Has anyone heard of setting the gap on a crankshaft sensor?

Question

hi,
the reason i'm asking this is I'm having some trouble with a crankshaft position sensor on my 05 GMC Duramax LLY, I've replaced it and so far it didn't fix the code, which reads that the crankshaft position sensor is not reading "P0374" and I've heard that when installing the sensor, it's necessary to set the proper gap between the sensor and the wheel or else the sensor will not read. Is this true? And if so, does anyone know the proper gap to set a crankshaft sensor on my Duramax?
Please only honest and to the point answers, none of the *insert brand name here* rule! GMC's are junk answers, I happen to really like my Duramax GMC, I'm sorry if anyone else does not, that's why you like what you like.

Answer 1

yes.you need a special tool..heres a pic of it



http://www.etoolcart.com/ProductImages/pictures/J-37089-B-L.jpg

Answer 2

first let me start by saying I don't have much experience with the duramax engines, but I am an accomplished engine management systems technician, and a former ase master certified gm dealer service/diagnostics technician. And secondly, the special tool referenced in one of the other answers is not applicable to the duramax engines. It was used on the 3800 V6 engines with dual relector rings on the back of the crank pulley.



There is a bulletin referring to shimming the crank sensor but that in not applicable to this engine, only the 4.3V6 gas engine. The service manual makes no references to shimming the crank sensor on the duramax engine. I did not find any applicable service bulletins referring to the crank sensor on the duramax engine. The service manual does make a reference to the crank sensor spacer and that if it needs to be replaced, use the spacer with a "C" marking on it. the original with have an "A" marking on it. There is one bulletin that may lead to discovering the source of the problem. There is a harness connector in the engine compartment, C107 in particular (the other are C108, C118, and C119) where the termimals may not seat properly due to damaged terminal locking tabs. this may allow the terminals to partially back out of the connector causing misc concerns. The other thing I wanted to mention is the possibility of having to do a crankshaft variation learn after replacing the crank sensor. I don't know if it is necessary on the duramax but it is required on the gas engines. Sometimes the gas engines will set false misfire codes, and performing a crank variation relearn with eliminate the codes. There service manual does not indicate that the relearn procedure needs to be done. The first thing I would do is use a lab scope to check the wave form of the crank sensor and compare it to a known good wave form. Of course, this would be after checking for 12v+ reference signal to the sensor and checking wire continuity from the sensor to the ecm. This may lead you to the C107 connector having a terminal partially backed out making either poor or no connection at all.

Answer 3

I don't have the service manual in front of me and I am not a certified tech. I have been working on anything that runs for 40 years. I don't want to waste your time; I would say set it around .040, clear the code and try to crank the motor. if that resets the code, set it at .35, and move it in no more than .005 each time. -hope this helps.

(addendum) -sounds like bbking48 has all his ducks in a row. this guy has his sh*t together and the info he laid out will get your truck back where it needs to be... I am clearly in the old school. -way to go man.

Answer 4

sounds right. I imagine it isn't too much different than points on a distributor. have you tried asking the guys at the parts store yet because alot of information like that is usually on their computers. otherwise I subscribe to the "get a manual" rule of thumb.