Engine Cranks But Does Not Run
Engine Cranks but Does Not RunDescription
The Engine Cranks but Does Not Run diagnostic table is an organized approach to identifying a condition that causes an engine to not start. The diagnostic table directs the service technician to the appropriate system diagnosis. The diagnostic table assumes the following conditions are met:
- The battery is completely charged and terminals are cleaned and tight.
- The engine cranking speed is normal.
- There is adequate fuel in the fuel tank.
- There is no air in the fuel line.
- Filters (Air, Fuel) are clean.
NOTE: The engine will start even if exhaust brake is fully engaged.
Diagnostic Aids
If an intermittent condition is suspected, the following may cause an intermittent:
- Poor connections.
- Misrouted harness.
- Rubbed through wire insulation.
- Broken wire inside the insulation.
Check for the following conditions:
- Poor connection at engine control module (ECM): Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.
Test Description
The numbers below refer to the step number on the diagnostic table.
4. If the suction control valve (SCV) low control circuits between the ECM and the SCV are shorted to ground, "Actual Suction Control Valve Control Current" will be dropped approximately 500 mA as compared with "Desired Suction Control Valve Control Current".
Engine Cranks but Does Not Run
Schematic Reference: Engine Controls Schematics
