Hi, I have a 2000 Blazer 2WD and just need to know how to clean the connection plug for the crankshaft position sensor....If I unplug it to clean it when I plug it back in will I have to run the CKP Re-Learn Process or is this just if you are replacing it with a new one?.....My problem is not with the sensor it self I just need to clean the connection but don't want to mess any thing up....also even if I did replace this one is the CKP Re-Learn necessary or mandated to do?.....Thanks to all for the help....

 

Unplugging electrical connector from the sensor should not be a problem unless you do it visciously!

Disturbing the sensor by removing it and putting it back in - or by replacing it will require a Crankshaft Sensor Relearn.

If the inside of the electrical plug is so dirty that it needs cleaned - there may be a larger problem than just cleaning it. What's up with that?

 

What its doing is it won't get out of its own way it just chugs and it rev's itself up and down without touching the throttle, it will stall out when it feels like it......it does not do this right away from start up it may take a few minutes of driving after you start it up and if you shut it off for a few minutes when it starts to do this and then fire it back up it will be OK for a few more minutes and it does it again....I have a OBD Reader and it comes up "crankshaft position sensor intermittent" so I thought I would try cleaning the connection first before spending $70 on a new sensor......Thanks.

 

Does anybody know what would happen If I just replace this without doing a Re-Learn process?......Is it still drivable?....I was told that it will learn on its own and that this is not a mandatory thing......Thanks to any and all help.....

 

It will run and drive and not miss if all other things are working correctly, but SES may come on due to PCM not being able to correctly interpret crank sensor misfire information coming from the new sensor. Furthermore, SES light coming on may put PCM in a mode where other things are affected.

PCM will not learn the new Crank Sensor on its own - it absolutely requires a scanner to tell the PCM to begin the learn procedure. I am able to trip this relearn procedure and do other various tests with HPTuners Software and my laptop (wasn't cheap). Hand-held scanners that do the crank sensor relearn are not common becasue they require a license from GM for the GM-specific PIDs/controls (over and above generic OBD2 requirements) and are also typically quite expensive. Tech2 does it all and then some, but costs the most. Good luck!

I recommend going back to the basics. If you have steady spark from the coil to ground while cranking, it's simply not the crankshaft sensor. What code is it setting?

 

The engine will not be running at an optimum efficiency, but it will run.

It cannot learn this value by itself.

 

Thanks to everyone but it does not matter any more.....The truck Died today.....It stalled out and will not start anymore it will turn over but it just doesn't sound the same as it did so, its in the garage, will have to get it done next week when I get a Chance....I am not 100% sure but I think it may have jumped its timing......If anyone has any ideas they are much appreciated as I am on a hunt now....Thanks......I forgot to mention I did change the sensor and still won't fire up and run just turns over sounding very strange......

 

Remove the coil wire from the distributor, then try to start it. See if it cranks over and sounds normal with the coil wire removed.

 

OK changed the Crankshaft and camshaft sensor done the relearn had to replace the positive wire on the battery terminal....Truck ran great for maybe an hour to hour & a 1/2 then started right back doing the same thing again.....Now you can't drive longer than 5 minutes and it spits , sputters, Chugs and throttle some times does nothing and has no effect when it does this and if you put it in neutral you can't get the motor to rev past 2K, It also sounds like pop corn when it does this....I have tried putting it on a friends snap on diagnostics tablet and that shows everything is perfect...I am at a loss if any one knows what can cause this all help and advice is greatly appreciated Thanks......

 

If it's doing all this, you're not interpreting the scanner correctly There is obviously a problem


The "basics" must be correct. These are things that the OBDII system does not monitor directly, and they MUST be correct before attempting diagnosis.


Retrieve and post all DTC's.
AC Delco distributor cap, rotor, and plugs.
Plug wires.
Check & adjust camshaft retard, (mandatory after cam sensor replacement).
Check fuel pressure and leakdown, this thread explains, then post all 4 numbers: https://blazerforum.com/forum/2nd-ge...eakdown-88305/