4loops

Hi All,

I am having trouble with a P1392 code "Camshaft Position Sensor, Open circuit or short to B+ (bank 2).

This is a 99 a4 quattro v6 30V DOHC 2.8L.
My camshaft position sensors only have 2 pins. I have seen forums about 3 pin CMPs, but that doesn't help me.

The obvious parts I know:There are several confusing factors:
*Unplugging bank 2's harness from the Cam Pos Sens yields no difference.
*Unplugging bank 1's harness (pass side) from its respective Cam Pos Sens does not make a difference either. Only the P1392 code shows, not the TDC indicating an error for Bank 1.

I have switched the Cam Pos Sensors, bank 1 to 2 and 2 to 1, to see if the code would follow the sensor. It did not make a difference. The DTC still says there is only a problem with Bank2.

I can hear the sensor actuating (metal rod rested on sensor to ear), but the computer still does not pick up a signal. -I am currently looking for an O-scope to verify actual waveform.

I have also taken some readings to try and help diagnose the situation:
*With the Engine off, I notice that Pin 1 of bank 1's harness and Pin 1 of Bank 2's harness are both tied to ground (continuity with battery ground and with each Pin1 of both harnesses)

*With the Engine on,I have tried every combination and troubleshooting technique I can imagine, and I can't get the p1392 code to go away. It keeps coming up in the pending for the first start after cleared codes, and then shows up active again.

Im not sure if this problem and the above measurements indicate a wiring fault, but that is the only thing I can think of, or maybe if an upstream harness came undone, something like that.

I appreciate the help,
-Isaac

Pete@ECSTuning

So if I understand this correctly, it doesn't throw a code if you unplug bank 1 but always throws a code for bank 2? I can't even fathom how that makes sense?!

This would make me think you are having a grounding issue with the whole system. It sounds odd, but try changing out the battery. Perhaps you have a faulty battery/ground/connection. It is a stretch but they are known to cause odd gremlins. I am inclined to think there is a bad short because it isn't triggering a code for bank 1.

4bagels

You might want to trace the signal all the way back to the ECU, and check for continuity between the corresponding ECU pin and the Cam Position Sensor. That will at least check the wiring between them.

4loops

Chris@ECStunning:4bagels:thanks for the replies,
-Isaac

4loops

Just yesterday, I got to thinking about how the cam sensor is actuated by a rod, which is actuated by the cam, might perform better if I make sure the oil is filled to full, for sure. Sure enough, I was low on oil. Filled it up hoping for a change, and that made no difference to the situation.
The only thing left I could think of at the time was timing. I know that if the timing was off, it should throw the respective code, but you never know, It might be off enough to make one code go and not the other. Disassembled the front end, and found the timing to be off by only a scoche. I have the correct tools to adjust the timing (the crankshaft lock pin and the cam alignment tool), and the alignment tool would have fit in very snugly. (I would have had to pry a little, but a no-no for such a tool). Appropriately, I realigned the timing. Rotated the engine a few times, checked again, still dead on timing. I turned on the engine and reved a few times. Checked again, still dead on. Still, the P1932 code is being thrown.

This is quite a perplexing problem. The good news is is that I know I can disassemble the front end of the car, do the timing, and put it all back in under 2 hours, but thats cancelled out by the silly code thing still haunting me...

I guess I can still google around and waste about 5 hours finding a wiring diagram, but it doesn't hurt to ask.. Anyone know the pinouts to the ECM for this model?

Thanks again,
-Isaac

4Driver4

I'd buy a new CPS, or use a known good from another engine. I don't like the idea of switching them back and forth.

4loops

4driver4:
That might do the trick.. Im hoping to get ahold of an oscope here within the week and test the waveform of the CMP, well, both banks' CMPs. and see if theyre outputting a correct voltage. Switching them should've made the code folllow the sensor though, at least I should think. I wouldn't think they were both bad, or I would think I'd see a code thrown indicating the problem for both Cam Pos Sensors. That is, unless, if bank 2 is bad, the ECM doesn't even worry about sending the code for Bank 1. Which might explain why (whether the Bank1 harness is plugged in or not) the ECM does not throw a code for Bank1. But this would really counteract the effectiveness of OBD2, then, wouldn't it? Another reasoning.. you wouldn't think that these harnesses are actually connected together in parallel with eachother to the ECM, and utilize multiplexing you think? I'm really gonna have to get that scope to find out though for sure, I really don't want to spend 50 to 80 to even 100 bucks on another CMP if it "might" do the trick.

If things come to worse, after I check some wiring and signals, I might give that a shot though.. you never know with the misterious electrical poltergeists though.. lol.

Thanks for the insight once more,

-Isaac

4Driver4

My thought is that it's a cheap part. I've always just tossed the old one out and installed another. I don't know if they are the same side to side.

4loops

Everyone,
My issue is solved. I have been away from AudiWorld for some time.
My issues explained in my previous posts were valid, but not all of my information was correct. I was looking at the wrong component on the heads. I switched out the camshaft position sensor and the code cleared.
A simple solution for such complication I guess.
Thanks.

4loops

...and for the V6 2.8, camshaft position sensors are the same right to left bank.

Again, thanks for your help on this issue.