GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2004 🢒 TrailBlazer - 2WD 🢒 Engine 🢒 Engine Controls - 4.2L 🢒 Engine Cranks But Does Not Run

Description

The Engine Cranks but Does Not Run diagnostic table is an organized approach to identifying a condition that causes an engine not to start. The Engine Cranks but Does Not Run diagnostic table directs the service technician to the appropriate system diagnosis.

The Engine Cranks but Does Not Run diagnostic table assumes the following:

    • The battery is completely charged. Refer to Battery Inspection/Test in Engine Electrical.
    • The cranking speed is acceptable. Refer to Engine Cranks Slowly in Engine Electrical.
    • There is adequate fuel in the fuel tank.

Test Description

The number below refers to the step number on the diagnostic table.

  1. The crankshaft position (CKP) sensor can fail in such a way that will cause the engine to crank but will not run. The engine will be able to run by using the cam sensor when the CKP sensor is disconnected.

Step

Action

Value(s)

Yes

No

1

Did you perform the Diagnostic System Check-Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

  1. Turn ON the ignition, with the engine OFF.
  2. With a scan tool, observe the DTC information.

Does the scan tool display DTCs P0068, P0107, P0601, P0602, P0604, P0606, P0607, P0651, P1621, P1631, P1680, P1681, or P1682?

--

Go to Diagnostic Trouble Code (DTC) List

Go to Step 3

3

Does the scan tool display any body control module (BCM) vehicle theft deterrent (VTD) DTCs?

--

Go to Diagnostic Trouble Code (DTC) List in Theft Deterrent

Go to Step 4

4

Command the fuel pump ON with a scan tool.

Does the fuel pump turn ON?

--

Go to Step 5

Go to Fuel Pump Electrical Circuit Diagnosis

5
  1. Turn OFF the ignition.
  2. Remove an ignition coil. Refer to Ignition Coil Replacement .
  3. Install the J 26792 Spark Tester to the coil boot.
  4. Attempt to start the engine.

Does the spark tester spark?

--

Go to Step 6

Go to Electronic Ignition (EI) System Diagnosis

6
  1. Turn OFF the ignition.
  2. Disconnect the multi-way harness connector of the fuel injectors.
  3. Connect a test lamp between the ignition 1 voltage circuit of the fuel injector, fuse side, and a fuel injector control circuit, powertrain control module (PCM) side.
  4. Crank the engine.

Does the test lamp flash when cranking the engine?

--

Go to Step 7

Go to Fuel Injector Circuit Diagnosis

7
  1. Turn OFF the ignition.
  2. Install the J 34730-1A Fuel Pressure Gage. Refer to Fuel Pressure Gage Installation and Removal .
  3. Turn ON the ignition, with the engine OFF.
  4. Command the fuel pump ON with a scan tool.

Is the fuel pressure within the specified range while the fuel pump is operating?

334-375 kPa

(48-54 psi)

Go to Step 8

Go to Fuel System Diagnosis

8

  1. Disconnect the crankshaft position (CKP) sensor.
  2. Attempt to start the engine.

Does the engine start and continue to run?

--

Go to Step 10

Go to Step 9

9

Inspect for the following conditions:

    • A collapsed air intake duct
    • A restricted air filter element--Refer to Air Cleaner Element Replacement .
    • Contaminated fuel--Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • The spark plugs for being gas or coolant fouled--Refer to Spark Plug Inspection . If the spark plugs are fouled, determine what caused the condition.
    • An engine mechanical condition (worn timing chain, gears and low compression)--Refer to Symptoms - Engine Mechanical in Engine Mechanical.
    • A restricted exhaust system--Refer to Restricted Exhaust in Engine Exhaust.
    • An engine coolant temperature (ECT) sensor that has shifted in value. Refer to Temperature Versus Resistance .
    • Compare MAP/BARO parameters to another vehicle. The parameters should be close in value. Refer to DTC P0106 .

Did you complete the action?

--

Go to Step 11

--

10

Replace the CKP sensor. Refer to Crankshaft Position Sensor Replacement .

Did you complete the replacement?

--

Go to Step 11

Go to Step 2

11
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Attempt to start the engine.

Does the engine start and continue to run?

--

Go to Step 12

Go to Step 2

12
  1. Allow the engine to reach operating temperature.
  2. Observe the DTC information with a scan tool.

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK