Engine Cranks but Does Not Run
Engine Cranks But Does Not Run
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
Circuit/System Description
This Engine Cranks but Does Not Run is an organized approach to identify a condition which causes the engine to crank but not start. This diagnostic directs the technician to the appropriate system diagnosis.
Diagnostic Aids
Inspect for any of the following conditions:
* When attempting to start the engine, the mechanical portion of the vehicle key must be locked in the fully extended position with the fob parallel to the key. Leaving the key partially retracted or folded over when starting may interrupt transponder authentication and result in an intermittent no-start condition. In such instances, DTC B3055 may also be set. If an intermittent no-start complaint is received, it may be necessary to discuss with the customer their starting habits and verify they are locking the key in the fully extended position, fob parallel to the key, before starting.
* Check the crankshaft position sensor engine reference signal with a scan tool. Observe the Engine Speed parameter while cranking the engine. The scan tool should indicate a steady 200-300 RPM while cranking. If erratic values, such as sudden spikes in the engine speed are displayed, the engine reference signal is not stable enough for the engine to start and run properly.
* The engine control module (ECM) uses the camshaft position sensors to determine engine speed and position when there is a crankshaft position sensor condition. If a crankshaft position sensor condition exists, the engine will operate only if the ECM has stored the learned reference position of the camshafts in ECM memory. With a crankshaft position sensor condition in the signal circuit, the engine will go into a limp home mode after a hard restart. The ECM then calculates engine speed from the camshaft position sensor.
* The fuel pump control module controls and monitors the operation of the in-tank fuel pump. If the fuel pump control module detects a fault, a DTC sets in the fuel pump control module. The fuel pump control module will then send a serial data message to the engine control module (ECM) requesting the illumination of the malfunction indicator lamp (MIL).
* Insufficient fuel can cause a no start condition. Thoroughly inspect the fuel delivery system for sufficient fuel volume to the fuel injectors. Inspect the fuel supply components for partial blockage or restrictions.
* Fuel injectors with partially blocked and restricted nozzles, or a malfunctioning solenoid, can cause a no start condition. Refer to Fuel Injector Solenoid Coil Test Fuel Injector Solenoid Coil Test.
* There may be fuel spray at the fuel injectors and the indicated fuel pressure may be correct, yet there may not be enough fuel to start the engine. If the fuel injectors and the injector circuit are OK, and fuel spray is detected, the fuel injector ON time may be inadequate. If the engine control module (ECM) receives incorrect inputs from the various information sensors, the fuel delivered by the fuel injectors may be inadequate to start the engine. Check all the engine data parameters with a scan tool and compare the values indicated with the expected values or the values from a known good vehicle.
* Inspect the engine for good secure electrical grounds.
* Water or foreign material in the fuel can cause a no start or engine will not stay running condition. During freezing weather water can freeze inside the fuel system. The engine may start after 30 min in a heated repair shop. The malfunction may not recur until parked overnight in freezing temperatures. Extreme weather conditions can cause contaminated fuel to prevent the vehicle from starting.
* A vehicle that starts and runs after being brought to the repair shop for a no start condition, may have an ignition system that is susceptible to moisture. Spray water on the ignition system components and the wiring in order to check for an engine starting or will not stay running concern.
Reference Information
Schematic Reference
Engine Controls Schematics [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Sunshade - Left
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
* Starting System Description and Operation Description and Operation
Scan Tool Reference
Control Module References Control Module References for scan tool information
Special Tools
J 26792 - HEI Spark Tester
For equivalent regional tools, refer to Special Tools Tools and Equipment.
Circuit/System Verification
Note: This diagnostic assumes the following:
* The battery is completely charged. See Battery Inspection/Test Battery Inspection/Test.
* The engine cranking speed is acceptable. refer to Engine Cranks Slowly Testing and Inspection.
* There is adequate fuel in the fuel tank.
1. Engine cranking, observe the scan tool DTC information. Verify that P0201-P0204, P0230, P0231, P0232, P023F, P025A, P0335, P0336, P0351-P0354, P0601, P0602, P0603, P0604, P0606, P0607, P060E, P062F, P0685, P0689, P0690, P069E, P1516, P1682, P2610, or P2635 is not set.
• If any of the DTCs are set
Refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle
• If no DTCs are set
2. Ignition ON.
3. Verify the security indicator on the instrument panel cluster illuminates momentarily.
• If the indicator stays illuminated or is flashing
Refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle and Immobilizer Description and Operation Immobilizer
• If the indicator does not stay illuminated or is not flashing
4. Verify the scan tool Engine Speed parameter is greater than 0 RPM while cranking the engine.
• If the Engine Speed parameter is 0 RPM
Refer to DTC P0335 or P0336 P0335 for further diagnosis.
• If the Engine Speed parameter is greater than 0 RPM
5. Ignition OFF.
6. Disconnect the T8 ignition coil from a cylinder and spark plug.
7. Connect a J 26792 - HEI Spark Tester between the boot of the ignition coil and ground.
Note: An erratic or weak spark is considered a no spark condition.
8. Verify that the spark tester sparks while cranking the engine.
• If the spark tester does not spark
Refer to Electronic Ignition System Diagnosis Electronic Ignition (EI) System Diagnosis for further diagnosis.
• If the spark tester does spark
9. Verify that the G12 fuel pump operation and fuel pressure are OK. Perform the Fuel System Diagnosis Fuel System Diagnosis.
• If the G12 fuel pump operation and pressure are not OK
Repair as necessary.
• If the G12 fuel pump operation and pressure are OK
10. Verify that the following conditions do not exist:
* Collapsed or restricted air intake duct to the throttle body
* Restricted air filter
* Gas or coolant fouled spark plugs
* A skewed manifold absolute pressure (MAP) sensor. Refer to DTC P0106 P0106
* A skewed engine coolant temperature (ECT) sensor. Refer to DTC P111E P111E
* A restricted exhaust system. Refer to Restricted Exhaust Restricted Exhaust.
* Contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis Testing and Inspection.
* An engine mechanical condition, for example, worn timing chain and gears or low compression. Refer to Symptoms - Engine Mechanical (LCV) Symptoms - Engine MechanicalSymptoms - Engine Mechanical (LTG) Symptoms - Engine Mechanical or Engine Compression Test Testing and Inspection
• If a condition is found
Repair as necessary.
• If a condition is not found
11. All OK
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
Spark Plug Replacement Service and Repair