Crank/Cam Sensor ... relearn? - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum



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Go Back   Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum > 2002 - 2009 TrailBlazer/Envoy Tech > 02-09 Vortec 4.2L I-6 Engine and Drivetrain > OEM Issues

OEM Issues Original Equipment Repairs and/or Problems

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  #1  
Old 02-05-2010, 07:58 PM
Chir Chir is offline
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2004 Chevy TrailBlazer LT
Tan 4.2L I6 4X4
Join Date: Nov 2006
Location: Grand Rapids, MI
Posts: 19
Crank/Cam Sensor ... relearn?

Greetings:

I am about to replace the crank and cam sensors. I'm reading about a relearn process that needs to be done, but I may be confusing it with something else?

After replacing these two sensors, do I have to have this relearn process done?

I am replacing the sensors becuase of a rough idle and a code that was thrown. I don't recall the exact code, but it said that the cam and crank sensors were not alighned. I also have lost a bit of power and cruise control no longer works.

Thanks.

UPDATE:
These are the parts that I have --
Crankshaft Position Sensor

Camshaft Position Sensor

After a little more digging - I think I'm confusing the Crankshaft Position Sensor actuator (what I actually have) with the Crankshaft Position Sensor. I believe you only have to do the relearn if you replace the sensor, not the actuator -- correct?

Thanks again!
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  #2  
Old 02-06-2010, 03:30 AM
WOOLUF1952 WOOLUF1952 is offline
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2003 GMC Envoy SLT
Magnetic Red Metallic 4.2L I6 4X4
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Location: Milwaukee, WI
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A Crankshaft Angle SEnsor (C.A.S.E.) relearn has to be done when the crank sensor is replaced.
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Old 02-06-2010, 03:13 PM
Chir Chir is offline
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2004 Chevy TrailBlazer LT
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Join Date: Nov 2006
Location: Grand Rapids, MI
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Is the Crank Sensor and the Crankshaft Position Sensor two different things or are they the same?

And the relearn isn't somethign I can do, correct? I need to take it to a dealer (or a mechanic with a special tool?) to do that?
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  #4  
Old 02-06-2010, 03:48 PM
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christo829 christo829 is offline
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2004 Chevy TrailBlazer LT
Silverstone Metallic 4.2L I6 4X4
Join Date: Mar 2009
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There's a way to run the relearn process without a TechII, but I'm having
trouble finding the one I saw for our vehicles. Here's one from the full
size chevy forums:

http://www.fullsizechevy.com/forums/...t-relearn.html

It's about a third of the way down the page.

Or just do a Google search for "CASE relearn without scan tool".

If I can find the other version I saw that was relevant to our models specifically,
I'll repost....unless someone else here finds it first.

Good Luck!

Chris
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  #5  
Old 02-06-2010, 07:13 PM
Chir Chir is offline
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2004 Chevy TrailBlazer LT
Tan 4.2L I6 4X4
Join Date: Nov 2006
Location: Grand Rapids, MI
Posts: 19
Awsome! Thanks for the link.

I believe this is the procedure, so I'll post it here in case someone else is looking for it:


NOTE: If the Crankshaft Variation Relearn is not accessible through your scan tool (some truck applications 1998 & later), perform the relearn in the following manner:

1. Turn off all of the accessories. With the Air temperature sensor and Coolant temperature within 5 degrees (Centigrade) of each other, start the engine and let it idle in Park or Neutral for two minutes.
2. Accelerate the vehicle to 55 mph at part throttle. Cruise at 55 mph for 8- 10 minutes until the engine reaches operating temperature.
3. Cruise at 55 mph for another 5-6 minutes.
4. Decelerate to 45 mph without using the brakes, and maintain 45 mph for 1 minute.
5. Perform 4 deceleration cycles, without using the brakes, of 25 seconds each where no specific speed is necessary. Returning to 45 mph for 15 seconds in between deceleration cycles.
6. Accelerate to 55 mph and cruise for 2 minutes.
7. Stop the vehicle and idle for 2 minutes with the brake applied and the transmission in Drive (automatic trans.) or Neutral (manual trans.) with the clutch depressed. Refer to diagram A on page 8.
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  #6  
Old 02-09-2010, 03:08 AM
toad43 toad43 is offline
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2004 Chevy TrailBlazer LT
Medium Sage Green Metallic 4.2L I6 4X4
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Location: Boulder Creek, CA
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Relearn

After replacing my motor, it seems like a relearn is necessary. But all of the relearn procedures I see are with the motor running. Can it be necessary for the relearn to take place to even get the motor to start? Would there be a relearn problem if I am getting fuel and spark?
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