GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Oldsmobile 🢒 2001 🢒 Alero 🢒 Engine 🢒 Engine Controls - 2.4L 🢒 Electronic Ignition (EI) System Diagnosis

Circuit Description

The ignition control (IC) module has independent power and ground circuits. The circuits between the IC module and the powertrain control module (PCM) consist of the following:

    • The low reference circuit
    • The low resolution engine speed signal
    • The two IC timing control signals
       - For cylinders 1 and 4
       - For cylinders 2 and 3

The IC module and PCM use the low resolution engine speed signal to control ignition operation. The low resolution engine speed signal is derived from the crankshaft position (CKP) sensor, which is connected directly to the IC module.

Diagnostic Aids
    • A small amount of resistance in the battery positive voltage circuit to the PCM may cause a no start. Test the battery positive voltage circuit for excessive resistance or corrosion. Refer to Wiring Repairs in Wiring Systems.
    • The PCM grounds will cause a NO START only if all of them are not making a good connection. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
    • If the CKP sensor is loose it may cause an intermitted NO START by moving away from the reluctor wheel. Inspect the sensor and matting surface for being clean and tight.

Electronic Ignition Diagnostic

Step

Action

Value(s)

Yes

No

Schematic Reference:

Power, Ground, KS, CMP, CKP Coils, and ICM


Object Number: 667497 Size: FS
Master Electrical Component List
Powertrain Control Module Description
Power, Ground, and Injectors
Power, Ground, MIL, and DLC
OBD II Symbol Description Notice
G103 and G105
IGN SW-BATT2, WIPER, AIR BAG, TURN LPS, IGN MOD, BU LMP, PCM IGN, F/PINJR, A/C BFC, AUTO TRANS, ABS, IGN Fuses

1

Did you perform the Diagnostic System Check-Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2
  1. Crank the engine.
  2. Observe the CKP Active Counter on the scan tool.

Does the CKP Active Counter increment?

--

Go to Step 3

Go to Step 6

3
  1. Turn OFF the ignition.
  2. Remove the Fuel Pump Relay with J 43244 relay puller pliers.
  3. Remove the Ignition Coil/Ignition Control Module (ICM) Assembly.

    4. Important:: Not grounding the ICM Assembly may cause erratic spark.

  4. Install a jumper wire from the ICM Assembly to ground.
  5. Install the J 36012-A spark plug jumper wire kit.
  6. Install a J 26792 spark tester on #1 spark plug jumper wire.
  7. Ground #4 (companion to #1) spark plug jumper wire.
  8. Crank the engine with the remaining spark plug jumper wires connected.
  9. 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 4

Go to Step 12

4
  1. Turn OFF the ignition.
  2. Inspect for malfunctioning spark plugs. Refer to Spark Plug Inspection .
  3. If a problem is found, repair as necessary.

Did you find and correct the condition?

--

Go to Step 30

Go to Step 5

5

Inspect for basic engine problems. Refer to Symptoms - Engine Mechanical in Engine Mechanical.

Did you find and correct any conditions?

--

Go to Step 30

Go to Step 25

6
  1. Turn OFF the ignition.
  2. Disconnect the ICM connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a DMM between the IC module ground circuit and the ICM ignition 1 voltage circuit at the connector.

Does the voltage measure near the specified value?

Battery Voltage

Go to Step 7

Go to Step 20

7

Connect the DMM between battery ground and the CKP sensor low reference circuit at the connector.

Does the DMM read voltage?

--

Go to Step 23

Go to Step 8

8

Use the DMM in order to measure the resistance between the battery ground and the CKP sensor low reference circuit at the connector.

Does the resistance measure infinity?

--

Go to Step 9

Go to Step 24

9

Measure the resistance between the CKP sensor low reference circuit and the CKP sensor 1 signal circuit at the connector.

Does the resistance measure within the specified value?

500-900 ohms

Go to Step 10

Go to Step 15

10
  1. With the DMM still connected and set to AC.
  2. Crank the engine and observe the DMM.

