PWM radiator fan controller

[terrydmorgan]

Sorry John, but I don't have mine programmed yet. I'd put a scope on the output J3-49. In pwm mode, you should see a signal that varies with temperature/pressure. If not, then could be an ECU issue. If the signal does vary, then problem is likely with the fan controller.

For fun, I did a quickie re-wire with a relay, changed the ECM back to discrete, and the fan came on as it should.

That says the problem is either in the programming or in the fan controller. And since having both new fan controllers not work seems unlikely, I'm left with programming. But that's dead simple, see above.

Maybe both controllers are bad? Maybe that's why I got such a good deal on them?