Questionhello, i have volvo s70 glt 1999.My check engine ligth came on ,i think it is mass sensor,please if you know how to test mass sensor let me know,thanks.
AnswerFollow up on MAF signal specs:
Test the sensor by backprobing each terminal (push a sewing pin through the back til it makes contact with the terminal) and hooking the red lead of your voltmeter to it. Connect the black lead to a good ground. The most important wire to test is the signal wire though.
If you have a 5 wire sensor (Denso engine controller):
Wire1: (green / orange tracer) is 12 volt power. Will be that way when key is on.
Wire2: (brown / white) is signal ground. Should be low or 0 volts all the time.
Wire3: (green) is signal wire. .58 volts with key on, 1.33 volts with the engine idling (no load), and voltage should go up with airflow increase.
Wire4: (white) is combined intake temp sensor signal. not used for airflow calculation, not required to be tested.
Wire5: (brown / black) is component ground. Move black lead to battery + and you should see 12 volts. (only way to check for a ground).
If you have the 4 wire sensor (Motronic ME7 controller):
Wire1: Not used
Wire2: (green / orange) is 12 volt power. Will be that way with the key on.
Wire3: (brown / white) is signal ground. Should be low or 0 volts.
Wire4: (violet / white) is 5 volt power supply. 5 volts when key is on.
Wire5: (green) is signal wire. 1 volt key on, 1.7 volts engine idling (no load), and voltage will gp up with air flow.
So there you have it. That should be enough info to determine if the MAF is operating correctly. If it is operating correctly, be sure to double check that the signal is making it back to the controller. To figure that out check for resistance (ohmeter) of the signal wire from the MAF to the ECU. (ECU terminal 60 for 5 wire, terminal 22 for 4 wire). You may have to pull the computer to check that if it comes to that. Hope that helps.
James
