GM Service Manual Online
For 1990-2009 cars only

Circuit Description

This engine is equipped with a non-distributor ignition system called the electronic ignition (EI) system. The primary circuit of the EI system consists of the following components:

    • Two separate ignition coils
    • An electronic ignition control module (ICM)
    • A crankshaft position (CKP) sensor
    • Related connecting wires
    • The ignition control (IC) portion of the powertrain control module (PCM)

Important: The camshaft position (CMP) sensor is only used for a misfire detection. It is not part of the ignition system.

Each secondary circuit consists of the following components:

    • The secondary winding of the coil
    • The spark plug wires
    • The spark plugs

Diagnostic Aids

Test or inspect for the following conditions:

    • A collapsed air intake duct
    • A restricted air filter element--Refer to Air Cleaner Element Replacement .
    • A throttle position (TP) sensor that reads too high or is skewed, which can cause an incorrect fueling condition
    • A TP sensor that is binding or is sticking in the wide open position
    • A TP sensor that is shorted or open
    • Contaminated fuel
    • No fuel
    • A restricted exhaust system--Refer to Restricted Exhaust in Engine Exhaust.
    • Low compression--Refer to Engine Compression Test in Engine Mechanical 2.4L.
    • A cold engine that has not been started should display engine coolant temperature (ECT) and intake air temperature (IAT) temperatures that are close to each other.
    • A skewed manifold absolute pressure (MAP) sensor--The MAP sensor value should change when you crank the engine. Compare any questionable barometer readings with barometer readings from a known good vehicle.
    • Check for proper idle air control (IAC) operation. Refer to Idle Air Control (IAC) System Diagnosis .
    • Check for intermittent conditions. Refer to Intermittent Conditions .

Test Description

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

  1. While cranking the engine, the CKP activity (CKP reference signal) should increment to 255, then rollover to 0.

Step

Action

Values

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 P0336, P0601, DTC P0602, P1621, P1626, P1630, P1631, or P1632.

--

Go to Diagnostic Trouble Code (DTC) List

Go to Step 3

3

With the scan tool, observe the CKP activity counter while cranking the engine.

Does the CKP activity counter increment while cranking the engine?

--

Go to Step 4

Go to Electronic Ignition (EI) System Diagnosis

4

  1. Turn ON the ignition, with the engine OFF.
  2. Important: Ensure the fuses below are not open, before proceeding with this test.

  3. Probe both sides of the following fuses with a test lamp to ground:
  4. • PCM
    • IGN MDL
    • F/P-INJ
    • BCM/CLUSTER

Does the test lamp illuminate on both sides of all the fuses?

--

Go to Step 5

Go to Testing for Short to Ground in Wiring Systems

5

With the scan tool, command the fuel pump ON.

Does the fuel pump run?

--

Go to Step 6

Go to Fuel Pump Electrical Circuit Diagnosis

6

  1. Turn OFF the ignition.
  2. Install a fuel gauge. Refer to Fuel Pressure Gage Installation and Removal .
  3. Turn ON the ignition, with the engine OFF.

Does the fuel pressure read within the specified value?

364-405 kPa (53-59 psi)

Go to Step 7

Go to Fuel System Diagnosis

7

  1. Turn OFF the ignition.
  2. Disconnect a fuel injector connector.
  3. Install a J 34730-405 fuel injector test lamp into the connector.
  4. Crank the engine.

Does the test lamp blink while cranking the engine?

--

Go to Step 8

Go to Fuel Injector Circuit Diagnosis

8

  1. Turn OFF the ignition.
  2. Remove the fuel pump relay.
  3. Remove the ignition coil/ignition control module (ICM) assembly.
  4. Important:: Not grounding the ICM assembly, may cause erratic spark.

  5. Install a jumper wire from the ICM assembly to ground.
  6. Install the J 36012-A spark plug jumper wire kit.
  7. Install a J 26792 spark tester on #1 spark plug jumper wire.
  8. Ground #4 (companion to #1) spark plug jumper wire.
  9. Crank the engine with the remaining spark plug jumper wires connected.
  10. Repeat the above steps by installing the spark tester on #4 and grounding #1. Do the same for #2 and #3 spark plugs. Making sure the companion wire is grounded.

Does the spark tester spark on all cylinders?

--

Go to Step 9

Go to Electronic Ignition (EI) System Diagnosis

9

  1. Turn OFF the Ignition.
  2. Inspect for malfunctioning spark plugs. Refer to Spark Plug Inspection .

Did you find and correct the condition?

--

Go to Step 10

Go to Diagnostic Aids

10

Attempt to start the engine.

Does the engine start and continue to run?

--

Go to Diagnostic System Check - Engine Controls

Go to Step 2