SB-10055840-5758

Service Bulletin

File in Section:

-

Bulletin No.:

PIP5168C

Date:

April, 2014

PRELIMINARY INFORMATION
Subject:

Crank No Start - Inspect for Sheared Cam Pin

Models:

2009-2014 Chevrolet Corvette, Camaro, Express, SS, Silverado, Suburban, Tahoe
2009-2014 GMC Savana, Sierra, Yukon
with a V8 engine (RPO Codes L20, L96, LMF, LMG, LS3, LY2, LY5, LY6)
This PI was superseded to correct model year listings. Please discard PIP5168B.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern
On rare occasions, a crank no start may be encountered on a cast iron V8 engine. Typically when this occurs, it is
generally when the vehicle still has low mileage, possibly during the Pre-Delivery inspection.
During diagnosis, the technician will find proper fuel pressure, spark from each spark plug wire, and proper injector
pulse. However, the following concerns will be noted during their diagnosis: low static compression, excessive
cylinder leakage past an intake or exhaust valve, the engine may start but run poorly if the CMP sensor is
disconnected, and/or the valve train may not move while cranking the engine.
This concern may be the result of a sheared camshaft sprocket locating pin due to the camshaft seizing to the
camshaft bearings at one time.

Recommendation/Instructions
If this concern is encountered, the following suggestions should be performed as necessary:
1. Crank the engine while checking for movement in the valve train. This can be done by shining light down the oil
fill tube on most models. If the valve train appears to be moving normally while the crankshaft is turning,
continue to step 2. But, if you determine valve train is not moving while the crankshaft is turning, continue to
step 4.
2. Disconnect the CMP sensor to see if the engine will start. If the engine starts, continue to step 4.
3. Perform the following SI diagnostic procedures as necessary:
– Engine Cranks But Does Not Run diagnosis in SI
– Engine Compression Test in SI (document results)
– Cylinder Leakage Test in SI (document results)
If the SI procedures above isolate an engine mechanical concern (low compression; excessive cylinder
leakage through the exhaust or intake, any type of valve train damage, etc.), continue to step 4.
4. If you have completed steps 1, 2, or 3, remove the front cover to inspect for a sheared cam sprocket locator pin.
Before removing the front cover, follow the latest version of 09-06-04-026 to verify the ECM calibrations just in
case engine replacement is necessary. If this is a new dealer stock unit, it is not necessary to verify the ECM
calibrations.
5. If you have determined the cam sprocket locator pin has sheared, replace the engine assembly.

Warranty Information
The correction for this concern may be one of several repairs described above. For vehicles repaired under warranty,
please use the appropriate warranty labor operation based on the actual cause and repair.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is
resolved without completing every step, the remaining steps do not need to be performed.