Refer to Engine Controls Schematics .
Circuit Description
The diagnosis for an engine that cranks but does not run must have 3 elements present before you proceed with the diagnostic table. The following conditions must exist:
| • | The battery must be adequately charged. |
| • | The engine cranking speed must be sufficient. |
| • | The amount of fuel in the fuel tank must be adequate. |
Diagnostic Aids
If you do not find a problem in the fuel pump circuit or in the ignition system and the cause of an Engine Cranks But Will Not Run has not been found, check the following conditions:
| • | Perform the Fuel Injector Solenoid Coil Test . |
| • | An after-market vehicle theft deterrent system could cause a start then stall or a no-start condition. |
| • | Fouled spark plugs |
| • | An EGR valve stuck open |
| • | Water or foreign material in the fuel system |
| • | A grounded or intermittently grounded ignition control (IC) signal circuit |
| • | A restricted exhaust system. Refer to Restricted Exhaust in Engine Exhaust. |
| • | Check the following ignition components: |
| - | A worn distributor cap |
| - | A worn distributor rotor |
| - | Check the ignition wires by lightly spraying them with water in order to identify intermittent no starts. |
Check the following mechanical components:
| • | The cylinder valve timing |
| • | A loose or broken timing chain |
| • | Low compression |
| • | Worn camshaft lobes |
| • | Bent or burned intake or exhaust valves |
The vehicle control module (VCM) has integrated circuits that are fault protected. If a circuit has failed, the integrated circuit may not be damaged. If that is the case, the system will keep the circuit open until the condition has been corrected.
Reinstall the VCM and check the circuit. Replace the VCM only if the circuit is still inoperative.
An intermittent may be caused by any of the following conditions:
| • | A poor connection |
| • | Rubbed through wire insulation |
| • | A broken wire inside the insulation |
Thoroughly inspect any circuitry that is suspected of causing the intermittent complaint. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Wiring Systems.
Test Description
The numbers below refer to the step numbers on the diagnostic tables.
-
If the engine starts, the problem could be intermittent. Basic engine mechanical problems, the vehicle theft deterrent (VTD) system, if the vehicle is so equipped, and faulty connections could cause a no-start condition.
-
This step will determine if the cause of the no-start condition or the start and stall condition is related to the VTD.
-
If the signal is more than 2.5 volts, the engine may be in the clear flood mode, which will cause starting problems.
-
If the engine coolant sensor temperature is less than -30°C (-22°F), the VCM provides fuel for this extremely cold temperature, and the fuel will severely flood the engine.
-
Use the spark plug tester tool in order to check the voltage at the spark plug. No spark indicates a basic ignition problem.
-
This test will determine if there is fuel pressure at the fuel injection unit and if the fuel pressure is holding steady.
-
Use the injector test lamp in order to test the injector circuits. A blinking lamp indicates that the VCM is controlling the injector.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 |
Important: Before clearing the DTCs, use the scan tool Capture info. to save the Freeze Frame/Failure Records for reference. The control modules data is deleted once you use the Clear Info function. Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
Attempt to start the engine. Does the engine start and continue to run? | -- | Go to Symptoms | ||
Does the VTD Fuel Disabled parameter display active while you crank the engine? | -- | Go to Diagnostic System Check - Theft Deterrent in Theft Deterrent | ||
Monitor the throttle position (TP) sensor on the scan tool. With the throttle closed, is the TP sensor more than the specified value? | 2.5 V | |||
Monitor the ECT sensor on the scan tool. Is the ECT sensor below the specified value? | -30°C (-22°F) | Go to DTC P0118 Engine Coolant Temperature (ECT) Sensor Circuit High Voltage | ||
Check for spark at 2 spark plug wires using the J 26792 spark tester. Is spark present at both of the spark plug wires? | -- | |||
Is the fuel pressure within the specified range? | 414-455 kPa (60-66 psi) | Go to Fuel System Diagnosis | ||
Does the injector test lamp flash for each injector circuit? | -- | Go to Diagnostic Aids |
