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Category: Chevy
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Experience:  ASE certified tech ADVANCED LEVEL SPECIALIST. Wisconsin certified emissions state inspector
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1996 Chevy Impala SS: LT1..crank sensor..the wiring

Resolved Question:

1996 Chevy Impala SS LT1 missing on #2 and #3. Computer will set a PO336 but I have checked and changed the crank sensor. I continued and checked the wiring and changed the computer (pcm). Installed a new distributor plugs and wires. It appears that when you accelerate, the engine starts missing on the #2 and #3 cylinder. I installed new injectors on those cylinder monitored the spark with a inline light and used a noid light to monitor injector pulse. I performed a compression check. I have tried to identify any type of external vacuum leak and have not been able to find one. Any help would be greatly appreciated
Submitted: 6 years ago.
Category: Chevy
Expert:  AMEDEE replied 6 years ago.

Did you still need help?

Are you saying this code still comes up after all of the repairs that were made?
Customer: replied 6 years ago.
yes because the engine still misses under load
Expert:  AMEDEE replied 6 years ago.

Sorry for the delay!


I checked two different references for you for this code. This is what I got.


Code P0336- The camshaft position sensor signal was erratic when the engine was running.

The PCM calculates the difference in the 4X crank signal and the 24X signal to determine the 4X signal was erratic. The 4X signal was erratic for 1 second. Testing: Use a scan tool to check the crankshaft: for a signal to the PCM. The signal out of the sensor should be 4.0 to 6.0 volts AC with the engine cranking. This code sets when the signal has missing or extra pulses, so a lab scope is the best was to check the signal for noise or other problems.



P0336 DI Crankshaft Position Sensor Performance -


Possible Causes

CKP sensor connector has failed
Crankshaft reluctor wheel is damaged or improper installation
Distributor mechanical fault

Engine front cover damaged or timing gear is worn excessively
PCM has failed

THe best way to diagnose this is to use a lab scope to test for consistent 0 to 5 volt square wave pulses on the Red and Black wire and the Purple and White wire in the 4 wire test connector on the intake manifold while running. If inconsistent, test for stable 12 volts on the Red wire and ground on the Pink and Black wire.

If ok, check for harness chafing and loose terminals. If ok, the distributor is defective.


Potential Causes:


Crankshaft Position sensor Connector - Connections at Crankshaft Position (CKP) sensor.
Crankshaft Position Sensor Reluctor Wheel - Crankshaft reluctor wheel damage or improper installation.
Distributor - Excessive distributor drive backlash or other mechanical distributor problem.
Distributor Drive - Excessive distributor drive backlash.
Damaged Front Cover
Mis-Adjusted Sensor - The sensor coming in contact with the reluctor wheel.
Sensor Connector - Poor connections/terminal tension at the sensor.
Worn Timing Chain
Worn Timing Gear

Expert:  AMEDEE replied 6 years ago.

Also, here is what I got from alldata for this code.











The Crankshaft Position Sensor is mounted in the engine front cover assembly and works in conjunction with a 4X reluctor wheel 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 within the sensor. The sensors internal circuitry detects this and produces a signal which is read by the PCM. The PCM uses this signal to accurately measure crankshaft velocity which is a variable used to detect misfire. This sensor is not used for spark or fueling. For this diagnostic the PCM monitors the Crankshaft Position Sensor signal, and the Low Resolution and the High Resolution signals from the

distributor. During normal operation, at the falling edge of a Crankshaft Sensor signal pulse (signal voltage transitions to low)1 the PCM starts counting High Resolution pulses. The counter will increase until the PCM detects the leading edge of the next Low Resolution signal pulse (voltage transitions to high). The PCM monitors the number of High Resolution counts to verify proper CKP sensor operation. The scan tool parameter that displays the results of this calculation is CKP:Lo Resolution Angle. The value displayed is the number of degrees that the camshaft deviates [either advanced (+) or retarded (-)] from its normal alignment with the crankshaft. During normal operation, on a vehicle with little or no timing chain wear, the value displayed would be near 0 Deg.


Engine Speed between 500 and 4000 RPM (LT1), 675 and 4000 RPM (LT4)
Ignition Voltage between 9 and 17 volts
CKP:Lo Res Angle goes outside of the range from -10 Deg to +7 Deg but is still within the range -21 Deg to +51 Deg.


The PCM will illuminate the Malfunction Indicator Lamp (MIL) on the second consecutive drive trip that the diagnostic runs and fails.
The PCM will record operating conditions at the time the diagnostic tails. The first time the diagnostic fails, this information will be stored in Failure Records. It the diagnostic reports a failure on the second consecutive drive trip, the operating conditions at the time of failure will be written to Freeze Frame and the Failure record will be updated.


The PCM will turn the MIL OFF after three consecutive drive trips that the diagnostic runs and does not fail.
A last test failed (Current DTC) will clear when the diagnostic runs and does not fail.
A History DTC will clear after forty consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
PCM battery voltage is interrupted.
Using a Scan tool.

The following mechanical problems may cause this DTC to set:


Poor connections/terminal tension at the sensor.
Excessive timing chain/gear wear.
Excessive distributor drive backlash or other mechanical distributor problem.
Crankshaft reluctor wheel damage or improper installation.
Engine front cover assembly damage.
The sensor coming in contact with the reluctor wheel.
Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. It the DTC cannot be duplicated, the information included in the Freeze Frame and/or Failure Records data can be useful in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also be used to determine how many ignition cycles the diagnostic reported a pass and/or a tail.

Operate vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that were noted. This will isolate when the DTC tailed.

For intermittents, refer to Symptoms. See: Testing and Inspection


Number(s) below refer to step numbers on the diagnostic table.


Crankshaft RPM should be similar to Engine Speed within approximately + 75 RPM.
IMPORTANT: During hard acceleration these two parameters can differ widely from each other due to time variances in the PCMs internal calculating processes. This difference could show up in a snapshot. If other parameters indicate a hard acceleration condition, the difference in the two values should be disregarded.


It there is excessive timing chain/gear wear, the camshaft has a tendency to retard on acceleration and to advance on deceleration. This parameter will indicate a positive value as the crankshaft accelerates, then flip to a negative value as the crankshaft decelerates. This may be more apparent while driving the vehicle than it is under a no-load situation.
If the reluctor wheel keyway moves off of the key in the crankshaft before the damper hub is completely installed, it is possible to pinch the reluctor wheel in an incorrect position. This will cause the CKP:Lo Res Angle parameter to be skewed. If the distributor drive pin is not properly indexed into the distributor and then the distributor is drawn into place with the mounting bolts, the CKP:Lo Res Angle parameter will be skewed. Check the condition of the distributor shaft for evidence of this condition.
The parameter Cyl Mode Misfire Index is the difference in crankshaft deceleration from one reference period to the next (in counts). On a perfect engine this value would equal zero, however, due to normal variations in engine operation, a value less than 1000 is acceptable. In this diagnostic table, Cyl Mode Misfire Index is being used to detect erratic signals from the CKP sensor. The following conditions should be met before using this parameter:
Engine idling at normal operating temperature.
All accessories OFF.
No apparent engine misfire. DTC P0300 may or may not be set since that diagnostic relies on data from this sensor. If the engine is misfiring, this needs to be corrected before proceeding. refer to Symptoms. See: Testing and Inspection
With the signal generator set to 54mph, the Crankshaft RPM should indicate approximately 900 RPM.



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