Crank Position Sensor on CM871

[mxmom777]

What role does the crank position sensor play? Im having a debate and its being argued to me that all it does is read the tach.. what are common symptoms of one failing/failed?

Is there anyway one would get an engine light stating the DOC face is plugged, if this was failing?

[hhow55]

https://truckguider.com/cummins-isx-cran...-location/

[Rawze]

(08-07-2024 )mxmom777 Wrote:  What role does the crank position sensor play? Im having a debate and its being argued to me that all it does is read the tach.. what are common symptoms of one failing/failed?

That is a completely pointless argument. Sounds like some social medai crap to me.

The crank position sensor is one of the most important sensors on the engine.

It is used by the ecm to help determine proper injection timing, the position of the crank at any given moment, it is compared to the cam position sensor to ensure proper gear-train timing and a whole lot of other secondary things. things like cylinder mis-fire, too little or too much fuel in the cylinder detection, and a whole host of indirect systems rely on knowing exactly where the crank shaft is at any given moment.

When the sensor starts to fail or read incorrectly, the engine will resort to using the cam position sensor to 'Estimate' the approximate position of the crankshaft in attempts to keep the engine running so that it is not put you on the side of the road. In this condition however, the engine will be far less fuel efficient, it is harmful to the engine over time (bad injection timing, etc) and it will basically run crappy .. all while throwing a check engine light for the crank position sensor, or a crank-cam sensor mis-match error.

I.E.> IT DOES NOT MATTER WHAT COMPLETE MORONS WANT TO ARGUE ABOUT OVER ON THE SOCIAL MEDAI INTERWEBS GAGGLE OF DUMBARSSES ... OR SMARTARSSES ALIKE...

IT IS SIMPLE LOGIC.... THERE IS NO ARGUMENT.. THERE IS NO DEBATE ... ONLY AN UTTERLY COMPLETE MORON WOULD EVEN CONSIDER ABUSING THEIR ENGINE AGAINST FAILING SENSORS THAT ARE CRITICAL TO PROPER ENGINE OPERATIONS!!!!!!

IF THE SENSOR IS FAILING AND THROWING FAULTS, ACTING UP, ETC!. ... REPLACE IT AND FIX THE DAMN ENGINE PROPERLY!!!. OTHERWISE YOU CAN KISS IT GOODBYE WHEN IT BLOWS A HEAD GASKET OR PUTS A PISTON THRU THE BLOCK DUE TO ENGINE ABUSE FROM DRIVING IT AGAINST BAD SENSORS!!.


(The more people hang out on social medai and argue about nothing but stupidity.. exponentially.. the dumber they get) < Rawze

[mxmom777]

Is this plug play for this sensor and does the crank need to be pinned?

[Rawze]

(08-07-2024 )mxmom777 Wrote:  Is there anyway one would get an engine light stating the DOC face is plugged, if this was failing?

The crank (or cam) position sensor (unless its throwing faults and/or getting out of sync errors), will have nothing whatsoever do with any emissions system alarms.


A DOC faceplug alarms is just that.,. a clogged DOC element detection by the ecm.

REMOVE THE DOC ELEMENT AND TAKE PICTURES OF ITS FACE!!! .. Take it, and the DPF elements BOTH off and to the st#ealers$it and have them baked, de-ashed, and flow tested. perform a 'DPF replacement' procedure in insite when they are all clean and back onto the truck. Post pictures of their faces for opinions of what might have clogged them up as well. This can help identify why they clogged in the first place. Here is one example of this...
ref: https://rawze.com/forums/showthread.php?...7#pid10137


THEN follow it up by performing a full egr tune-up, and ensure the engine is running as healthy as possible so it does not clog it up again!!.

[Rawze]

(08-07-2024 )mxmom777 Wrote:  Is this plug play for this sensor and does the crank need to be pinned?

Its plug and play ... however if your getting crank position alarms, while the sensor is out, someone should also take the time to check that the tone wheel on the crankshaft itself is not getting loose. It is uncommon, but it does happen.

The tone wheel itself can be checked without removing the oil pan by using a long, fairly thin, flat-blade screwdriver and applying some pressure on the tone wheel thru the crank sensor hole, while looking down the hole (flashlight etc) for any tone-wheel movement.