GM Service Manual Online
For 1990-2009 cars only

Circuit Description

To start the engine the correct air/fuel mixture must be compressed within the cylinder, and sparked at the proper time. This assumes that the vehicle battery condition and cranking speed is within specifications, and that an adequate amount of quality fuel is in the tank. The powertrain control module (PCM) controls fuel delivery, fuel metering, and spark timing. When the key is first turned ON, the PCM energizes the fuel pump to prime the fuel rail assembly. The PCM uses input from various information sensors to determine the correct amount of fuel to mix with the intake air, and the spark timing of the mixture over a wide range of starting conditions.

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.

To prevent mis-diagnosis, perform Diagnostic System Check - Engine Controls before performing this table.

Unless the engine enters Clear Flood at the first indication of a flooding condition, a no start may result. Be sure to check the spark plugs for signs of fouling.

Inspect for leaks in the intake air ducting between the mass air flow (MAF) sensor and the throttle body.

If the steps above check OK, refer to Hard Start for diagnosis.

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 DTC P0201-P0208, P0230, P0335, P0340, P0385, P0403, P0404, P0601, P0602, P1359, P1360, P1404?

--

Go to Diagnostic Trouble Code (DTC) List

Go to Step 3

3

Inspect the fuse that supplies ignition voltage to the ignition coil cassettes.

Is the fuse open?

--

Go to Electronic Ignition (EI) System Diagnosis

Go to Step 4

4

With a scan tool, command the fuel pump relay ON.

Does the fuel pump relay turn ON?

--

Go to Step 5

Go to Fuel Pump Electrical Circuit Diagnosis

5

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

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

284-325 kPa

(41-47 psi)

Go to Step 6

Go to Fuel System Diagnosis

6

  1. Turn OFF the ignition.
  2. Disconnect an injector connector from each cylinder bank.
  3. Install the injector test lamp to the injector connector.
  4. Attempt to start the engine.

Does the test lamp blink while the engine is cranking?

--

Go to Step 7

Go to DTC P0201, P0202, P0203, P0204, P0205, P0206, P0207, or P0208

7

Inspect for the following conditions:

    • Collapsed air intake duct
    • Restricted air filter element--Refer to Air Cleaner Element Replacement .
    • Spark plugs for being gas or coolant fouled. If the spark plugs are fouled, determine what caused the condition. Refer to Spark Plug Inspection .
    • Engine mechanical condition (worn timing chain and gears, low compression, etc.). Refer to Engine Compression Test in Engine Mechanical.
    • Restricted exhaust system. Refer to Restricted Exhaust in Engine Exhaust.

Did you find and correct the condition?

--

Go to Step 8

Go to Diagnostic Aids

8

  1. With a scan tool, clear the DTCs.
  2. Attempt to start the engine.

Does the engine start and continue to operate?

--

Go to Step 9

Go to Step 2

9

  1. Idle the engine.
  2. Allow the engine to reach operating temperature.
  3. With a scan tool, observe the DTC information.

Are any DTCs displayed?

--

Go to Diagnostic Trouble Code (DTC) List

Go to Step 10

10

With a scan tool, observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK