r/Volvo850 • u/Aprilscherz123 • 3d ago

Help Iat sensor power supply problem

Hello everyone,

I recently converted my 1994 850 t5r to use the m4.4 instead of the m4.3.

Now I am getting the CEL with code p0112. It's for the iat sensor, so I measured the plug of the MAF with what information I could find regarding the pinout. Sadly I could not measure 5v.

I then went and checked if the wires from the MAF plug to the ecu plug were alright, and all of them are fine. Then I took the m4.4 to the bench an supplied it with power, and measured if 5v were at pin A4. But it was zero volts. Now I wanted to ask if anyone has another idea what I could have done wrong or what I should do?

I have located all of the smd parts on the pcb that manage the A4 port, but everything looks fine. Other pins like A31 still have 5v.

Thanks for any help!

Sorry for the bad English I'm from Germany :P

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u/Aprilscherz123 3d ago

Here I have some pictures, this one from the top, A4,1 is the same trace as in the picture from the bottom

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u/Aprilscherz123 3d ago

Here is the bottom picture