Crank position sensor location???

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Greetings and salutations to all Bitogers everywhere - All hail! So, with my new nifty OBD II code reader, I read the codes on my son-in-law's '96 Buick Century station wagon with the 3.1 V-6 One of the codes that it reported was PO336, Crankshaft position sensor A Circuit. After a great deal of internet surfing, I've discovered there are no less than two sensors on this car. One lives under the harmonic balancer which must be removed to replace the sensor, (Yikes!). The second sensor however, escapes me. Auto Zone lists it as do other parts web sites. I think I found where it lives but am not entirely sure. I found a sensor in the bell housing of the transmission on the drivers side of the vehicle, almost directly below the throttle body housing. Is this the other crank position sensor? Before I go wrenching and yanking, I want to make sure I'm wrenching and yanking the proper parts. If it so happens someone knows that this is in fact the crank position sensor AND an easy, nifty way to get it out without cursing the automotive gods, please share. Just as a refresher, this is a 1996 Buick Century Wagon with the 3.1 V-6. As Doctor Klahn would say: "You have my gratitude."
 

dishdude

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You have a crank and cam sensor circuit code...a little odd to have both IMO. I'm not sure I would go and just replace both sensors without some additional diagnostic work.
 
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Originally Posted By: GreeCguy
PO336, Crankshaft position sensor A Circuit.
That's actually a ZERO, not the letter O. The code is P0336. Forget any other sensors. If you have a P0336, that's the crank sensor at the nose of the crankshaft. The problem with OBD-II is that all it does is report detected problems with a particular system. It does NOT tell you WHY there is a problem, or WHAT part is actually causing that problem. My feeling is that OBD-II is responsible for more unnecessary parts-replacement than anything ever has, in the history of auto repair. Your problem could be a bad sensor, or it could be a wiring issue. Or it could be something else sort-of related to the physical environment surrounding the sensor. http://www.obd-codes.com/p0336
 
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if it runs it is probably not the sensor but note: The engine must be cold when replacing that sensor otherwise it will stick and not come out.
 

GreeCguy

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Okay, so I've been surfing the net, reading all about crank position sensors, cam position sensors and ICM's all evening, (and my eyes are about to pop out of my head - uggh!). From what I can gather, if the crank position sensor is bad, the vehicle will not crank. It's either a go or no go situation. Is this correct? If so, I'm thinking, (from what I have read this evening) that if the ICM has gone bad it might be sending bad signals to the crank position sensor which would then show up on my OBD II reader as a faulty crank position sensor. Is this correct? If so, I should be strongly leaning toward the ignition control module for the cause of my problem, (running rough and poorly and stalling out at times)and not the crank position sensor. Is this correct?
 
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Originally Posted By: GreeCguy
if the crank position sensor is bad, the vehicle will not crank
No. The engine may crank just fine, but not start. Or there may be NO SYMPTOMS AT ALL. Go read that link I gave in my original reply. It's written in an easy-to-read manner. Here it is again: http://www.obd-codes.com/p0336
 
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There are 2 crank sensors, one on the timing cover (24x pulses) and the other screwed into the backside of the block called the 7x crank sensor. I've never been able to see the one on the back side, and I've owned a '96 Century (3.1L) since it was new. I've seen the front one cause drive ability problems, I believe when the back one quits (7x) the engine will not start (crank but no spark). One controls spark (7x) below a very low RPM (appx 1200rpm) and the other (24x) above the threshold. You may try even unplugging the front one to see what it does. The connector is away from the sensor, but you can follow the wiring. You have to remove the harmonic balancer to replace the sensor. Also, the 7x wires directly to the ignition control module (underneath the coil packs) the ECU monitors it off a different lead from the ICM, while the 24x goes directly and only to the ECU. There is also a camshaft position sensor (behind the PS pump, straight down into the block), but it is unrelated. It is only used to fire which bank for the SFI. At worst, it fires the injector in banks 180 degrees out, but runs fine. My first,second and third guesses are a bad 24x on the timing cover, not really too bad pulling the HB through the wheel well and the ignition control module a distant fourth (and the most expensive).
 
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Code 0336 does reference the 24x sensor and 0341 references the 7x Forgive my above explanation if it is confusing as well, I'm pulling it from the FSM and it is not written as well as GM manuals were 30+ years ago. I had the 24x cause problems like yours, but only after a hot restart. Would hardly stay running, but still fine above an idle. It wouldn't even set a code!
 
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After reviewing your other post with the other codes listed, I do wonder if you may have a bad ICM. However, the procedure suggests which codes to start with, which is usually the first code. This has been my personal experience as well. Some of the sensors share wiring, i.e. the cam position sensor and the 24x on the crank, so multiple codes can frequently go together with wiring issues as well.
 

GreeCguy

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I finally found that bad boy. It lives way on the back side of the motor right above the oil pan beneath the alternator. I know there are two, (one behind the harmonic balancer, but for the life of me, I couldn't find the other one until about an hour ago). I had to lay on top of the motor with a flashlight and do some contortions, but there it is. If I must remove that one, I think I'll pop out the alternator and have a go at it as I can barely put my arm down there, let alone move a tool around. Right now, the car is running well after replacing the cam position sensor, fuel filter and cleaning the coil pack terminals. Hopefully, (prayerfully) this will solve the problem and the crank position sensor and stay where it's at. Thank you all very much for the wisdom and guidance - it's been a good day smile
 
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