Hi everyone, I have a 1992 petrol peugeot 106 nx 1.0 liters without an ECU so I´ve been thinking of making one myself.
The first thing I´m going to do is to get a rpm reading.
Now, the thing is that I think the car has a sensor but I´m not sure .
I affirm this since there´s a plug with 3 connections (red,green,black) that apparently goes straight to the crankshaft.
My problem is that I don´t know what kind of sensor it is , how to read the signal, what´s the voltage I should apply or even if its a sensor .
I wasn´t able to find a part number since the motor is kinda of old and leaky.
I´m going to try to take a picture tomorrow and I´ll post it here.
Can anyone help me or give me some guidelines or useful links to help me with figuring this out?

Best Regards,
Carlos Almeida.

 

Hey Carlos. Without seeing what you have, I can tell you that three wire crank sensors are Hall Effect sensors.They generally have a 5 volt reference wire, a signal wire and a ground. They are best tested with an oscilloscope.
is this the original motor from the car?

 

Hi, sorry for the long wait, I was only able to get to the sensor today and I couldn´t get any info from it since its old and full of dirt.
Yes the motor is 100% original, the only thing I had replaced was the head gasket.
I followed your advice and tested it with a 5 volt reference. I don´t have a oscilloscope but I tested with a multimeter and got zero volts.
I mean with higher revs the time where the signal is at zero volts decreases so with higher revs the average voltage should be higher right?
But with higher revs the signal is still at 0V.
Since the car is old , maybe the sensor works at 12 V?
tomorrow im going to do a Diode test to see if maybe the pins are shorted.

 

Are you applying a turning toothed wheel rotating past the pickup part of the sensor? Without that the sensor output will be zero. The sensor internally is like a on/off switch, with the teeth moving past it turning it on and off.

 

Yes, I think that the sensor is applied to the inertia wheel in the crankshaft since it has been there since the car first rolled out of the production line so it should be able to pick up the rotation of the wheel.
I did a Diode test and the signal wire wasnt shorted to the positive or the ground rails. I got 204mV but since the car is old I assumed that the diode( if there´s one) is made out of germanium so its not that weird.
Is there an equivalent circuit for a hall effect sensor?
I powered it up to 12V and it didn´t Explode but the signal wire gave the same value as the reference wire

 

Are ther any part numbers on the sensor? Can you post a picture? Was there a mating connector on the car? Did you measure the voltages on it?

 

I powered it up to 12V and it didn´t Explode

Most outputs and inputs to senors are based on the ECM's 5V not 12V.