Analogue to Digital converter

[Gibbon]

Howdy

I am looking to hook up the speed sensor from a MA61(*) to the digital input on an Adaptronic ECU.

Google tells me this:

"The factory dashes SPD output is a 4 pulse per rev of the speedo cable to EARTH.
Its the same signal that goes to the Cruise ECU. (and PPS ecu and ECT ecu if your car has those)."

The Adaptronic manual tells me this:

These signals are input to the ECU as digital signals. For inductive wheel speed sensors (such as many ABS sensors), you will need some simple external circuitry to convert the analogue signal into a digital pulsed signal that the e420c can use,

So I rang Jaycar to be told they don't sell such a thing. Does anyone know where such simple circuitry can be found?

I am not in any way an electronics guy so would have no idea on how to build one from scratch.

Thanks

(*) - I am tapping into the speed sensor terminal located in the working cruise control computer.

[RA35GT]

That terminology is confusing.

The factory speedo going to earth is still digital (uses a reed switch), but its not a complete square wave. I.e. its either earth or open circuit instead of changing between earth and a voltage.

The inductive ABS sensors are different again in that they are a sinusoidal type signal, speed is still related to the frequency and not the voltage level though.


If the cruise computer speed input is just the one from the dash which goes to earth. You should be able to use it directly from that wire with no other components.

1.5. Vehicle Speed Sensors (16-pin cable, brown and orange)
This is used for idle speed control on vehicles which have no neutral switch, however
they can also be logged by the PC.
· These inputs have a passive pull-up, and therefore a sensor that shorts to
ground (for example, Hall Effect, optical or reed switch) will be suitable.

[Gibbon]

If the cruise computer speed input is just the one from the dash which goes to earth. You should be able to use it directly from that wire with no other components.

Already done that - and I'm not getting any signal. I clicked the Learn 50km button, and it changed the value within the application from it's default value of 4300 to 5 - but I'm not getting any MVSS data - it always says 0.

The manual also says:
If the ECU receives no pulses in a one second period, the speed for that input is set to zero

So - set to zero from then on - or just that cycle?

Thanks.

[RA35GT]

Which version of firmware are you using? There were issues with the learn speed function which was only fixed recently.

You can try to change the numbers manually also to see if you get any values for the speed.

Otherwise make sure the speed input is wired into the correct wire. You can also try the SVSS input to double check.

[wilbo666]

Firstly you don't need or want an ADC (Anlogue to Digital Converter)!

And secondly the factory SPD signal from the dash is fine.

Already done that - and I'm not getting any signal. I clicked the Learn 50km button, and it changed the value within the application from it's default value of 4300 to 5 - but I'm not getting any MVSS data - it always says 0.

Sounds like you have no speed pulse reading that description...

The manual also says:
If the ECU receives no pulses in a one second period, the speed for that input is set to zero

So - set to zero from then on - or just that cycle?

Thanks.

The manual is just explaining that after 1 second of no pulses the speed is set to zero. So when you go so slow as to only get 1 pulse per second the MVSS value will be set to zero.

Also imagine coming to a quick stop - the ECU counts the pulses over a period of time, if you stop suddenly it's likely to be incorrect and might show a value for a short time after you stop... but after 1 second of being stopped it's guaranteed to read zero

But as soon as you have pulses again the MVSS signal will read again!

Which version of firmware are you using? There were issues with the learn speed function which was only fixed recently.

You can try to change the numbers manually also to see if you get any values for the speed.

I'm pretty sure that the problem was with the "Learn Gear" functions as far as I'm aware, and not the learn 50kph function, but it is something you can try

Otherwise make sure the speed input is wired into the correct wire. You can also try the SVSS input to double check.

I also suspect that you have an issue with the wiring / sourcing of speed sensor signal from the car!

You should be able to pick up the speed sensor signal in the passenger foot well on the Cruise control plug, and as said it should connect to ground 4 times a revolution of the speedo cable... you should be able to check this with a multimeter and a friend turning a wheel / speedo cable

I think the below image is correct for Aus MA61, but I haven't checked myself...

http://www.cygnusx1.net/Supra/Librar...ection=BE&P=70


Cheers
Wilbo

[RA35GT]

I'm pretty sure that the problem was with the "Learn Gear" functions as far as I'm aware, and not the learn 50kph function, but it is something you can try

Oh crap, I think you're right.

[Gibbon]

Firmware + software is version 9.

Yes - that's the pic I used - tapped the wire into terminal 6 - Speed Sensor. I'll double check the wiring and also try it with the SVSS as well.

Cheers

[Gibbon]

Fixed !!! - Always remember to get the terminal numbers from the connection - not the plug

The Tacho is only thing that's not working now - any ideas?

FYI: If the tacho worked with the stock ECU then that would mean that you already have a tacho booster installed somewhere, which I would have thought might have been easy to see?

Cheers
Wilbo

After reading about tacho boosters from the search engine, and saw that some are made by using an old relay - I remembered this:



and



It has four plugs - IN, T, 12v and what looks like an E.

12v is powered from the ECU +12v

IN is joined with a wire that goes to the fan control unit and off into the loom.

T goes off into the engine bay, but appears to be a newer wire. It runs off into a connector near the fuse box.

E looks like the original wire running off into the loom somewhere.

How would I find out if this is a sideshow installed tacho booster?

EDIT: Hooking up the IG- to Coil1 results in a tacho that reads way to low. Using Aux out from the adaptronic says it needs a pull-up.

Cheers

[RA35GT]

Use an Aux out set as tacho. (do not need a pull up resistor). Remove the contacts within the relay, ticking will drive you nuts.

[wilbo666]

Fixed !!! - Always remember to get the terminal numbers from the connection - not the plug

Pin numbers works either way (Plug or socket) You just need to remember that female starts from top left and male top right

The Tacho is only thing that's not working now - any ideas?

This hasn't been working for ages

You need to get a multimeter out and start tracing wires! If you think that "relay" is a tacho booster then get the multimeter out and trace to the dash tacho input... if it goes there then it's a good start If it does then you can trace the other wires going to it (power, gnd and tacho in signal...)



Cheers
Wilbo

[Gibbon]

Use an Aux out set as tacho. (do not need a pull up resistor). Remove the contacts within the relay, ticking will drive you nuts.

Works !!! I have a tacho again. Thank you for your help.