MS3 w MS3x VSS, speedo output and EPAS control

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therealpinto
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MS3 w MS3x VSS, speedo output and EPAS control

Post by therealpinto »

Hi all

I have a 1974 MkII Capri running a turbo Pinto, T5 transmission and a rather fresh MS3 install with MS3X (car has ran MS1 extra since the early 2000's).

Now I want to add some VSS functions, main reason is that the current mechanical speedo is mismatched to the drive train and the mechanical speedo wire is hard to route.

I have bought a VW speed sensor (VW Sharan, seems to be the same on many others, 3 pin so hall effect I'd say) that I'm planning to fit to the gearbox using an adapter. According to the documentation I find, VW powers it with +12v on the outside pins and the signal is on the middle pin.

Is the hall effect sensor polarity sensitive? If so, can I determine the correct polarity by doing some measurements on the sensor?
The MS wants a 0-5 V signal (planning to use the PT4 input since datalog, launch and tableswitch are in use), is it likely that I can just power the sensor with 5V?

The next question is to run an electronic speedometer from the MS. I see that there is a dedicated VSS output function that probably works well. Does that output give a signal that goes to ground? I plan to use either a Volvo 240 electronic speedo or Ford Scorpio/Granada.

The third development is the addition of EPAS, electric power steering. I have a MGB EPAS on it's way, and I would like MS to provide the EPAS ecu with the correct signals if possible. The information I have is that it expects a 1000-3000 Hz signal for rpm and a 100-250 Hz signal for road speed. Can I use generic pwm outputs to do this? If so, how would I set them up?

I have to road test the EPAS to see how the amount of assistance refers to road speed, I suppose I would want it set up to give full assistance at 0 speed and up to say 10 km/h, then probably ramp down to 0 assistance pretty quickly.

Any input is appreciated on this.

Regards

Gustaf
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Matt Cramer
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Re: MS3 w MS3x VSS, speedo output and EPAS control

Post by Matt Cramer »

therealpinto wrote:Hi all

I have a 1974 MkII Capri running a turbo Pinto, T5 transmission and a rather fresh MS3 install with MS3X (car has ran MS1 extra since the early 2000's).

Now I want to add some VSS functions, main reason is that the current mechanical speedo is mismatched to the drive train and the mechanical speedo wire is hard to route.

I have bought a VW speed sensor (VW Sharan, seems to be the same on many others, 3 pin so hall effect I'd say) that I'm planning to fit to the gearbox using an adapter. According to the documentation I find, VW powers it with +12v on the outside pins and the signal is on the middle pin.

Is the hall effect sensor polarity sensitive? If so, can I determine the correct polarity by doing some measurements on the sensor?
The MS wants a 0-5 V signal (planning to use the PT4 input since datalog, launch and tableswitch are in use), is it likely that I can just power the sensor with 5V?
The power and ground will be polarity sensitive; check your wiring diagrams. (I know, that's not easy when they're factory VW diagrams. But that's the best way to check it.) For magnetic polarity sensitivity, only if it doesn't have a built in magnet. As for whether it will work with 5V power - most likely, but you'll have to test.
The next question is to run an electronic speedometer from the MS. I see that there is a dedicated VSS output function that probably works well. Does that output give a signal that goes to ground? I plan to use either a Volvo 240 electronic speedo or Ford Scorpio/Granada.
Depends on what output pin you use, but most pulse to ground.
The third development is the addition of EPAS, electric power steering. I have a MGB EPAS on it's way, and I would like MS to provide the EPAS ecu with the correct signals if possible. The information I have is that it expects a 1000-3000 Hz signal for rpm and a 100-250 Hz signal for road speed. Can I use generic pwm outputs to do this? If so, how would I set them up?
The PWM outputs do not adjust frequency. Maybe your regular tach and VSS outputs will work.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
Laminar
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Re: MS3 w MS3x VSS, speedo output and EPAS control

Post by Laminar »

The later T5 boxes on the V6 Mustangs came with the built-in VR speed sensor. Is the VW+adapter route easier than using the standard T5 sensor?
therealpinto
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Re: MS3 w MS3x VSS, speedo output and EPAS control

Post by therealpinto »

Thanks for the input!

I have unused spark and injector outputs so I plan to use that for the speedo, so pulsing to ground it is then. Should work with most speedos I guess?

As for the PWM outputs, what does the "Variable frequency" mean in the drop-down list for "Frequency/on-off"? The help box says;
Variable frequency - output runs at the frequency set by the table/curve with 50% duty.

I interpreted that as a possibility to output different frequencies but I may well have gotten it wrong.

