I have my Fluke DMM hooked up to pin #23 and chassis ground. When the engine was on (idle) I got about 50Hz. It would fluctuate a lot and seemed to increase as I pressed the gas but it didn't seem to be linear and certainly not respective of the actual engine RPM. I was able to get the squirt hack working but the RPM one I wasn't successful with. Can someone guide me in the right direction?
I would suggest you to subscribe the techinfo.toyota.com site (starting US$15/2-days) for obtaining wiring diagrams, repair manuals and others. Ken@Japan
I have the schematics. I can see where the IGF wire goes to and from. I can measure frequency. My only issue is that the value doesn't seem to be correct. I seems too low. For example, at idle, I'm measuring about 50 Hz. When I multiply this by four, that's only 200Hz or 200 RPM. Wouldn't a DMM be the most accurate tool to measure frequency?
Yes, I'm an idiot. The engine speed is rpM, not rpS! Thanks for helping me on that. But, how did you come up with 200Hz = 1200 RPM? Wouldn't that be 12,000 not 1200?
Ahhhh, you just turned my light bulb on! ........in a non-sexual way of course.....haha! I was multiplying by 4! So yeah, I was seeing about 50Hz, which is about 750 RPM at idle. That seems about right! Now I just have to hook it back up to my PIC and redo the math and I should be good! Thanks for the help Ken!
50 Hz X 60 = 3000 3000/4 = 750 My confusion was that I was multiplying the IGF pulses by 4 when I should have been dividing by 4.
Anyway... On highway driving (above 42mph), you should observe approx 1000rpm when it is fuel-cut mode (accelerator off), and you should observe approx 1300rpm on the minimum power demand. Please do calibration of your tacho-meter using above known rpm numbers. Ken@Japan
I checked this last night. I need to condition the signal a bit through software or by using a capacitor but I see between 980 - 1040 RPM in SHM and when the Prius is in regen (above 41, gas not pushed), I see between 1200 and 1400 RPM(my value jumps a lot) At idle, with the engine warmed up, I see about 800 RPM, give or take 100 RPM. Do these numbers seem about right?
These numbers are same as my observation. My observed warming up number is between 1200-1350 rpm. I have never seen below 950 rpm when engine was running. Ken@Japan
Here is a record of RPM, speed, and HV current from this morning that agrees well with Ken's numbers:
