Hey guys,
Got a couple of questions
I am trying to layout a the safe/cheapest circuit that would detect when a Fuel pump is running in a car. The fuel pump has a constant 12VDC and the ECU sends a GND signal to a relay that turns it on.
How can I have my Arduino detect a high signal when the pump is on. I know a voltage divider with a Zener diode will bring down the 12VDC to 5VDC. But the ECU outputs a GND signal. How would I wire this up?
The end goal here is to eliminate the fuel pump and have a arduino detect when the fuel pump is on.
Second question
The ECU has input switches you can turn off and on with a GND signal to the ECU input. You can also invert the ECU signal and connect it to 12VDC. I want to connect these signals together without using a relay. Looking for a safe/cheapest solution.
Third question
The ecu has a TPS sensor and would like to simulate it using a digital POT. The sensor operates 0v to 5v. Looking for a safe/cheapest solution to simulate it.
Thanks
I wonder about the feasibility of using current detector, possibly even non-invasive and would not matter if it is side on power or ground.
Where is said car located? In the US? Most cars I know of (in the US) have the fuel pump running all the time. There is a pressure regulator at the engine, that returns any fuel not needed to maintain fuel pressure to the tank. Some vehicles have a variable speed fuel pump instead of a pressure regulator. Either way when the car is running the fuel pump runs at some speed 100% of the time.
How are you planning on supplying fuel to the engine is you eliminate the fuel pump?
adwsystems:
I wonder about the feasibility of using current detector, possibly even non-invasive and would not matter if it is side on power or ground.
Where is said car located? In the US? Most cars I know of (in the US) have the fuel pump running all the time. There is a pressure regulator at the engine, that returns any fuel not needed to maintain fuel pressure to the tank. Some vehicles have a variable speed fuel pump instead of a pressure regulator. Either way when the car is running the fuel pump runs at some speed 100% of the time.
How are you planning on supplying fuel to the engine is you eliminate the fuel pump?
I am making a simulator and would like to detect these signals with a Mega
How can I have my Arduino detect a high signal when the pump is on. I know a voltage divider with a Zener diode will bring down the 12VDC to 5VDC. But the ECU outputs a GND signal. How would I wire this up?
The same way! 
(But, with reversed logic where 12V means is off.)
When the pump-ground is not connected to car-ground, the pump-ground wire should have 12V on it. Do you have a multimeter to check that? If you don't have a meter you can use an LED connected between car-ground an pump-ground (with the usual ~1K current-limiting resistor). The LED should be on when the pump is of
...The pump is like a bit 'ol pull-up resistor. With the ground open, the voltage is "going through" the pump but no current flowing and no voltage is "dropped" across the pump. When you ground it, you get a complete circuit so current can flow and you get 12V across the pump.
Any suggestion with the questions below
Second question
The ECU has input switches you can turn off and on with a GND signal to the ECU input. You can also invert the ECU signal and connect it to 12VDC. I want to connect these signals together without using a relay. Looking for a safe/cheapest solution.
Third question
The ecu has a TPS sensor and would like to simulate it using a digital POT. The sensor operates 0v to 5v. Looking for a safe/cheapest solution to simulate it.
Hi,
Where are you getting all this I/O information, rather than tell us can you show us the ECU and the equipment around it.
A hand drawn diagram of the ECU and the switches and inputs and outputs it has connected will help.
Can you please tell us your electronics, programming, Arduino, hardware experience?
Thanks.. Tom.. 