PWM cooling fan(s) control using ECM

[mikentosh]

Originally Posted by vannatta20

Anyone have any luck getting PWM output from an E38 ecu with a camaro OS? No matter what settings I use it will not output a signal. If I use a truck OS I get a PWM signal easily. The truck OS does not see AC pressure. The car OS does. This is why I need to use a car OS. I used an oscilloscope to verify

This would explain the same issue I was having earlier. I was also working with an E38 out of a Camaro. Would love to hear a response on this as we are running the setup with discrete fans on relays now and its annoying

Originally Posted by mikentosh

Wondering if anybody has troubleshooting advice for the PWM signal coming from an E38 ECU? I'm not seeing any PWM signal coming out from X1 pin 58.

I took my multimeter and put black probe to DkGrn wire coming from X1 pin 58, and red probe to battery positive terminal, and set to DC volts. Turning key on I can see the voltage go up to about 1.2V but regardless of toggling fans and duty cycle in HP Tuners I don't see any change. I would expect to see either ~5V or ~12V across here but do not. I didn't even bother to switch my multimeter over to duty cycle measurement, but assumed without the higher voltage its not working.

Any ideas on further troubleshooting? Pin 58 is a ground PWM signal correct?