Testing Voltage on Sensors

[tiger]

I have searched the forum for information on this, but I can't find any so I hope that someone here could give me some directions on what to do. I want to test the voltage on my MAFs, but i'm not too sure how. I bought a voltage tester today. My ECU threw a code for the MAFs and I am pretty sure the sensor is shot, the car is running so horrible. I guess I need to know what the proper reading would be also. Thanks.

[benemorius]

Testing the MAF basically consists of putting the multimeter probes on the back of the connector while it's still plugged in. In order to look up exactly what the values should be, one would have to know what vehicle you have.

[tiger]

ok, I have a 93se with a 94 24de motor in it. does the car have to be running or the ignition turned on? Where could I look these values up?

[navysnail]

you can also use a pin, pierce the wire and use the multi-meter on the pin. just make sure to use a small pin and don't damage the wire

[Dano]

DONT PIERCE THE INSULATION FOR THE WIRE! unless thats absolutely necessary... but its not. You have to have the car running because the MAF works off of a signal voltage sent to the ECU, the air flow over the exposed wire changes the resistance, and the ECU reads the left over voltage and adjusts fuel maps/ timing curves/etc. accordingly.

For checking, make sure you voltmeter is a high impedence multimeter (most are these days, but some cheapos aren't) and use a small pin... back probe the connector NEXT to the wire until it bottoms out on the pin inside the connector (its probably a good idea to do this portion of the analysis with the key off)

As for the appropriate values, Scott's going to have to chime in.

-Dan

[NISTECH]

I agree with Dan. do not peirce the wire unless you have a roll of self adhearing electrical tape[$25 a roll] to properly reseal the insulation. Back probe it with a T pin. The idle value should be around 1.3 to 1.5 volts on the white wire. The B/W wire should be battery voltage and the B wire should be less then .2v. The black wire is your ground if its higher then .2v you need to run another ground wire.

[tiger]

im sorry but im so retarded about elec. stuff. Whitch one do you put on the harness, the red or black... when testing for ground, voltage, ect. Do you take the black one and stick it to a ground and touch the red one on the one you're trying to test?

[NISTECH]

yes put your volt meters black lead on the intake somewhere and put your red lead in one wire at a time . You will have your meter set on the 20v scale for the entire test. Write down the reading you get from each wire and post your results.