Electronic Ignition (EI) System Diagnosis. Pontiac Aztek

For 1990-2009 cars only

Makes 🢒 Pontiac 🢒 2001 🢒 Aztek - FWD 🢒 Engine 🢒 Engine Controls - 3.4L 🢒 Electronic Ignition (EI) System Diagnosis

Circuit Description

During cranking, the ignition control (IC) module monitors the 7X crankcase position (CKP) sensor input for recognition of the CKP 1 signal. The CKP 1 signal is used only by the IC module for synchronization at start-up to determine the correct cylinder pair to spark. Once the engine speed reaches approximately 600 RPM, the powertrain control module (PCM) sends 5.0 volts to the IC timing signal circuit at the IC module causing the IC timing control circuit to become ungrounded allowing the medium resolution engine speed signal to be used for better low engine speed performance. At higher engine speeds (1,650+) the PCM uses the low resolution engine speed signal to control ignition timing because a higher resolution signal is not needed.

In this ignition system, neither end of the secondary winding is grounded. Instead, each end of a coils secondary winding is attached to a spark plug. Each cylinder is paired with the cylinder that is opposite it (1-4, 2-5, 3-6). These two plugs are on companion cylinders, i.e., on top dead center at the same time. When the coil discharges, both plugs fire at the same time to complete the series circuit. The cylinder on compression is said to be the event cylinder and the one on exhaust is the waste cylinder. The cylinder on the exhaust stroke requires very little of the available energy to fire the spark plug. The remaining energy will be used as required by the cylinder on the compression stroke. The same process is repeated when the cylinders reverse roles. This method of ignition is called a waste spark ignition system.

This table assumes there are no ignition system, fuel injector, cam sensor, or crank sensor DTCs present. The electronic ignition system check tests for faulty ignition coils, spark plugs, plug wires, the 7X crank sensor, and IC module. This table requires the J 26792 spark tester.

Test Description

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

It is necessary to disconnect the 24X crank sensor to ensure that the 7X signal is being read in the 3X reference parameter on the scan tool.

The J 26792 presents a more difficult load on the secondary ignition than a normal spark plug. If a miss, stumble, or hesitation is being caused by a spark plug not firing, the spark tester should also not fire.

Use a 5 percent saltwater solution in a spray bottle to induce voltage arching to ground through faulty insulation of spark plug wires.

If the no spark condition follows the suspected coil, that coil is faulty. Otherwise, the ignition module is the cause of no spark. This test could also be performed by substituting a known good coil for the one causing the no spark condition.

Step

Action

Values

Yes

Schematic Reference: Engine Controls Schematics

Did you perform the Diagnostic System Check-Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

Attempt to start the engine

Does the engine start and continue to run ?

Go to Intermittent Conditions

Go to Step 3

Disconnect the 24X crank sensor.
With a scan tool, observe the 3X crank sensor parameter while cranking the engine.

Does the scan tool indicate 3X crank sensor signal present?

Go to Step 4

Go to Step 11

Reconnect the 24X crank sensor.
With a J 26792 spark tester, test for spark at each cylinder.

Did you observe any non-sparking cylinders?

Go to Step 5

Go to Step 8

Important: It is possible for an arching spark plug wire to IC module or arching ignition coil to IC module to cause a stall or no start condition.

Inspect and test the affected cylinder spark plug wires, ignition coils, and spark plugs for a short to ground or arching to ground. Refer to Spark Plug Wire Inspection .
If carbon tracking or corrosion is present, replace both components affected. Refer to Ignition Coil Replacement and Spark Plug Wire Replacement .

Did you find and correct the condition?

Go to Step 23

Go to Step 6

Test affected spark plug wires for proper resistance. Refer to Ignition System Specifications .
Replace spark plug wires not near specification. Refer to Spark Plug Wire Replacement .

Did you find and correct the condition?

3000 ohms per ft (9868 ohms per M)

Go to Step 23

Go to Step 7

Switch the affected cylinder coil with a known good one.
If the fault follows the affected coil, replace the coil. Refer to Ignition Coil Replacement .

Did you find and correct the condition?

Go to Step 23

Go to Step 15

Inspect the spark plug wires for proper routing and for the correct firing order. If any spark plug wires are found to be misrouted, reroute as necessary. Refer to Spark Plug Wire Inspection .

Did you find and correct the condition?

Go to Step 23

Go to Step 9

With a DMM, test spark plugs for internal short to ground. Refer to Spark Plug Inspection .
Replace any grounded spark plugs found. Refer to Spark Plug Replacement .

Did you find and correct the condition?

Go to Step 23

Go to Step 10

Remove the spark plugs. Refer to Spark Plug Replacement .
Inspect spark plugs for damage. Refer to Spark Plug Inspection .
If any spark plugs are found to be bad, replace the affected spark plugs. Refer to Spark Plug Replacement .

Did you complete the replacement?

Go to Step 23

Reconnect the 24X crank sensor.
Disconnect the IC module connectors.
Turn ON the ignition.
With a test lamp connected to a good ground, probe the IC module ignition 1 voltage circuit. Refer to Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp illuminate?

Go to Step 12

Go to Step 17

Connect a test lamp between the IC module ignition 1 voltage circuit and IC module ground circuit.

Does the test lamp illuminate?

Go to Step 13

Go to Step 20

Disconnect the 7X crankshaft sensor connector from the IC module.
With a test lamp connected to battery positive voltage, probe both the CKP sensor 1 signal (7X) and low reference (7X) circuits.

Does the test lamp illuminate when probing either circuits?

Go to Step 18

Go to Step 14

Connect a test lamp to ground.
Probe both the CKP sensor 1 signal (7X) and reference low (7X) circuits.

Does the test lamp illuminate when probing either circuit?

Go to Step 19

Go to Step 15

Ensure the battery voltage is within specifications.
Turn OFF the ignition.
Connect a DMM between the CKP sensor 1 signal circuit (7X) and the low reference (7X) circuit at the IC module harness connector.
Crank the engine while observing AC Duty Cycle percent .

Does the DMM indicate AC duty cycle present?

Go to Step 21

Go to Step 16

Test the 7X crank sensor circuits for the following conditions:

•

Opens

•	CKP sensor 1 signal and low reference (7X) circuits shorted together

Repair any damaged wiring. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 23

Go to Step 22

Repair the open or short to ground in the IC module ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems.
Replace the fuse if necessary.

Did you complete the repair?

Go to Step 23

Repair the short to ground in the circuit which illuminated the test lamp. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 23

Repair the short to voltage in the circuit which illuminated the test lamp. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 23

Repair the open in the IC module ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 23

Replace the IC module. Refer to Ignition Control Module Replacement .