I am trying to figure out if it is possible to use an Arduino board in order to test that a wire harness has been wired correctly to a 48VDC fan that has positive, negative, pwm, and tach. control. I believe this can be done by simply sending the signals to all wires and returning a pass or fail. I am not trying to power the fans simply want to make sure that the wire harness has all Molex plugs seated correctly as a plug and play test for the fans before they get connected to the 48VDC board which can short the fans if the wires are in the wrong slot of the Molex plug.
"a wire harness" = vague description. To answer your question, requires details. Schematics, wiring diagram, specifications of the fan...
Let's take the wire harness out of the picture and just say from the fan itself using the red, black, yellow and blue.
Have you examined the impedances there to see how connections would be verified? As in, manually with a DMM?
A canonical test is to take the combinatorial impedance, for example between AB AC AD then BC BD and CD. In your case, because reverse polarity might damage some fan connections, you are limited in that respect. You have to expect every possible mis-wiring. So some good current limiting is required.
Actually, does your harness include the fan? Can the wiring be tested separately from the fan? Are you trying to identify shorts and opens, in addition to cross wiring? Pass/fail, or with an analysis?
The harness does include the fan, but can be tested without it. Not trying to identify shorts only cross wiring with a simple pass/fail. I would preferably like to leave the fan connected because production sometimes puts the wrong wire into the Molex connector.
Then goto reply #5.
Thank you for your help.
It's not possible to offer a good solution for this without the information I asked for. Metering the fan would be the very first thing I would do, because those measurements are required in order to identify the connections if they're not necessarily in order. As I can not be there to perform those measurements, I am asking you to do it.
The published specifications of the fan are not enough, because those only apply to the operation of the fan when it is properly connected and powered.