought this sounds possible.

When the dash is powered off current will be flowing from the input pin of your Cartek device through the 10k pullup of the aux circuitry which ends up trying to power the 12v rail of the dash.

The current would be very low, maybe 1mA but it must be enough to switch the transistor.

Ideally the dash and Cartek device would be powered by the same circuit or at the same time to avoid this situation.

Thanks for the response. Seriously beginning to lose faith in Cartek products after this issue and my Isolator packing up!

I think you are right. The Cartek "PDM" will need powering from the Motec PDM to shut it off along with the CDL3/ESDL3...more wiring, yippee.

Technically the same circuit exists with a normal mechanical relay it's just you require significantly more current to switch it.