mosfet

[jpanhalt]

You really do need to give us more information. How many pulses per revolution does your drive train give? How big are your tires? What is the rear end ratio?

I doubt the drive shaft gives just one pulse per revolution, but assuming it is just one (1), then 6800 pulses per minute = 6800 rpm. If the rear end is 4:1 (I know that would be very unusual), then the tires are rotating at 6800/4 or 1700 rpm. Now, if you have a common 14" tire, the rolling circumference is 66" (**broken link removed**). 66x1700/12 = 9350 feet/minute = 156 feet/second = 106 mph. Obviously, that is not 10 mph. Something is wrong. Even if the final drive (before differential) is giving 4 pulses per revolution, it is still a lot more than 10 mph.

How about giving us some real data to work with to help troubleshoot this problem?

JOhn

 

[LERMACHINE]

The transmission will generate twelve pulses per revolution of the "output" shaft. I can get all of the gear ratios and tire data you want but I don't see how this will help. The drill was only used to excite the sensor which I determined was working because the ecu is showing a speed. (I tried spinning the tire with the sensor in the transmission but could only get 1-2mph before the limited slip would lock up, preventing me from spinning the wheel at all) I ran a test on the digidash today(with its software) that supposed to allow you to do a sensor check. Now I would assume if my circuit is grounding the signal wire when on it would at least show it's receiving a signal. What other data would you like?

 

[ronv]

It is only a guess, but your cluster may have a small pull up resistor to +5 and the 10K in the source of your circuit may not pull it low enough. Try this one.
Not sure of what to make of the pulse count.

 

[jpanhalt]

The only reason for asking the gear ratios and tire sizes was to do a quick reality check on your observed indication of 10 mph at 6800 ppm. So, knowing the 12 pulses per revolution, that part checks to be OK.

I agree with ronv's suggestion. If it then stays off, reduce the turn-off resistor size for the mosfet.

John

 

[LERMACHINE]

It works!!!!! I duplicated ronv's diagram and its perfect. Thank you all again for your help! This beats spending $85 for a speed converter and taking the easy way out!