MoTeC Global Forum

I would greatly appreciate advice on connecting a 5 wire MAF/IAT 2009 Subaru sensor. 2 of the outputs appear to be 0v but for the wires to be separate there must be a difference. I am guessing that one needs to be connected to battery ground to complete the hot wire heating circuit and the other to sensor ground for the IAT & MAF voltage signals.
Any ideas on how to work out which is which would be good.
Thanks in advance.

What does the factory wiring diagram shown in the workshop manual show? You can usually work out what the pins are for with the wire labels or ECU input description. I would expect that two wires with be the resistive temperature sensor and the other three the MAF sensor (power/ground/signal).

Thanks. That is more or less what I thought but I do not have the workshop manual and the engine is being used in a light aircraft so most of the inputs are non-OEM.
I have access to a stock 09 NA Forester and obtained the pin out values from the connector wires.
I was hoping that there might be some easy way to differentiate between the two 0v wires with a multi-meter or that someone might be familiar with the sensor. For the record, looking into the sensor and numbering from the left, 1 is the shielded MAF 0-5v signal, 2 = 0v, 3 = 12v, 4 = 0v and 5 is the other 0-5v signal.

How about measuring the resistance between 4 & 5, then add some heat (from a heat-gun?), and see if the resistance changes -- if so, that would be the temperature input, which would be my guess.

I look up Subuaru MAF and found it uses a Denso 197 6040 (also used on many Mazdas). I couldn't find a data sheet, but other pinouts showed pins "D" and "E" were the temperature pins.

Thanks again.
I managed to find a workshop manual with wiring diagrams and agree that the 0v pin adjacent to the IAT signal must be a sensor ground as it is connected to the ECU. The 0v pin next to the MAF signal does not go to the ECU so must be battery ground. Appreciate your help with this.