Help translating test instructions from service manual
Hi. I'm getting ready to test my MAF circuit as I'm getting a P0100 with a new MAF sensor. I also received these codes with an different working MAF sensor.
p0100 [Pending] Mass or Volume Air Flow Circuit
P0173 [Pending] Fuel Trim
So, I go to my handy Star manual and under "Hot-film mass airflow sensor - ME - SFI gasoline injection system - Testing electrical system" I see the following (in addition to further testing info):
Under 1.1 it shows "N3/10 104", "- +", and "B2/5 4".
As far as I can tell, "B2/5" corresponds to the MAF sensor, though I can't do a part lookup by that code. So does "B2/5 4" mean pin 4 on the MAF sensor? I have also done some googling (because searching for n3/10 in the star manual does no good) and found that it was the "ME-SFI control module". Does this module have a pin 104? I couldn't find one in the electrical diagrams. Is there a different way to read this?
They are telling you that socket #4 is the brown/yellow wire. Stop trying to guess where the brn/yellow wire is and strip away the covering on the MAF wire harness and look to what prong the wire leads to.
You also have to remember that all of these symbols and nomenclature are for use with a Star Dianostic scanner, which you don't have.
Could you also Edit your Profile under User CP to include what year and model truck you have.
They are telling you that socket #4 is the brown/yellow wire. Stop trying to guess where the brn/yellow wire is and strip away the covering on the MAF wire harness and look to what prong the wire leads to.
Oh, so "socket" refers to what I would call the "pin" or "prong". That clears that up.
Quote:
Originally Posted by 43sqd
You also have to remember that all of these symbols and nomenclature are for use with a Star Dianostic scanner, which you don't have.
Ok, that makes more sense.
I have since figured out that that symbol that looks like a plug with 32 pins is actually representing a 126 pin breakout box. Anyone know a place to pick one up cheap? Also, can this socket box work independent of the Star Diagnostic scanner (that I don't have and Mercedes probably wouldn't sell to me)?
Forget the breakout box, you do not need it. Here is what I suggest you do. There are five wires that operate the MAF. One is a 12v power supply and the other four go directly to the Eng. Computer without any splices or connector. So the simplest method is to check for continuity on those four wires, from the MAF sensor to the computer.
First disconnect the plug from the MAF and then turn the key to the on position. Using a test light see that you have batt. voltage at the Red/Blue wire.
If you have voltage, turn the key off and disconnect the neg. battery cable. Go to the computer and it should have five connectors plugged into it. According to my diagram, look for the plug which has the most wires running in it, C3 on my diagram. In that plug you should find all the remaining wires from the MAF; Yellow/Green...Brown...Brown/Yellow...Yellow/White
Then wire by wire, do a continuity check between the MAF and computer. Make sure you get a good contact on both ends.
I got lucky on this one. I traced out the harness and didn't see any damage or other indication of a problem. Also, choosing the lazy route first, I swapped my "new" MB dealer installed MAF with a new MAF from germanstar that I just put in the other ML, and the codes went away. My ML has now been driving like a dream.
Next up is reinstalling the MB dealer MAF, waiting for the codes to come up again and getting it replaced under warranty.
BTW, is the dealership warranty on parts 6 months or 1 year?
I got lucky on this one. I traced out the harness and didn't see any damage or other indication of a problem. Also, choosing the lazy route first, I swapped my "new" MB dealer installed MAF with a new MAF from germanstar that I just put in the other ML, and the codes went away. My ML has now been driving like a dream.
Next up is reinstalling the MB dealer MAF, waiting for the codes to come up again and getting it replaced under warranty.
BTW, is the dealership warranty on parts 6 months or 1 year?
Not sure. It goes dealer to dealer. But they aren't going to warranty anything if you tell them you installed it yourself. You might have to show them a bill from a repair shop.
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