GM Service Manual Online
For 1990-2009 cars only

Description

This table assumes that the battery condition and the engine cranking speed are OK. If not, refer to Starting System Check for diagnosis. Also, make sure that there is adequate fuel in the tank.

Diagnostic Aids

Notice: Use the connector test adapter kit J 35616-A for any test that requires probing the following items:

   • The PCM harness connectors
   • The electrical center fuse/relay cavities
   • The component terminals
   • The component harness connector
Using this kit will prevent damage caused by the improper probing of connector terminals.

    • Unless the engine enters Clear Flood at the first indication of a flooding condition, a no start may result.
    • Check the duct work between the Mass Air Flow (MAF) sensor and the throttle body for air leaks.
    • A malfunctioning MAF sensor may cause a no start or a stall after start. If this is suspected, disconnect the MAF sensor. The PCM will ignore the MAF sensor and default to calculated air flow. If this corrects the condition and the connections are OK, replace the MAF sensor.
    • If the steps above check OK, refer to Hard Start in Symptoms for diagnosis.
    • If the problem is intermittent, refer to Intermittent Conditions .

Test Description

The number(s) below refer to step numbers on the diagnostic table.

  1. These DTCs are for systems/components which if operating improperly may cause a no-start.

  2. If the fuel pump is not audible at the fuel tank area, listen underhood at the fuel rail. Fuel flowing through the pressure regulator produces an audible hiss.

  3. The Fuel System Pressure Test contains the correct procedures and specifications for checking the fuel pressure. If a problem is found, continue diagnosis in the Fuel System Pressure Test.

  4. Hard Start in Symptoms contains more detailed information as well as additional diagnostic aids.

  5. Recheck the system for any multiple problems that may be related (for example, fouled spark plugs that were caused by a fuel system problem). Certain engine mechanical problems such as incorrect cam timing, low compression etc., could cause the engine to crank but not start. If this is suspected, refer to Engine Compression Test in Engine Mechanical.

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

Check for any DTCs with the scan tool.

Are any of the following DTCs displayed: P0230, P0335, P0385, P0560, P0601, P0602, P1404, P1610, P1626, P1631, P1635, P1639?

--

Go to the applicable DTC table

Go to Step 3

3

Check the fuse(s) that supply power to the Fuel Injectors and the Ignition Control Modules.

Is a fuse open?

--

Go to Step 11

Go to Step 4

4

Check the Engine Coolant Temperature with the scan tool.

Is the Engine Coolant Temperature on the scan tool close to the actual engine coolant temperature?

--

Go to Step 5

Go to Step 9

5

Check the TP Angle with the scan tool.

Is the TP Angle greater than the value specified at closed throttle?

2%

Go to Step 10

Go to Step 6

6

Turn the ignition to Off and wait 15 seconds. Turn the ignition On. The PCM should enable the fuel pump for about 2 seconds.

The fuel pump can also be enabled using the scan tool.

Does the fuel pump operate?

--

Go to Step 7

Go to Fuel System Diagnosis .

7

  1. Turn off the ignition.
  2. Install a fuel pressure gauge and check the fuel pressure. Refer to Fuel System Pressure Test for the correct procedures and specifications.

Was a problem found?

--

Go to Fuel System Diagnosis .

Go to Step 8

8

Perform the following additional checks:

    • Unless the engine enters Clear Flood at the first indication of a flooding condition, a no start may result. Check for fouled spark plugs.
    • Check all of the duct work between the Mass Air Flow (MAF) sensor and the throttle body for air leaks.
    • A malfunctioning MAF sensor may cause a no start or a stall after a start. If this condition is suspected, disconnect the MAF sensor. The PCM will ignore the MAF sensor and default to the calculated air flow. If this corrects the condition and the connections are OK, replace the MAF sensor.
    • Check for an injector pulse at the fuel injectors using Injector Test Light J 34730-405. An actual injector circuit failure will set an injector circuit DTC. If there is no injector pulse and no injector DTC is set, replace the PCM (this is an extremely unlikely failure).

Was a problem found and corrected?

--

Go to Step 12

Go to Hard Start in Symptoms , for diagnosis

9

Check for a mis-scaled ECT sensor.

If the vehicle is completely cool (overnight), the ECT and the IAT should be within a few degrees of each other.

The sensor can also be checked using the Temperature vs Resistance table.

Is the action complete?

--

Go to Step 12

--

10

Check for a mis-scaled TP sensor.

TP Angle should be near 0% at closed throttle and 100% at WOT and increase smoothly as the throttle is slowly opened. If TP Angle is not indicating closed throttle with no pressure on the accelerator pedal, check for a sticking or binding mechanism and correct as neccessary. If a spike or dropout occurs while sweeping the TP sensor through its operating range, check the connections at the sensor. If the connections are OK replace the sensor.

For additional information, refer to DTC P0121.

Is the action complete?

--

Go to Step 12

--

11

  1. Locate and repair the short that caused the fuse to open. Refer to General Electrical Diagnosis .
  2. Replace the fuse.

Is the action complete?

--

Go to Step 12

--

12

  1. Clear the DTCs with the scan tool.
  2. Attempt to start the engine.

Does the engine start and continue to run?

--

Go to Step 13

Refer to Test Description .

13

  1. Allow the engine to idle until normal operating temperature is reached.
  2. Check for any DTCs with the scan tool.

Are there any DTCs displayed?

--

Go to the applicable DTC table

Go to Step 14

14

Were there any additional DTCs noted during the Powertrain OBD System Check that have not been diagnosed?

--

Go to the applicable DTC table

The System is OK