Camaro, Firebird, 1999 - 2002

Distributorless Ignition System

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Adjustments



Ignition events are controlled by the PCM and are not manually adjustable.

Diagnosis & Testing



3.8L Engine

The Ignition Control Module (ICM) has independent power and ground circuits. The circuits between the ICM and the Powertrain Control Module (PCM) consists of the following circuits:



The Ignition Control (IC) timing signal
 
The IC timing control
 
The low resolution engine speed signal
 
The medium resolution engine signal
 
The camshaft position signal
 
The low reference
 

The ICM sends 3X signals to the PCM, and controls the timing advance during engine cranking. The timing advance changes to PCM control after the following actions occur:



The PCM receives the second 3X signal
 
The PCM applies 5 volts to the Ignition Control (IC) timing signal circuit.
 

The ICM monitors the CKP sync signal when the engine is cranking. The CKP sync signal is passed from the CKP sensor to the ICM on the CKP sensor 2 signal circuit. The CKP sync signal is used to determine the correct cylinder pair and initiate the ignition coil firing sequence. The 18X reference pulses are passed from the CKP sensor to the ICM on the CKP sensor 1 circuit. The 18X reference pulses are used for fuel injection and ignition control. After the ICM receives both signals, the ICM passes the 18X and 3X reference signals to the PCM. The CMP and the CKP sensors share a 12 volt reference and low reference circuit. The CKP sensor consists of the following circuits:



A 12 volt reference
 
A low reference
 
A CKP sensor 1 signal
 
A CKP sensor 2 signal
 

Diagnostic Aids

If the camshaft position signal is not present at start-up, the PCM will begin sequential fuel delivery with a 1 in 6 chance that fuel delivery is correct.

An intermittent may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation. Check for the following items:



Poor connection or damaged harness--Inspect the PCM harness and connectors for improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness.
 
Faulty engine coolant temperature (ECT)--Using a scan tool, compare engine coolant temperature with Intake Air Temperature (IAT) on a completely cool engine. The ECT should be within 10°C (50°F) of intake air temperature. If not, replace the ECT sensor.
 

5.7L Engine

The electronic ignition system uses an individual ignition coil for each cylinder. The Powertrain Control Module (PCM) controls the ignition operation through eight individual Ignition Control (IC) circuits. Each bank of four ignition coils is connected to the PCM, power, or ground by the following circuits:



Low reference
 
Chassis ground
 
Ignition 1 voltage
 
The appropriate IC circuit
 

The PCM triggers an ignition coil by grounding the appropriate IC circuit using information from the crankshaft position (CKP) and camshaft position (CMP) sensors.

Diagnostic Aids

Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.

For any test that requires probing the PCM or component harness connectors, use the Connector Test Adapter Kit . Using this kit prevents any damage to the harness connector terminals.

Using Freeze Frame/Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the condition, the information included in the Freeze Frame/Failure Records data can help determine how many miles since the condition occurred. Operate vehicle within the same freeze frame conditions, including the RPM, the load, the vehicle speed, and the temperature that you observed. This will isolate when the condition occurred.

Ignition Coil Pack



Removal & Installation
3.8L Engine
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Disconnect battery negative cable from battery and properly isolate to prevent accidental reconnection.
  4.  
  5. Disconnect the spark plug wires from the coil assemblies.
  6.  
  7. Remove 6 screws securing the coil assemblies to the ignition control module.
  8.  
  9. Remove the coils from the ignition control module.

    Click image to see an enlarged view

    Fig. Location and removal of ignition coil pack-3.8L engine

  10.  

To install:

  1. Attach the coils to the ignition control module.
  2.  
  3. Install 6 ignition coil attaching screws and tighten to 40 inch lbs. (4.5 Nm)
  4.  
  5. Connect the spark plug wires.
  6.  

5.7L Engine
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Disconnect battery negative cable from battery and properly isolate to prevent accidental reconnection.
  4.  
  5. Disconnect the spark plug wires from the coil assemblies.
  6.  
  7. Remove 6 screws securing the coil assemblies to the ignition control module.
  8.  
  9. Remove the coils from the ignition control module.

    Click image to see an enlarged view

    Fig. Location and removal of ignition coil pack-5.7L engine

  10.  

To install:

  1. Attach the coils to the ignition control module.
  2.  
  3. Install 6 ignition coil attaching screws and tighten to 40 inch lbs. (4.5 Nm)
  4.  
  5. Connect the spark plug wires.
  6.  
  7. Reconnect negative battery cable.
  8.  

 
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