Does the voltage measure greater then the specified value?

1-1.3 Volts

Go to Step 11

Go to Step 26

11
  1. Connect a test lamp to battery voltage.
  2. Touch the test lamp to the CKP sensor 1 signal circuit, then touch the Low Reference circuit.
  3. Observe the CKP Active Counter on the scan tool.

Does the CKP Active Counter increment?

--

Go to Step 16

Go to Step 19

12
  1. Turn OFF the ignition.
  2. Remove the spark plug jumper wires.
  3. Remove the ignition coil housing. Refer to Ignition Coil Replacement .
  4. Disconnect the ignition coil connector from the ICM.
  5. Turn ON the ignition, with the engine OFF.
  6. Use a DMM in order to measure the coil ignition positive voltage circuit.

Does the voltage measure near the specified value?

Battery Voltage

Go to Step 13

Go to Step 16

13
  1. Connect a test lamp between battery voltage and the affected coil circuit at the ICM.
  2. Crank the engine.

Does the test lamp blink?

--

Go to Step 22

Go to Step 14

14
  1. Turn OFF the ignition.
  2. Disconnect the ICM connector.

    3. Important:: DO NOT use a test lamp in the next test.

  3. Connect a DMM between battery voltage and the affected IC Control circuit at the ICM connector.

Does the voltage measure near the specified value?

Battery Voltage

Go to Step 18

Go to Step 17

15
  1. Inspect the CKP sensor 1 signal circuit and CKP sensor low reference circuit for the following conditions.
    2. • Poor connection
    • Open
  2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 30

Go to Step 26

16
  1. Inspect the ICM connector for poor connections. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 30

Go to Step 27

17
  1. Inspect the IC control circuit for an open or poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 30

Go to Step 29

18
  1. Inspect the IC control circuit for an open or poor connection at the ICM. Refer to Wiring Repairs and Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. If a problem is found, repair as necessary.

Did you find and correct the condition?

--

Go to Step 30

Go to Step 27

19
  1. Test the CKP low reference circuit for the following conditions:
    2. • Poor connection
    • Open
    • Short to ground
    • Short to voltage
  2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems

Did you find and correct the condition?

--

Go to Step 30

Go to Step 29

20

Repair open in the ICM ground circuit and/or ignition voltage 1 circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 30

Go to Step 21

21

Repair short to ground in the coil control circuits.

Did you complete the repair?

--

Go to Step 30

--

22

Repair open or short to ground in the Jumper Harness between the ICM and the Coils. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 30

Go to Step 28

23

Repair the short to voltage in the CKP sensor 1 signal circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 30

--

24

Repair the short to ground in the CKP sensor 1 signal circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 30

--

25
  1. Refer to Diagnostic Aids for the following:
    2. • PCM grounds
    • Loose CKP sensor
  2. If a problem is found, repair as necessary.

Did you find and correct the condition?

--

Go to Step 30

--

26

Important:: The Crankshaft Position Variation procedure must be performed. Refer to Crankshaft Position System Variation Learn .

Replace the CKP sensor. Refer to Crankshaft Position Sensor Replacement .

Did you complete the replacement?

--

Go to Step 30

--

27

Replace the ICM. Refer to Ignition Control Module Replacement .

Did you complete the replacement?

--

Go to Step 30

--

28

Replace both Ignition Coils. Refer to Ignition Coil Replacement .

Did you complete the replacement?

--

Go to Step 30

--

29

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

--

Go to Step 30

--

30

Attempt to start the engine.

Does the engine start and continue to run?

--

Go to Step 31

Go to Step 2

31
  1. Turn the ignition OFF for 30 seconds.
  2. Start the engine and operate vehicle.
  3. Observe the MIL, vehicle performance, and driveability.

Does the vehicle operate normally, with no MIL illumination and no stored DTCs?

--

System OK

Go to Diagnostic Trouble Code (DTC) List