Recent content by rufusthedog

I'm using a 210 on / 195 off thermostat for the fan but I haven't read the real temperature but I will hook up the code reader and get some real numbers. I did monitor the requested fan speed and hung around the the 600 RPM range.

The 555 timer would work but AtTiny85 is so cheap and doesn't require any external parts other than a 5V regulator. I decided the Occam's razor approach where the simplest solution is often the best and I didn't monitor anything and just sent out a fixed signal. If I went with PWM fan I would...

It has been over three weeks now and no CEL, I'm going to call it good to go.

That will be next option if lowering the RPM doesn't doesn't fix it. My thought is the RPM shouldn't change much if the electric fan doesn't get overwhelmed and can keep up with the cooling demand.

I think my main problem was I was sending out too high of a RPM response. I read the speed the computer was expecting and it was around 600 RPM and I originally was sending back over 4000. I cut it back to around 600 and I hasn't thrown a code for since and it has been over a week now and...

I played with again and read the data while is was plug-in and I had it way too high. I cut back the pulses and now it is reporting ~600 RPM. So far so good but I will have test it more.

FAIL#@%*. It did finally throw PO495 code. I will try to read the PWM control signal and vary the pulses accordingly.

It looked like the clutch fan put out 5 pulses per revolution so I picked 10 KHz(2000 RPM). I'm still testing to ensure the CEL stays out.

I went ahead and designed a little PCB and printed a little housing. I hooked it up today and I drove to the dump and so far it is keeping the CEL out. I'M thinking about expanding the design to read the temperature and control the fan to vary the fan speed instead on/off like it is now. Op

I knew about their PCM programming for free, I just didn't want be without my Saab for the time it would take to ship to NC from CA. I was also curious if would work or not.

I installed the pcmofnc Plug and Play kit this weekend. I didn't want to have to send out my PCM to get re-programmed and I didn't want to $250 for a PCM programmer so I took the harness off the old clutch fan and wrote a simple program for a $5 Arduino uno to test if I fake a pulse to the PCM...