GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2001 🢒 Sonoma Pickup - 2WD 🢒 Engine 🢒 Engine Controls - 2.2L (L43) 🢒 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.
    • A loose CKP sensor may cause an intermitted NO START by moving away from the reluctor wheel. Inspect the sensor and matting surface for being clean and tight.

Test Description

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

  1. Repair the cause of the malfunctioning spark plugs before replacing.

    2.

  2. Inspect for basic engine malfunction like low compression, burnt valves, a worn timing chain and worn gears, etc.

    3.

  3. Any time the CKP sensor is removed the crankshaft position variation learn procedure must be performed.

    4.

  4. The replacement PCM must be reprogrammed and the CKP system variation learn procedure must be performed.

Electronic Ignition Diagnosis

Step

Action

Value(s)

Yes

No

Schematic Reference: Engine Controls Schematics

1

Did you perform the Diagnostic System Check-Engine Controls?

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Go to Step 2

Go to Diagnostic System Check - Engine Controls

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

Does the CKP Activity Counter increment?

--

Go to Step   3

Go to Step 6

3
  1. Remove the fuel pump relay with the J 43244 Relay Puller Pliers.
  2. Install the J 26792 Spark Tester on cylinder #1 spark plug wires.
  3. Leave the other three ignition wires connected.
  4. Crank the engine and observe the spark tester for spark.
  5. Repeat the procedure on cylinders #2, #3, and #4.

Do all of the cylinders have spark?

--

Go to Step 4

Go to Step 10

4

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

Did you find and correct the condition?

--

Go to Step 23

Go to Step 5

5

Inspect for basic engine problems. Refer to Symptoms - Engine Mechanical in Engine Mechanical-2.2L (L43).

Did you find and correct any conditions?

--

Go to Step 23

Go to Diagnostic Aids

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

Does the voltage measure the specified value?

Battery Voltage

Go to Step 7

Go to Step 17

7
  1. Disconnect the ICM 6 pin connector.
  2. Measure the resistance between the CKP sensor 1 signal circuit and the CKP low reference circuit at the connector.

Does the resistance measure within the specified value?

700-1,350 ohms

Go to Step 8

Go to Step 11

8
  1. With the DMM still connected and set to the DC Hz scale.
  2. Crank the engine and observe the DMM.

Does the frequency measure within the specified value?

28-32 Hz

Go to Step 9

Go to Step 18

9
  1. Connect a test lamp to battery voltage.
  2. Momentarily touch the test lamp to the low resolution engine speed signal circuit, then touch the low reference circuit.
  3. Observe the CKP Activity Counter on the scan tool.

Does the CKP Activity Counter increment?

--

Go to Step 13

Go to Step 15

10
  1. Turn OFF the ignition.
  2. Disconnect the PCM connectors.
  3. Connect a J 26792 to the cylinder #1 spark plug wire, and a J 26792 to the cylinder #2 spark plug wire.
  4. Turn ON the ignition.

    5. Notice: Do not leave the jumper wire connected to the PCM IC circuit connector for longer than 5 seconds at a time. Failure to do so may damage the ignition coil and/or the Ignition Control Module.

  5. Connect a test lamp to battery voltage and momentarily touch both IC circuits at the PCM connector with the test lamp.

Does the spark tester spark on both wires?

--

Go to Step 14

Go to Step 16

11
  1. Inspect/Test the CKP sensor 1 signal circuit for the following conditions:
    2. • A faulty connection
    • An open circuit
    • A short to ground
    • A short to voltage
  2. If a problem is found, repair the condition as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 23

Go to Step  12

12
  1. Inspect/Test the CKP sensor 1 low reference circuit for the following conditions:
    2. • A faulty connection
    • An open circuit
    • A short to ground
    • A short to voltage
  2. If a problem is found, repair the condition as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 18

13
  1. Inspect for faulty connections at the ICM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. If a problem is found, repair the condition as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 23

Go to Step  20

14

  1. Inspect for faulty connections at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. If a problem is found, repair the condition as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 22

15
  1. Inspect/Test the low resolution engine speed circuit for the following conditions:
    2. • A faulty connection
    • An open
    • A short to ground
    • A short to voltage
  2. If a problem is found, repair the condition as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 22

16
  1. Test the affected IC timing control circuit for an open or a short.
  2. If a problem is found, repair the condition as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 21

17

Repair the open in the battery voltage and/or ground circuit.

Did you complete the repair?

--

Go to Step 23

--

18

Important:: 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 23

--

19

Switch ignition coil positions and recheck for spark.

Does the no spark move with the coil?

--

Go to Step 21

Go to Step 20

20

Replace the ICM. Refer to Ignition Control Module Replacement .

Did you complete the replacement?

--

Go to Step 23

--

21

Replace the affected ignition coil. Refer to Ignition Coil Replacement .

Did you complete the replacement?

--

Go to Step 23

--

22

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

--

Go to Step 23

--

23
  1. Turn ignition OFF for 30 seconds.
  2. Start engine and operate vehicle.
  3. Observe MIL, vehicle performance, and driveability.
  4. Does the vehicle operate normally, with no MIL illumination and no stored DTCs?

--

System OK

Go to Step 1