GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2000 🢒 Seville 🢒 Engine 🢒 Engine Controls - 4.6L 🢒 Engine Cranks But Does Not Run

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 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

To prevent mis-diagnosis, perform the Powertrain OBD System Check 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.

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

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 the 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 .

Test Description

The numbers below refer to the step numbers on the diagnostic table:

  1. Checks for proper fuel pressure to the fuel rail assembly.

    2.

  2. The fuel system pressure test will locate the cause of fuel pressure that is below specifications. However, if no fuel pressure is available, the fuel pump may be faulty.

    3.

  3. If the engine does not enter Clear Flood Mode at the first indication of a flooding condition, a no start condition may occur due to excess fuel fouling the spark plugs.

    4.

  4. A faulty splice connection in the underhood fuse block assembly will interrupt the ignition voltage supply to both ignition module assemblies.

Engine Cranks But Will Not Run

Step

Action

Values

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

Important: Before proceeding with this diagnostic table, ensure that the following conditions are met:

   • The battery condition has been tested.
   • The battery is fully charged.
   • An adequate amount of fuel is in the tank.

Is DTC P0335, P0340, and P0385 set?

--

Go to Step 3

Go to Step 4

3

Locate and repair the short between ground and the following circuits:

    • CKP Sensor A Ignition Feed
    • CKP Sensor B Ignition Feed
    • CMP Sensor Ignition Feed
    • Shorted CKP or CMP components

Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 12

--

4

Important: If any other DTCs are stored as failed since code clear, diagnose the DTCs before continuing with this table.

  1. Check the fuses that supply ignition positive voltage to the following components:
    2. • Each ignition control assembly
    • Fuel injectors
  2. If any of the fuses are blown, locate and repair the short to ground or shorted component in the affected ignition positive voltage circuit.

Was a problem found?

--

Go to Step 12

Go to Step 5

5
  1. Using the scan tool check for the following conditions:
    2. • Scewed TP sensor
    • Scewed ECT sensor
    • Scewed or unresponsive MAP sensor
  2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 12

Go to Step 6

6

  1. Turn the ignition to the LOCK position.
  2. Install a fuel pressure gauge at the fitting on the fuel rail.
  3. Turn the ignition to the RUN position.
  4. Observe the fuel pressure gauge.

Is the fuel pressure within the specified values?

284-325 kPa (41-47 psi)

Go to Step 8

Go to Step 7

7

Is any fuel pressure indicated?

--

Go to Fuel System Pressure Test

Go to Fuel Pump Circuit Diagnosis

8
  1. Check for a malfunctioning Mass Air Flow (MAF) sensor.
  2. If a problem is found, replace the MAF sensor. Refer to Mass Airflow Sensor/Intake Air Temperature Sensor Replacement .

Was a problem found?

--

Go to Step 12

Go to Step 9

9

  1. Check for fouled spark plugs.
  2. If a problem is found, replace the spark plugs. Refer to Spark Plug Replacement in Engine Electrical.

Was a problem found?

--

Go to Step 12

Go to Step 10

10

  1. Check for a faulty splice connection in the battery positive feed circuit to both ignition control module assemblies.
  2. If a problem is found, repair as necessary. Refer to Connector Repairs or Wiring Repairs in Wiring Systems.

Was a problem found?

--

Go to Step 12

Go to Step 11

11
  1. Check for an engine mechanical problem. Refer to Base Engine Misfire Diagnosis in Engine Mechanical.
  2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 12

Go to Hard Start

12
  1. Clear any DTCs.
  2. Attempt to start the engine.

Does the engine start and run?

--

Go to Step 13

Go to Step 2

13
  1. Allow the engine to idle until normal operating temperature is reached.
  2. Using the scan tool, check for any DTCs.

Does the scan tool indicate any DTCs that failed this ignition?

--

Go to the applicable DTC

System OK