Electronic Ignition (EI) System Diagnosis. Pontiac Grand Prix 2004

For 1990-2009 cars only

Makes 🢒 Pontiac 🢒 2004 🢒 Grand Prix 🢒 Brakes 🢒 Hydraulic Brakes 🢒 Electronic Ignition (EI) System Diagnosis

Circuit Description

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.

Step

Action

Values

Yes

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module Connector End Views

Did you perform the Diagnostic System Check-Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

Observe the Engine Speed parameter with a scan tool.
Crank the engine.

Does the scan tool indicate RPM is present?

Go to Step 3

Go to Crankshaft Position Sensor System Diagnosis

Observe the Cam Signal Present parameter with a scan tool.
Crank the engine.

Does the scan tool display Yes?

Go to Step 4

Go to Crankshaft Position Sensor System Diagnosis

Remove the fuel pump relay with the J 43244 Relay Puller Pliers.

Important: Ensure to ground the companion cylinder of the cylinder being tested

Test for spark at each cylinder with a J 26792 Spark Tester.

Did you have spark on all cylinders?

Go to Step 5

Go to Step 7

Does the spark tester indicate a bright blue spark on all cylinders?

Go to Step 6

Go to Step 7

Remove the spark plugs.
Examine the spark plugs for any abnormal conditions or damage. Refer to Spark Plug Inspection .

Are the spark plugs in good condition?

System OK

Go to Step 13

Turn OFF the ignition.
Connect the J 26792 to the spark plug wire of the inoperative cylinder.
Switch the inoperative spark plug wire connection with a known good cylinder at the ignition coils.
Crank the engine.

Do you have spark on the inoperative cylinder?

Go to Step 10

Go to Step 8

Disconnect the spark plug wires from the inoperative ignition coil.
Measure the secondary resistance of the ignition coil.

Is the resistance within the specified range?

5,000-8,000 ohms

Go to Step 9

Go to Step 15

Remove the inoperative ignition coil.
Connect a test lamp between the control circuits of the ignition coil on the ignition control module (ICM).
Crank the engine.

Does the test lamp turn ON and OFF while the engine is being cranked?

Go to Step 11

Go to Step 12

Test the spark plug wires for the following:

•	Proper routing and correct firing order--Refer to Ignition System Specifications .

•	Arching to ground

•	Proper resistance--Refer to Ignition System Specifications .

Important: If carbon tracking or corrosion is detected, replace both components that are affected.

•	Carbon tracking or corrosion

Did you find and correct the condition?

Go to Step 17

Go to Step 14

Test for an intermittent and for a poor connection at the ignition coil. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 15

Test for an intermittent and for a poor connection at the ICM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 16

Replace the spark plugs. Refer to Spark Plug Replacement .

Did you complete the replacement?

Go to Step 17

Replace the spark plug wires. Refer to Spark Plug Wire Replacement .

Did you complete the replacement?

Go to Step 17

Replace the ignition coil. Refer to Ignition Coil Replacement .

Did you complete the replacement?

Go to Step 17

Replace the ICM. Refer to Ignition Control Module Replacement .

Did you complete the replacement?

Go to Step 17

Turn the ignition OFF for 30 seconds.
Start the engine and operate the vehicle.
Observe the vehicle performance and driveability.

Does the vehicle operate normally?

System OK

Go to Step 3