GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 S10 Pickup - 2WD 🢒 Engine 🢒 Engine Controls - 2.2L (LN2) 🢒 Electronic Ignition (EI) System Diagnosis

Circuit Description

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

    • The low reference circuit
    • The low resolution engine speed signal circuit
    • The IC timing control circuit
    • The IC timing control B circuit

Diagnostic Aids
    • A small amount of resistance in the battery positive voltage to the PCM may cause a no start. Refer to Wiring Repairs in Wiring Systems.
    • The PCM grounds will cause a no start only if none of them are making a good connection. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
    • A loose CKP sensor may cause an intermittent no start by moving away from the reluctor wheel.

Test Description

The number below refers to the step number on the diagnostic table.

  1. Inspect for basic engine malfunctions, such as low compression, burnt valves, a worn timing chain and worn gears, etc.

Step

Action

Values

Yes

No

1

Did you perform the Diagnostic System Check-Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

Attempt to start the engine.

Does the engine start and run?

--

Go to Step 5

Go to Step 3

3

Is the ECM 1 fuse open?

--

Go to Step 23

Go to Step 4

4
  1. Crank the engine.
  2. Observe the CKP Active Counter parameter on the scan tool.

Does the CKP Active Counter parameter increment?

--

Go to Step 5

Go to Step 8

5
  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 to the spark plugs.
  4. Observe the J 26792 while cranking the engine.
  5. Repeat the procedure on cylinders 2, 3, and 4.

Does spark occur on all cylinders?

--

Go to Step 6

Go to Step 13

6
  1. Turn OFF the ignition.
  2. Inspect the spark plugs. Refer to Spark Plug Inspection .

Did you find a condition?

--

Go to Step 26

Go to Step 7

7

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

Did you find and correct the condition?

--

Go to Step 31

Go to Diagnostic Aids

8
  1. Turn OFF the ignition.
  2. Disconnect the IC module 2-pin connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the ignition 1 voltage circuit of the ICM to the ground circuit of the ICM at the harness connector with a DMM. Refer to Circuit Testing in Wiring Systems.

Does the voltage measure the specified value?

Battery Voltage

Go to Step 10

Go to Step 9

9

Measure the voltage from the ignition 1 voltage circuit of the IC and a good ground with a DMM.

Does the voltage measure the specified value?

Battery Voltage

Go to Step 24

Go to Step 25

10
  1. Disconnect the IC module 6-pin connector.
  2. Measure the resistance from the CKP sensor 1 signal circuit and the low reference circuit at the harness connector with a DMM. Refer to Circuit Testing in Wiring Systems.

Does the resistance measure within the specified range?

700-1,350ohms

Go to Step 11

Go to Step 17

11
  1. Crank the engine.
  2. Measure the frequency between the CKP sensor 1 signal circuit and the low reference circuit with a DMM. Refer to Circuit Testing in Wiring Systems.

Does the frequency measure within the specified range?

28-32 Hz

Go to Step 12

Go to Step 27

12
  1. Observe the CKP Activity Counter parameter on the scan tool.
  2. Momentarily touch a test lamp to the low resolution engine speed signal circuit connected to battery voltage.

Does the CKP Activity Counter increment?

--

Go to Step 21

Go to Step 19

13
  1. Disconnect the 6-pin ICM connector.
  2. Measure the AC voltage from the IC timing control circuit of the ICM and a good ground with a DMM. Refer to Circuit Testing in Wiring Systems.
  3. Crank the engine.

Is the voltage within the specified range?

1-3 V

Go to Step 14

Go to Step 15

14
  1. Measure the AC voltage from the IC timing control B circuit of the ICM and a good ground with a DMM. Refer to Circuit Testing in Wiring Systems.
  2. Crank the engine.

Is the voltage within the specified range?

1-3 V

Go to Step 20

Go to Step 16

15

Test the IC timing control circuit for the following conditions:

    • An open
    • A short to ground
    • A short to voltage
    • A short to the IC timing control B

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 31

Go to Step 22

16

Test the IC timing control circuit B for the following conditions:

    • An open
    • A short to ground
    • A short to voltage

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 31

Go to Step 22

17

Test the CKP sensor 1 signal circuit for the following conditions:

    • A faulty connection
    • An open
    • A short to ground
    • A short to voltage

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 31

Go to Step 18

18

Test the CKP sensor low reference circuit for the following conditions:

    • A faulty connection
    • An open
    • A short to ground
    • A short to voltage

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 31

Go to Step 27

19

Test the low resolution engine speed circuit for the following conditions:

    • A faulty connection
    • An open
    • A short to ground
    • A short to voltage

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 31

Go to Step 22

20
  1. Connect the ICM 6-pin connector.
  2. Exchange the ignition coil positions.
  3. Using the procedure in step 5 recheck for spark.

Does the no spark condition move with the coil?

--

Go to Step 28

Go to Step 21

21

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 conditions?

--

Go to Step 31

Go to Step 29

22

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

Did you find and correct the conditions?

--

Go to Step 31

Go to Step 30

23
  1. Repair the short to ground in the ignition 1 voltage circuit.
  2. Replace the fuse.

Is the action complete?

--

Go to Step 31

--

24

Repair the open in the ICM ground circuit.

Did you complete the repair?

--

Go to Step 31

--

25

Repair the open in the ignition 1 voltage circuit.

Did you complete the repair?

--

Go to Step 31

--

26

Replace the spark plugs. Refer to Spark Plug Replacement .

Did you complete the replacement?

--

Go to Step 31

--

27

Replace the CKP sensor. Refer to Crankshaft Position Sensor Replacement

Did you complete the replacement?

--

Go to Step 31

--

28

Replace the affected coil. Refer to Ignition Coil Replacement .

Did you complete the replacement?

--

Go to Step 31

--

29

Replace the ICM. Refer to Ignition Control Module Replacement .

Did you complete the replacement?

--

Go to Step 31

--

30

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

--

Go to Step 31

--

31
  1. Turn OFF the ignition for 30 seconds.
  2. Start the engine and operate the 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