PSM & ABS lights, code P0102 - help?

Hi all, I've now been chasing down a PSM + ABS lights issue for way too long. Originally started about a month ago after the car sat for winter and I replaced the water pump & spark plugs. I've cleaned my MAF in the past due to PSM+ABS lights, so I figured the quick fix was to order a new MAF. Put the new MAF in the car and the PSM+ABS lights did not go away. Ugh. I connected durametric to the car, my MAF reading looks ok, ~25 kg/h @ idle; ~70 kg/h @ 2500 rpm. I looked at the 'Hot film MAF' voltage reading via Durametric and I get 0.03V, where I think the spec calls for 1.2V to 1.4V. To double check this bad voltage reading I pulled out the power probe and connected to pin 5 (from this thread) , put the key in - read 0.0V, start the car - read 0.0V. It sure looks like I have a voltage problem. I see a procedure to check the wiring harness, but it requires 'Special Tool 9616' - which I don't have, nor do I know what it does. Can anybody help me diagnosis this further? I've already thrown a new MAF sensor at the problem, I'd like to understand it better before throwing the next part at it. Thanks!

stock air filter/intake? or aftermarket? check out this link: http://www.6speedonline.com/forums/9...2-problem.html

krom, Stock air filter (replaced about a year ago). I did read that link before - another special tool I'll try disconnecting the battery. I also saw the 'bad throttle body' comment, but no data to backup why. Not interested in buying a new throttlebody if I can get away from it. Anyway to test them?

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Everything you tested indicate you have a MAF problem. MAF reading should be between 15 to 20kg/hr @idle, warmed engine, not ~25kg/hr Hot film MAF should be close to 1.3V @idle. Please remove the MAF and check the following pins on the MAF connector carefully, with key in the last position before cranking: Pin 2 : ~12v Pin 4 : ~5v You have a wiring problem if those don't check out. Pin 5 is the signal GENERATED by the MAF so with it removed, you would get 0v.

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Hi Ahsai, thanks for the help - this is exactly what I was looking for. I put the key in and got these readings: Pin 2: 12.3V Pin 4: infinite The power probe didn't recognize any connection at all to pin 4 (it reads 0 on pin 5). Think I have a broken wire somewhere? Thanks

What year and model is your car? Need to check the correct wiring diagram. Sounds like you have an open wire from the DME to the MAF. The DME supplies the 5v (reference voltage) to pin 4. You're supposed to get 0 from pin 5 as it's connected as an INPUT to the DME. BTW, those measurements were done with the MAF removed and not back probed with it connected, right?

Actually, which version of power probe you're using? Does it display the actual voltage measured? If not, you need to use a regular multimeter. A regular power probe may be confused by 5v since it's not close to 12v or ground.

Correct, MAF removed - not backside probing. Understand the pin 5 = input, I poorly said that the Power probe is showing pin 4 as a complete 'no connect'. I have a 2002 C2 Cab.

Please check post #7. Pin 4 (Violet/Red) connects to plug B pin 22 on the DME. If you still can't get 5v on pin 4 using a multimeter, you need to check continuity between pin 4 and B22.

Ah - I missed post 7. It's a Power probe 3 - shows real voltage I took out a regular multimeter and it showed identical results (12V on pin 2, 0V on pin 4). I'll have to pull out the WSM to figure out where plug B is on the DME, I've never mucked with it.

I'll use this procedure to find the ECU. Still not sure how to get the correct bundle after I get that far.

Our 7.8 DME has 5 plugs (A to E, or sometimes labelled as I, II, to V) so B is the second one. The way the cables bend, usually it's easiest to disconnect them one by one in order (plug A first). And no you don't need that special Porsche tool. Just make sure you disconnect the battery first before unplugging the DME connectors. Are you a tech? PP3 is pretty advanced

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You can see the plugs labelled #1 to #5 in the photos. B is #2.

