Diagnostic Aids
WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
If the cause of an engine cranks but will not run condition has not been found, inspect for the following conditions:
- Hard starting only in cold ambient temperatures.
- The correct cranking speed is 100 RPM cold and 180 RPM hot. A scan tool can be used to inspect cranking speed by pulling the ignition 1 relay and monitoring engine speed on scan tool while cranking.
- Water or foreign material in fuel system.
- A basic engine problem.
- If CKP sensor and CMP sensor are disconnected or malfunctioning at the same time, an engine cranks but does not run condition will exist.