Laminar, I'm in Sweden and Mustangs, especially V6 Mustangs, are not common. I use the rather rare Sierra Cosworth T5 so it's not easily swapped either (euro spec input and output shafts).

Regards

Gustaf
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Re: MS3 w MS3x VSS, speedo output and EPAS control

Post by Matt Cramer »

Forgot about that; it's a new feature. However, max frequency is 250 Hz, so this will work for speed but not RPM.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
therealpinto
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Re: MS3 w MS3x VSS, speedo output and EPAS control

Post by therealpinto »

OK, cool, so that would probably work then.

I'm not really sure how to setup the table/curve for outputting a frequency in relation to VVS input but I need to study the documentation more then.

The 1000-3000 Hz signal for rpm could probably be arranged with some kind of separate 555 timer I guess? Unless the ECU would accept a tacho out signal or similar.

Thanks

Gustaf
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Re: MS3 w MS3x VSS, speedo output and EPAS control

Post by dontz125 »

555s are great with PWM, not so much with variable frequency. What you can do is set up your output for PWM, feed it into an RC PWM to voltage circuit, then send that to a voltage to frequency converter chip. Not the most elegant, but it'll work.
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Re: MS3 w MS3x VSS, speedo output and EPAS control

Post by therealpinto »

Thanks!

As far as I know, I think the EPAS ECU mostly looks for an rpm signal to see that the engine is running. So I guess it could work with a fixed frequency that just makes it think the engine is running. I think the speed input is more vital.

I will try to set the stuff up and see what happens.

EPAS is quite popular in Europe to retrofit, EPAS control might be a nice option to consider in future development of MS3.

Gustaf
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therealpinto
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Re: MS3 w MS3x VSS, speedo output and EPAS control

Post by therealpinto »

Hi again

I'm getting closer but I have a bit of a hard time getting my head around how to connect the VSS sensor.

I have a hall effect sensor where the output switches to ground as I slowly turn the shaft. So how do I connect it to PT4? Signal wire to PT4 and a pull-up resistor to 5V on that line?

Sorry if it is basic but I have read the manual and a number of threads and still I'm not sure.

Thanks

Gustaf
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Re: MS3 w MS3x VSS, speedo output and EPAS control

Post by jsmcortina »

Just connect to PT4, there's an internal pullup.

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therealpinto
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Re: MS3 w MS3x VSS, speedo output and EPAS control

Post by therealpinto »

Thanks!

I don't get that to work though, there is no jumper or something to change? I will double check the connections and make a log as soon as I can.

Gustaf
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therealpinto
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Re: MS3 w MS3x VSS, speedo output and EPAS control

Post by therealpinto »

Update, a double check of everything and now the VVS input works fine.

I set Injector H as the speedo output and it operates (flashes a LED) but does not drive the speedo. Now, the speedo came from a scrapped car (Ford/Merkur Scorpio) so I am not sure if it is OK. This site: http://www.bitsprings.com/gearinst.pdf suggests that it wants a 20-200 Hz signal, but not very much more information.

Perhaps a pull-up resistor 12V would be worth a try?

Regards

Gustaf
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Re: MS3 w MS3x VSS, speedo output and EPAS control

Post by dontz125 »

The injector driver is a ground-switching input, and doesn't actually generate a voltage pulse. You definitely need a pull-up of some type, and most speedos are 12v.
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Re: MS3 w MS3x VSS, speedo output and EPAS control

Post by therealpinto »

Thanks, I see, of course.

I have seen both pull-up circuits with a transistor, and simple ones just using a resistor. Any specific one to prefer?

Gustaf
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Re: MS3 w MS3x VSS, speedo output and EPAS control

Post by dontz125 »

If we're talking about the same thing, the pull-up and a transistor circuit includes a coil to generate the flyback pulse that a tach driven off the coil -ve would expect. If the tach can be driven with a simple square 12v pulse, then all that's needed with the injector driver is a 1k pull-up to 12v.
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Re: MS3 w MS3x VSS, speedo output and EPAS control

Post by therealpinto »

Since the speedo is electronic it should just need a pulse. So I will try the 1k pullup and see how it fares.

Thanks a lot!

Gustaf
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Past projects:
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MS&EDIS/MS-extra
therealpinto
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Re: MS3 w MS3x VSS, speedo output and EPAS control

Post by therealpinto »

Success! With a 1 kohm pullup to 12V the Granada MkIII/Scorpio speedometer seems to work fine.

Thanks for all the help!

Gustaf
__________________________________
Ford Capri 2.0 Turbo
Past projects:
2.8 Twin turbo & 2.9 24v Twin turbo
MS&EDIS/MS-extra
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