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CANBus Communications Decoded

Relevant Module: Worked Examples > Network Setup - Using a Device as a Gateway > Step 4: Program Devices to Transmit Required Data

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hello, my doubt, can I simply disconnect the sensor and place the potentiometer in the connector that goes to the ECU, and which pins do I place the potentiometer, and which one to use? Is 10K good?


Hi Richard,

The potentiometer example is used to show how you can make a transmitted value change without having to actually influence the operation of the engine at all.

Take manifold pressure as an example, it would be difficult to determine where this is if the engine was running as it likely closely corresponds to throttle position and many other values. If you replace the manifold pressure sensor with a variable potentiometer you can 'trick' the ECU into seeing a different manifold pressure reading which is then transmitted to other devices on the bus.

Replacing the sensor with a variable potentiometer allows you to change the manifold pressure value transmitted while the engine is not running. If you have access to a workshop scan tool you can also set it to a specific value to then correlate to the data you are seeing with your CAN interface.

The potentiometer should have supply V, 0V and output pins. to ensure you pin it correctly to the vehicle you would need to know the pin orientation of the sensor you are replacing. The resistance range of the potentiometer should suit the sensor you are replacing.

My objective is to find the CAN of the SONDA LAMBDA, without starting the engine I would like to put a potentiometer, so that I can vary and identify the CAN of the Lambda. My question is what is the connection of the potentiometer in the connector that would go to the lambda sensor.

Now in the connector where the bosch 4.9 sensor would go, should I connect the signal to the nernst(6) cell pin, the power to pin 1 and 0V to pin 2?

It's to send to my MOTEC Dash, which in turn will send the MOTEC M150 ECU.

Are you using a MoTeC LTC or an older monochrome dash with onboard lambda sensing functionality?

There might be an easier method to find the CAN data you are looking for.

I use Plex Knock V3 and REALDASH.

the lambda is original to the car, I want to check if it is possible to find it in the CAN.

I use Plex Knock V3 and REALDASH to view the CAN NETWORK

I don't think you can use a potentiometer on an O2 sensor input. It is too "processed" by a controller before the data is delivered on the CAN bus.

But the lambda sensor is not simple like a pressure sensor, so I don't know if it's possible and which pins I should use

Sorry if I was not clear YOU CAN NOT USE THE POTIOMETER TECHNIQUE for an O2 Sensor.

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