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Replaced Crank Position Sensor: Need to know "learning procedure"

Had to replace the Crank Position Sensor in my 97 Dually 7.4L.

The haynes manual says it needs to be taken to the dealer for a learning procedure to accept the new sensor.

Has anyone done this or am I stuck having to take this thing in?

Your help will be appreciated.

Rob
 

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Re: Replaced Crank Position Sensor: Need to know "learning procedure"

Depends on if you have access to a scan tool.
If you;
A.) Do, follow this procedure *
B.) If NOT, follow this procedure **
* With a scan tool:

Set the parking brake.
Block the drive wheels.
Ensure the hood is closed.
With the scan tool, monitor for DTCs. If a DTC is set, refer to Diagnostic Trouble Code (DTC) List/Type before proceeding.
Start the engine and allow engine coolant temperature to reach at least 70°C (158°F).
Turn OFF the ignition.
Select and enable the crankshaft position variation learn procedure with the scan tool.
Start the vehicle.
Apply and hold the service brake pedal firmly.
Ensure the transaxle is in park.
Increase accelerator pedal position until the fuel cutoff is reached at 5150 RPM. Immediately release the accelerator pedal after fuel cutoff is reached.
The crankshaft position system variation compensating values are learned when the RPM decreases back to idle. If the procedure terminates.

Recheck the ECM with a fresh 'scan' and see if the code "P1336" dispalys "Pass" or "Fail".
If it says "Fail" then preform the procedure again.

** 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.


Lots of good info on here also - http://www.fullsizechevy.com

Same info is in this reply - http://www.fullsizechevy.com/forums/general-discussion/performance/port-injection-96-obd-ii/164702-gm-computer-relearn-procedure-including-crankshaft-relearn.html
 

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Re: Replaced Crank Position Sensor: Need to know "learning procedure"

Thanks John,
No scan tool, may have to try to pick one up.

Problem for no scan tool procedure is getting it started: apparently this sensor has something to do with advancing the timing 50 degrees only while cranking to get it started. Have already cracked a starter housing due to too much compression during cranking. And then snapped off a starter bolt cranking with a new starter.

I'll check the links you provided for more info when I get home from work.
 

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Re: Replaced Crank Position Sensor: Need to know "learning procedure"

Is it a single sensor or a dual sensor set-up :confused:
The dual sensors are usually not a problem to restart. Just need to 'relearn' where stuff is ...
I have seen a single sensor system cause the engine to idle very rough and be slugish until the dealer did a relearn - cost under $100 for them to do it and reflash the unit with a code upgrade available for the car anyway.

You can always drive to a local chain auto parts store and have them pull the codes for you if it starts.
 

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Re: Replaced Crank Position Sensor: Need to know "learning procedure"

It's a single sensor.

Has been running great after it starts, initially thought I just needed a battery because it was cranking slow.
 

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Re: Replaced Crank Position Sensor: Need to know "learning procedure"

Wow. I never thought that it was a single sensor on the Crank Position Sensor. Sometimes, it would really act up not that good in order for us to really have it going. Replacing it with a good part will really give us something out of the bargain. Hope you got what you are looking for a part that will fit your car and your expenses.
 
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