And use this DME pinout diagram http://www.6speedonline.com/forums/9...ml#post3152221

Hmm, can you double check that B is correctly labeled '2' in the sharkwerks page? That connector is a 40 pole bundle. The 6speedonline pin out you linked has bundle '2' (aka 'B') as a 24 pole group. I'm a tech enemy - an engineer . Plenty of theoretical knowledge, minimal hands on experience. Very dangerous

Ok, I've based this experiment solely off the wiring diagram which shows pin 22 of connector II as the 5V supply for the MAF. I did a continuity check between the MAF connector and the DME connector and get nothing. [deleted section] Edit: My procedure is solid - I double checked. I was also able to verify other wires have continuity (MAF sensor wire to pin 5 of MAF connector). I have a broken wire for sure. Any recommendations on how to proceed? Splice in a new wire into the connector?

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Lol. Ok, I hope I'm less dangerous then Yes B=2=24 pins I would suggest disassemble plug B and extract the pin 22 male pin/cable. Then buy the same male pin and crimp it on a new wire and run that wire to the MAF directly. Do the same on the MAF plug and extract the female pin. That way everything can be reversed and no splicing needed.

See post #11 here https://rennlist.com/forums/996-foru...l#post11556498 I have not tried the MAF connector side but you can try to apply the same principle.

Interesting - I guess I'll give it a try. I was more worried about the DME connector, but your picture shows it's possible. The MAF connector looks much easier to screw around with. I guess I'm off to Fry's later.

The DME female pins are not easy to find. I have the part numbers if you can wait till tomorrow.

This is the female pin for the DME connector http://www.newark.com/te-connectivit...awg/dp/35M2557

Alright, here's my near-final summary. Ahsai - thank you very much for all of your help. The car is running better than it's run in years! Read the full thing and you'll see why. Starting off, I didn't fully take your advice. I got the DME side connector taken apart with no problem, but the MAF side connector (the one I wasn't worried about) was near impossible to disassemble. I quickly decided that it was not something I would easily find and instead of ruining it, I just left it alone. I decided to use butt-end connectors and a new wire. This morning I put a new wire on the DME side, reassembled that whole bit and connected the battery. I found an unused grommet into the engine bay on the passenger side of the car and fished the cable through there. butt-end connector on DME side Grommet to engine bay So now I had the wire in the engine bay. I reattached the battery and tested it out - getting the expected 5V. At this point I was starting to think - how unlucky am I to have a single broken wire in the wiring loom? Seems like I should have more problems. I then ran across this mess - on the MAF wiring bundle from the DPO (dumb previous owner). Electrical tape over the factory wiring loom Hmm.... I took it apart and found this: Broken wire.... Ugh. That broken wire is the 5V supply wire. Well that explains it all! I am ashamed to say, I noticed this electrical tape mess a few years ago when I did my clutch + IMSB and thought nothing of it. I cleaned up the mess, spliced in my new wire and put everything back together. I'm not super proud of the cleanliness in the engine bay, but I was limited because of this broken wire. Tested it all out and the car runs great! I think I'm going to return the new MAF I got (if they'll let me) and save the money there. Now here's where it gets even more exciting. For years now I have been chasing down a very intermittent stumbling issue. Ahsai, you even helped me out with that. The issue originally started out after my clutch job. I suspect it has been this broken wire all along. It just so happens that when I replaced my water pump last month (removing the MAF & airbox), I completely broke the wire and made the problem that much worse. Now it's all fixed and I hope to have solved a bunch of my issues!

Wow, very nicely done! I like the fix. Looks like the broken wire was gnawed by some rodent and you were lucky to jolt it and break it completely - then it became a lot easier to diagnose. Looking back at your previous thread, the MAF signal drop out to 0 was present albeit intermittent. I wonder what would have happened if we had continued with that diagnostic path. If you had replaced the MAF and still saw the same drop out, then we would have also suspect the 12v and 5v supplies to the MAF. To diagnose further, you'll have to back probe and use a voltage data logger (not durametric) to log both the 12v and 5v wires. then you should see the 5v wire voltage drop out. Then you would have gone to check the 5v wire. But still it was intermittent at the time so it was difficult to catch it in action. Anyway, I love happy ending!

Alright, I see a "MAF Guardian" patent coming up...

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hi everyone im tim from philippines! I would like to ask what should i do if Pin 4 is only throwing .04v and not 5v l ? What should i do to fix the problem because i already changed my maf sensor for a new one but still the computer is throwing P0102 Hot Film MAF Sensor fault. thank you admins and everyone!