80s OE sensors with Motec M150

Hi all,

I'd like to retain some of the original sensors on my EFI/ITB converted 1983 Ferrari 512 BBi. One of which is the original vehicle speed sensor that feeds the speedometer (pic attached). Are there any suggestions on how to get this OE sensor to work with the M150? Ideally, I'd split the signal to the dash and the ECU. However, I wouldn't be opposed to sending solely to the ECU, then sending a new calibrated signal to the dash from the ECU.

Thanks in advance,

Robert

If it's a 2 wire sensor used for speed sensing then I would guess it's just a variable reluctor sensor.

If that is the case you should be able to wire it to UDIG input and sensor 0v.

The polarity will just define the signal waveform whether it rises or falls as the tooth passes.

Oh, good point. I actually use a UDIG with the OE distributor reluctance sensor. I'll try that.

What about something like an old oil pressure or oil temp sensor? Would AV and/or AT inputs work for those?

Tentatively yes, there most likely will not be a calibration for them so you would need to have that done. Some of the older single wire sensors are not recommended for use as they are very inconsistent in their behavior as they rely on the engine grounds to complete the circuit back to the ECU, so they can get noise and other errors induced from this.

Hey guys,

Getting back to this after taking a break to work on other projects. The factory wiring for this sensor is 12v from the fuse box, with the other wire going straight to the speedometer / odometer. So I'm guessing the UDIG/0V option above isn't going to work. Any thoughts? Maybe a Half Bridge for the 12v and a UDIG for the "signal"?

If I had to guess it's hall effect the bat +ve powers the internal circuitry, the other wire is the signal to the cluster which would be pulled high and goes low when a tooth goes past and the ground is through the sensor body?

It is a reed switch, it just shorts the two pins together when a magnet goes past the end. Just connect the ecu digital input to the same wire that goes to the speedo. Leave the pull-up in the ecu turned off.

http://www.dinoplex.org/instruments/vegliaspeedosensor/index.html

Here's a good article showing the guts of this sensor. Not hall effect like I guessed.

So Adam would be right splice the output signal into a UDIG.