What is reference voltage automotive?
A voltage reference is an electronic component or circuit that produces a constant DC (direct-current) output voltage regardless of variations in external conditions such as temperature, barometric pressure, humidity, current demand, or the passage of time.
How a bad circuit ground can affect a sensor reference voltage?
Poor computer and/or sensor grounds can cause higher-than-normal sensor voltages and false trouble codes. In many cases, the bad ground prevents the computer or sensor from pulling a voltage signal down to or near ground zero.
What is the purpose of a reference voltage?
A voltage reference is a precision device specifically designed to maintain a constant output voltage, even as parameters such as ambient temperature or supply voltage change. The precision of a voltage reference enables its use in several differ- ent types of applications beyond a data converter.
How does a pull down voltage sense circuit work?
A pull-down voltage sense circuit usually uses an internal voltage source within the processor card. It is also possible to use an external voltage source. The current limiting resistor is used to protect the processor card and the circuit.
What is the 5V reference circuit voltage drop?
If the 5V reference circuit (in-series) limiting resistor, for example, is 50 ohms and the sensor is 25,000 ohms, then the amperage would be .000199A, or 199µA. The clamp-on amp meter will not be able to measure amperage that low. Also, the voltage drop across the limiting resistor (50 ohms) is around .009V.
Can a voltage sense circuit read 0 volts?
With the switch in the open position the voltage sense circuit will read 0 volts. With the switch closed, the sense circuit should read close to reference voltage. Both of these circuits are limited concerning the ability to determine circuit faults.
Where does the pull up voltage come from?
The pull-up circuit will have a reference voltage through the switch. Usually the reference voltage will be provided directly from the battery or by the ignition switch. The current limiting resistor performs the same function in this circuit as it does in the pull-down circuit.
A pull-down voltage sense circuit usually uses an internal voltage source within the processor card. It is also possible to use an external voltage source. The current limiting resistor is used to protect the processor card and the circuit.
If the 5V reference circuit (in-series) limiting resistor, for example, is 50 ohms and the sensor is 25,000 ohms, then the amperage would be .000199A, or 199µA. The clamp-on amp meter will not be able to measure amperage that low. Also, the voltage drop across the limiting resistor (50 ohms) is around .009V.
With the switch in the open position the voltage sense circuit will read 0 volts. With the switch closed, the sense circuit should read close to reference voltage. Both of these circuits are limited concerning the ability to determine circuit faults.
The pull-up circuit will have a reference voltage through the switch. Usually the reference voltage will be provided directly from the battery or by the ignition switch. The current limiting resistor performs the same function in this circuit as it does in the pull-down circuit.