Anyone,

1999 Chevy K2500, 5.7L, 4 spd Auto, with A/C, with cruise, anything else
needed?

What does it mean? How do I fix it?

Thanks.

ed
here's what i found:

good luck

paul





The crankshaft position (CKP) sensor is mounted in the front of the engine
behind the harmonic balancer. The CKP sensor works in conjunction with a 3X
(4X on V8 applications) reluctor wheel mounted on the front of the
crankshaft. The CKP sensor has a B+ power supply, a ground, and a signal
circuit.

As the crankshaft rotates, the reluctor wheel teeth interrupt a magnetic
field produced by a magnet located in the sensor. The sensors internal
circuitry detects this field and produces a frequency which the control
module monitors on the signal circuit. The control module uses this signal
in order to accurately measure crankshaft velocity, which is important to
ignition control spark timing, fuel injector timing, and for misfire
detection.

The control module can detect small variations in the CKP sensor and
reluctor wheel. These part tolerances must be learned by the control module
before an accurate CKP signal can be determined. At high engine speeds,
slight variations in the following components make misfire detection
difficult:

Crankshaft
Reluctor wheel
CKP sensor
The control module learns variations during the Crankshaft Position System
Variation Learning Procedure, and compensates for these variations when
performing misfire calculations. Only a scan tool can command the control
module to perform the Crankshaft Position System Variation Learning
Procedure.

Perform the learning procedure after the following actions:

A control module replacement
Any operation or repair involving the crankshaft, the CKP sensor, or the CKP
sensor to reluctor wheel gap relationship
An engine replacement

Important
A control module power disconnect with the ignition ON may erase the stored
pulse value and set the DTC P1336.


Disconnecting the control module will not erase the learned crankshaft
position system variation as long as the ignition switch is in the OFF
position.


Important
Reprogramming the control module does not require running the Crankshaft
Position System Variation Learn Procedure unless the module is new or from
another vehicle.


If the crankshaft position system variation is not within an acceptable
range, or can not be learned, DTC P1336 sets.

Conditions for Running the DTC
The engine is running.

Conditions for Setting the DTC
The VCM has not learned the crankshaft position system variation

Action Taken When the DTC Sets
The control module illuminates the malfunction indicator lamp (MIL) the
first time the diagnostic runs and fails.
The control module will set the DTC and records the operating conditions at
the time the diagnostic fails. The control module stores the failure
information in the scan tools Freeze Frame/Failure Records.
Conditions for Clearing the MIL or DTC
The control module turns OFF the MIL after 3 consecutive drive trips when
the test has run and passed.
A history DTC will clear if no fault conditions have been detected for 40
warm-up cycles. A warm-up cycle occurs when the coolant temperature has
risen 22°C (40°F) from the startup coolant temperature and the engine
coolant reaches a temperature that is more than 70°C (158°F) during the same
ignition cycle.
Use a scan tool in order to clear the DTCs.
Diagnostic Aids
Check for the following conditions if the Crankshaft Position System
Variation Learn Procedure cannot be learned:

A chipped or damaged reluctor wheel
Incorrect alignment of the CKP sensor to the reluctor wheel
Excessive crankshaft run-out
Interference in the signal circuit to the CKP sensor
Incorrect ratio of crankshaft to camshaft pulses

Important
The VCM will not allow the scan tool to enable the learn procedure when an
incorrect crankshaft to camshaft ratio is received.


The engine misfire diagnostic is disabled when the engine speed is more than
1000 RPM and this DTC is active.

When the learn procedure is in progress and the engine speed is at 4000 RPM,
a decrease in engine speed will occur. During the engine coastdown, the VCM
monitors the CKP sensor signal and stores the pattern. This pattern is used
to determine if the crankshaft speed variations are due to an engine
misfire.

An intermittent may be caused by any of the following conditions:

A poor connection
Rubbed through wire insulation
A broken wire inside the insulation
Thoroughly check any circuitry that is suspected of causing the intermittent
complaint. Refer to Intermittents and Poor Connections Diagnosis in Wiring
Systems.

If a repair is necessary, refer to Wiring Repairs or Connector Repairs in
Wiring Systems.

Test Description
The number(s) below refer to the step number(s) on the diagnostic table.

The VCM enables the learn process after 65°C (150°F) is reached. Engine
deceleration occurs when the learn procedure is in progress. The VCM
monitors and records the CKP sensor signal during engine coast down
conditions.

TEST IN PROGRESS on the scan tool indicates the VCM is performing the learn
procedure. If the VCM receives an incorrect crankshaft to camshaft pulse
ratio, an incorrect transmission range signal input, corrupted
communication, or no change in the brake switch input, the learn procedure
will not be allowed.

If a repair is necessary due to a condition which prevented the learn
procedure from enabling, the Crankshaft Position System Variation Learning
Procedure must be performed.

The ignition must be in the OFF position for at least 10 seconds after the
learn procedure is complete and the engine RPM has returned to idle. The VCM
saves the signal data after these conditions are met.

Step
Action
Value(s)
Yes
No

1

Important
Before clearing the DTCs, use the scan tool Capture Info to save the Freeze
Frame and Failure Records for reference. The control module's data is
deleted once the Clear Info function is used.


Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?
--
Go to Step 2
Go to Powertrain On Board Diagnostic (OBD) System Check

2
Perform the CKP System Variation Learn Procedure. Refer to CKP System
Variation Learn Procedure .

Does the scan tool indicate that CKP System Variation Learn Procedure is
completed?
--
Go to Step 5
Go to Step 3

3
Attempt the CKP System Variation Learn Procedure as many times as the
specified value.

Does the scan tool indicate that CKP System Variation Learn Procedure is
completed?
3
Go to Step 5
Go to Step 4

4
Check the Crankshaft Position (CKP) sensor and the Crankshaft Reluctor
Wheel for damage. Refer to Diagnostic Aids.

Did you find a problem?
--
Go to Step 6
Go to Diagnostic Aids

5
Turn OFF the ignition for 15 seconds.

Is the action complete?
--
Go to Step 8
--

6
Replace the Crankshaft Position (CKP) sensor and/or the Crankshaft Reluctor
Wheel. Refer to Crankshaft Position (CKP) Sensor Replacement or Crankshaft
Position (CKP) Reluctor Ring Replacement in Engine Mechanical.

Is the action complete?
--
Go to Step 7
--

7
Perform the CKP System Variation Learn Procedure. Refer to CKP System
Variation Learn Procedure .

Is the action complete?
--
Go to Step 8
--

8
Using the scan tool, clear the DTCs.
Start the Engine.
Allow the engine to idle until the engine reaches normal operating
temperature.
Select DTC and the Specific DTC function.
Enter the DTC number which was set.
Operate the vehicle, with the Conditions for Setting this DTC, until the
scan tool indicates the diagnostic Ran.
Does the scan tool indicate the diagnostic Passed?
--
Go to Step 9
Go to Step 2

9
Does the scan tool display any additional undiagnosed DTCs?
--
Go to the applicable DTC table
System OK

Thanks Paul,

Yours is by far the most info I've received. Out of the service manual?

In the last week I have found out basically what it meant, not necessarily how
to "really" fix the problem though. I talked to a GM technician at
the local Chevy dealer, he said that on a '99 Old body style, the way
to fix it was to set the timing to zero degrees at 1500 RPM and the
DTC would "go away". Doesn't sound quite right to me.

As far as the crank position sensor being bad, the engine shouldn't
run if it was bad, right?

Ed