will 12 volts going to my sensors mess anything up?(rb25det)

[Sky240PWR]

well my mechanic said there was 12 volts going to my sensors, he said there should be only 5 volts going to my sensors and that would cause inaccurate readings, I guess my question is, is this normal or is my wiring screwed up?? I had Mckinney do my swap.

[Joe]

12 volts to all your sensors?

does your mechanic have any idea what he is doing?

the ECU sends 5 volts (usually) to sensors, if you are getting 12 to some, something is very wrong.

[cvc9216]

Some of the sensors do get 12 volts I think

[Sky240PWR]

maybe he said 12 volt wire, would that make sense?......and yes he knows what he's doing!!...I would trust this guy with my life!!

[JonPowell]

Which sensors? All of them or some of them? Be specific when asking a question like this because the engine has ALOT of sensors.

[Slo_240sx]

Your mechanic has no idea what he is doing. ALL automotive *engine* sensors receive 12v ignition on power. The 5v's is the reference wire sent back to the ECU depending on the engine conditions. A basic sensors will have mainly 2 or 3 wires but it needs these 3 items: 12v power in, Ground, and the varying 5v's back to the computer based on the conditions of what the sensor is reading. The only sensor that DOES NOT have 5v reference signal is the o2 sensor. An o2 sensor creates its own voltage signal of 0.0-1.0 volts and that also depends on engine condition and the amount of oxygen that is going through the exhaust.

1 - your mechanic doesn't know what hes doing2 - your mechanic is testing wrong leading back to number 1.

Ask him and be specific, which sensor, how many and which wires. Then we all can confirm.

-Alex

[cvc9216]

Your mechanic has no idea what he is doing. ALL automotive *engine* sensors receive 12v ignition on power. The 5v's is the reference wire sent back to the ECU depending on the engine conditions. A basic sensors will have mainly 2 or 3 wires but it needs these 3 items: 12v power in, Ground, and the varying 5v's back to the computer based on the conditions of what the sensor is reading. The only sensor that DOES NOT have 5v reference signal is the o2 sensor. An o2 sensor creates its own voltage signal of 0.0-1.0 volts and that also depends on engine condition and the amount of oxygen that is going through the exhaust.

1 - your mechanic doesn't know what hes doing2 - your mechanic is testing wrong leading back to number 1.

Ask him and be specific, which sensor, how many and which wires. Then we all can confirm.

-Alex

No, that's wrong. Most of the engine sensors receive 5V only. Except for the MAFS, which does work as you describe and a couple others, I think maybe the O2 sensor gets 12V and maybe the TPS...can't remember off the top of my head

[Wulfgang]

Get it right. As far as the ECU is concerned....

12 V------O2 sensor heaterMAFCASBoost sensor

Voltage producing sensors--------------------------------O2knock

Many of the sensors are resistive elements, which the ECU controls by sending a signal that is neither constant voltage or constant current. It is neither 12 V nor 5 V. These are:-----------------------------engine coolant tempair intake temp (if you have one)TPS

There are other things that are not sensors, such as the injectors, P/S switch, AAC, and air regulator. These all have 12 V supply.

In addition, there are sensors/switches that are only used for the gauges, such as the boost on RB20's, oil pressure, and engine temp. All of these have 12 V supply also.

So... no 5 V sensors anywhere.

[JonPowell]

maybe he said 12 volt wire, would that make sense?......and yes he knows what he's doing!!...I would trust this guy with my life!!

Your life is in jeopardy.

[Slo_240sx]

Get it right. As far as the ECU is concerned....

12 V------O2 sensor heaterMAFCASBoost sensor

Voltage producing sensors--------------------------------O2knock

Many of the sensors are resistive elements, which the ECU controls by sending a signal that is neither constant voltage or constant current. It is neither 12 V nor 5 V. These are:-----------------------------engine coolant tempair intake temp (if you have one)TPS

There are other things that are not sensors, such as the injectors, P/S switch, AAC, and air regulator. These all have 12 V supply.

In addition, there are sensors/switches that are only used for the gauges, such as the boost on RB20's, oil pressure, and engine temp. All of these have 12 V supply also.

So... no 5 V sensors anywhere.

Thank you Wulfgang. Almost all sensors are 12v power based. Injectors and such would be an output off the ecu instead of an input telling the ecu of engine conditions. Temp sensors are termistors and sensors such as the tps are variable resistors. ALL 12V. 5v reference back to ECM. Its not a 5V constant back its varies between 0-5 depending on engine conditions and 12volts back to the ecm will fry it. Nice write up wulfy.-Alex