Falcon Electronic Speedo Conversion
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- เผยแพร่เมื่อ 21 ก.ค. 2020
- In this video I added a brushed DC motor to the back of the speedometer to drive the speedo/odometer. I am applying a PWM signal to the ground side of the DC motor to change it's speed which changes the position of the needle in the gauge. Using my MS3 ECU to apply the PWM duty based on measured vehicle speed from my rear mounted speed sensor on the differential yoke.
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Excellent idea! I was going to do a roller to gear mechanism off the CV joint (mid engine european trans). In my mind, the gears need to be 3d printed and easily interchanged so I can play with gear ratios until the desired RPM at speed is achieved. The trans I'm using has a HAL based speed sensor but I want to keep the mech speedo. I just love your idea. Cleaner, cheaper than a speedbox or a ECD200BT from dakotadigital, and lot less metal fab than making some sort of mech drive off the cv joint for sure. I already have a 3d printer so all I need to do is to design a base and adapter like you did and find a suitable 12v dc motor that will spin fast enough to match the max rpm of my mech speedo at 12v. Thank you sir!
One thing I later found out is as your car voltage moves about so does the calibration. I recommend using a 9v regulator or a buck/boost reg to give you a constant 12v to the motor. Depending on the amount of energy to spin your mechanical parts a 6v 300 series dc motor might do the trick. Glad I was able to spark an idea.
Hello!!! I was looking for some conversion mechanism for my Ford. I thought your project was really cool and I wanted to be able to do this conversion on my speedometer. Could you share your project so I can reproduce it here. My gearbox no longer has an electronic-only speedometer cable option.
I have a better conversion which uses a micro controller to read CAN data but could read a pulsed input for some other input. Email me at ryandenney347@gmail.com
can you share with us the electrical diagram of PWM controller? I have an 85 chevrolet c10 pickup cluster cable speedometer, but i change the transmission from 84 pickup, so the transmission sensor is electronic (2 pins), question, can i use this sensor with the PWM controller?
You plumb 12 volts into one side of the dc motor then the ecu switches the other side to ground as a PWM signal. The ecu has a 12 point curve you can adjust as VSS input to PWM duty output.
Put a diode across motor it will help make it smoother as well. Also a small cap will also smooth out the pwm. Might get much smoother readings at low pulse and every where else . Also if you give it more frequency it will be more stable as well
I did install a 1n4001 across the back but not the cap. I found some slightly smaller dc motors that I might try. This is just a proof that it could work.
Great start point for sure
So this is driven off your pcm's speedo output? I need something like this for a Cummins 5spd in a 56 dodge truck. I have a vss in the transmission but no place for a cable to hook up.
No, the ecu pwm's the low side of the dc motor. I tied one side on the motor to 12v switched power and the other side to the pwm output. Only issue is as the system voltage move around so does the calibration. Im using a generic output that i can adjust based on speed.
@@olboy1981 probably a stupid question but, is it essential pulsing the ground, the closer together the pulses the faster the motor spins?
@@jpfiero yep, thats exactly what's going on. Something like 10% duty is 8mph.. 25% is 20mph.. and so on. In the MS3 box we have a 8 point curve we can move around to get the proper mph reading vs duty.
@@olboy1981 very interesting thanks so much for the replies. I have no ecu (mechanical 12v Cummins 5spd) I only have a vss on my transmission. Could the vss be used to pulse a ground? I assume I would need to maybe vary voltage input to adjust speedo reading?
@@jpfiero no, the output signal from the vss is either a digital on/off at 50% duty or an analog sign wave. Best way to do this is to write code for a microprocessor to read the time between falling edges and then math your way to speed. Then sort a formula to go from speed to dc motor(speedo) rpm. You could close the loop on the speedo speed by measuring it and trimming the pwm to hit the proper target value. It can get quite complicated in a hurry. That Dakota digital unit does what I just described.
I wonder if this is possible to do on a ls swap with squarebody mechanical gauges ..... wouldn't have any clue would you? Problem with the squares is you can get a factory electronic speedometer from a 90-91 suburban but they are highly sought after and over priced.... this seems to be a cheaper alternative to that 🤔
You can buy a kit that does this, I think from dakota digital if you don't have time/ ability to build it. Would be great to come up with a cheap easy diy version though
th-cam.com/video/cMLg8IYF-Kw/w-d-xo.html
@@jpfiero pretty much.. big picture would be to grab vss from the ecu over CAN and then have a stepper motor or bldc to vary the speed to the cable drive. This would not care if the system voltage varied with electrical load.
Can you share the arduino code
send an email to ryandenney347 at gmail.