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. Refer to Battery Inspection/Test in Engine Electrical. |
• | The engine cranking speed is within specification. Refer to Engine Cranks Slowly in Engine Electrical. |
• | There is adequate fuel in the fuel tank. |
Inspect for the following conditions:
• | The mass air flow (MAF) is compared to a calculated MAF based upon the manifold absolute pressure (MAP), the throttle position (TP), and the engine RPM. A skewed or unresponsive MAP sensor at key ON will cause the predicted air flow value to be inaccurate. Compare the MAP and TP readings to that of a known good vehicle. |
• | Inspect for a faulty engine coolant temperature (ECT) sensor. Use a scan tool in order to compare the ECT with the intake air temperature (IAT) on a completely cooled engine. The ECT should be within 3°C (5°F) of the IAT. |
• | For an intermittent condition, refer to Intermittent Conditions . |
The numbers below refer to the step numbers on the diagnostic table.
You may need to connect a battery charger to the battery for this step. If the battery state of charge is low, the scan tool may reset during the cranking test.
This step tests the ignition relay for proper operation. The ignition relay supplies voltage to the injectors and the ignition coils. When the ignition relay is not operating properly, a no start condition occurs. If the test lamp does not illuminate, this indicates the ignition relay is not suppling a voltage to the fuses.
Step | Action | Values | Yes | No | ||||||||||||
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Schematic Reference: Engine Controls Schematics | ||||||||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||||||||
2 | Crank the engine for the specified amount of time. Does the scan tool display any DTCs that failed this ignition? | 15 seconds | Go to Step 3 | |||||||||||||
3 | Inspect the body control module (BCM) for DTCs related to the vehicle theft deterrent (VTD) system. Does the scan tool display any BCM VTD DTCs? | -- | Go to Diagnostic System Check - Theft Deterrent in Theft Deterrent | Go to Step 4 | ||||||||||||
Monitor the engine speed while cranking the engine. Is engine RPM indicated on the scan tool? | -- | Go to Step 5 | ||||||||||||||
Does the test lamp illuminate on both sides of the fuses? | -- | Go to Step 6 | Go to Ignition Relay Diagnosis | |||||||||||||
6 | Monitor the engine coolant temperature (ECT) using the scan tool. Is the ECT on the scan tool close to the actual engine temperature? | -- | Go to Step 7 | Go to DTC P0118 | ||||||||||||
7 | Enable the fuel pump using the scan tool. Does the fuel pump operate? | -- | Go to Step 8 | |||||||||||||
8 |
Important: The fuel pump operates for about 2 seconds when the ignition is turned ON. The fuel pressure must be observed when the fuel pump is operating. Is the fuel pressure within the specified range? | VIN V,T, U Gasoline: 385-425 kPa (55-62 psi) VIN Z Ethanol: 335-375 kPa (48-54 psi) | Go to Step 9 | Go to Fuel System Diagnosis | ||||||||||||
9 | Perform the following additional inspections:
Did you find and correct the condition? | -- | Go to Step 10 | Go to Hard Start | ||||||||||||
10 |
Does the engine start and continue to run? | -- | Go to Step 11 | Go to Step 2 | ||||||||||||
11 |
Are any DTCs displayed? | -- | Go to Step 12 | |||||||||||||
12 | Select the Capture Info option and the Review Info option using the scan tool. Are any DTCs displayed that you have not diagnosed? | -- | System OK |