GM Service Manual Online
For 1990-2009 cars only

Circuit Description

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

Inspect for leaks in the intake air ducting between the mass airflow (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

Important: If the ignition main relay fails to close, the vehicle will crank but will not run.

Does the scan tool display DTCs P0036, P0412, P0418, P0443, P0449, P1546, P1689, and U1040?

--

Go to Ignition Relay Diagnosis

Go to Step 3

3

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

Does the scan tool display DTCs P0201-P0206, P0230, P0335, P0340, P0385, P0403, P0404, P0601, P0602, P1351-P1356, P1361-P1366, and P1404?

--

Go to Diagnostic Trouble Code (DTC) List

Go to Step 4

4

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

Is the fuse open?

--

Go to Electronic Ignition (EI) System Diagnosis

Go to Step 5

5

With a scan tool, command the fuel pump ON.

Does the fuel pump turn ON?

--

Go to Step 6

Go to Fuel Pump Electrical Circuit Diagnosis

6

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

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

333-380 kPa

(48-55 psi)

Go to Step 7

Go to Fuel System Diagnosis

7

  1. Turn OFF the ignition.
  2. Disconnect an injector connector from each cylinder bank.
  3. Install theJ 34730-405 to the injector connector.
  4. Attempt to start the engine.

Does the test lamp blink on both engine banks while the engine is cranking?

--

Go to Step 8

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

8

Inspect for the following conditions:

    • A collapsed air intake duct.
    • A 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 .
    • An engine mechanical condition such as a worn timing chain and gears, or low compression-- Refer to Engine Compression Test in Engine Mechanical.
    • A restricted exhaust system--Refer to Restricted Exhaust in Engine Exhaust.

Did you find and correct the condition?

--

Go to Step 9

Go to Diagnostic Aids

9

  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 10

Go to Step 2

10

  1. Idle the engine.
  2. Allow the engine to reach the 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 11

11

With a scan tool, review 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