GM Service Manual Online
For 1990-2009 cars only

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Schematic Reference: Starting and Charging Schematics

Connector End View Reference: Master Electrical Component List in Wiring Systems

1

Did you perform the Diagnostic System Check for Engine Electrical?

Go to Step 2

Go to Diagnostic System Check - Engine Electrical

2

  1. Depress the clutch pedal or verify that the transmission is in Park or Neutral.
  2. Turn the ignition switch to the START position.

Does the engine crank?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

Is the security indicator flashing?

Go to Diagnostic System Check - Theft Deterrent in Theft Deterrent

Go to Step 4

4

  1. Depress the clutch pedal or verify that the transmission is in Park or Neutral.
  2. Cycle the ignition switch from the RUN to START position several times.

Does the PCM CONT relay click each time the ignition is placed in the START position?

Go to Step 5

Go to Step 8

5

  1. Turn OFF the ignition.
  2. Disconnect the PCM CONT relay.
  3. Connect a test lamp between the battery positive voltage circuit of the PCM CONT relay switch and a good ground.

Does the test lamp illuminate?

Go to Step 6

Go to Step 24

6

    Important: The engine may crank during this procedure.

  1. Depress the clutch pedal or verify that the transmission is in Park or Neutral.
  2. Connect a 30 amp fused jumper between the battery positive voltage circuit of the PCM CONT relay switch and the starter solenoid crank voltage circuit.

Does the engine crank?

Go to Step 18

Go to Step 7

7

Does the fuse in the jumper open?

Go to Step 25

Go to Step 16

8

  1. Turn OFF the ignition.
  2. Disconnect the PCM CONT relay.
  3. Turn On the ignition, with the engine Off.
  4. Connect a test lamp between the PNP/Clutch Start Switch Signal circuit of the PCM CONT relay coil and a good ground.
  5. Depress the clutch pedal or verify that the transmission is in Park or Neutral.
  6. Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

Go to Step 9

Go to Step 11

9

  1. Connect a test lamp between the PNP/Clutch Start Switch Signal circuit of the PCM CONT relay coil and the control circuit of the PCM CONT relay.
  2. Depress the clutch pedal or verify that the transmission is in Park or Neutral.
  3. Turn the ignition to the CRANK position.

Does the test lamp illuminate?

Go to Step 18

Go to Step 10

10

  1. Install the PCM CONT relay.
  2. With a scan tool, observe the Starter Relay - Low Volts parameter in the General Info - Outputs data list of the ECM.
  3. Depress the clutch pedal or verify that the transmission is in Park or Neutral.
  4. Turn the ignition to the CRANK position.

Does the scan tool display Test Fail?

Go to Step 26

Go to Step 17

11

Does the vehicle have an automatic transmission?

Go to Step 12

Go to Step 14

12

  1. Disconnect the Park/Neutral Position (PNP) switch.
  2. Connect a test lamp between the ignition 1 voltage circuit of the PNP switch and a good ground.
  3. Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

Go to Step 13

Go to Step 27

13

  1. Connect a 3 amp fused jumper between the PNP/Clutch Start Switch Signal circuit of the PCM CONT relay coil and the control circuit of the PCM CONT relay.
  2. Connect a test lamp between the ignition 1 voltage circuit of the PNP switch and the PNP/Clutch Start Switch Signal circuit.
  3. Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

Go to Step 20

Go to Step 28

14

  1. Disconnect the clutch start switch.
  2. Connect a test lamp between the ignition 1 voltage circuit of the clutch start switch and a good ground.
  3. Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

Go to Step 15

Go to Step 27

15

  1. Connect a 3 amp fused jumper between the ignition 1 voltage circuit of the PCM CONT relay coil and the control circuit of the PCM CONT relay.
  2. Connect a test lamp between the ignition 1 voltage circuit of the clutch start switch and the PNP/Clutch Start Switch Signal circuit.
  3. Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

Go to Step 22

Go to Step 28

16

Test the starter solenoid crank voltage circuit for a high resistance or open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 34

Go to Step 19

17

Test the PNP/Clutch Start Switch Signal circuit for a high resistance or open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 34

Go to Step 23

18

Inspect for poor connections at the PCM CONT relay. 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 34

Go to Step 29

19

Inspect for poor connections at the starter solenoid. 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 34

Go to Step 30

20

Inspect the PNP switch for proper adjustment. Refer to Park/Neutral Position Switch Adjustment in Automatic Transmissions - AF23-5 or Park/Neutral Position Switch Adjustment in Automatic Transmissions - VT25-E.

Did you find and correct the condition?

Go to Step 34

Go to Step 21

21

Inspect for poor connections at the harness connector of the PNP switch. 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 34

Go to Step 31

22

Inspect for poor connections at the harness connector of the clutch start switch. 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 34

Go to Step 32

23

Inspect for poor connections at the harness connector of the engine control module (ECM). 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 34

Go to Step 33

24

Repair the open or high resistance in the battery positive voltage circuit of the PCM CONT relay switch circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 34

--

25

Repair the short to ground in the starter solenoid crank voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 34

--

26

Repair the open or high resistance in the control circuit of the PCM CONT relay. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 34

--

27

Repair the open or high resistance in the ignition 1 voltage circuit of the PNP switch or clutch start switch. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 34

--

28

Repair the open or high resistance in the PNP/Clutch Start Switch Signal circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 34

--

29

Replace the PCM CONT relay.

Did you complete the replacement?

Go to Step 34

--

30

Replace the starter motor. Refer to Starter Motor Replacement .

Did you complete the replacement?

Go to Step 34

--

31

Replace the PNP switch. Refer to Park/Neutral Position Switch Replacement in Automatic Transmissions - AF23-5 or Park/Neutral Position Switch Replacement in Automatic Transmissions - VT25-E.

Did you complete the replacement?

Go to Step 34

--

32

Replace the clutch start switch. Refer to Clutch Pedal Position Switch Replacement in Clutch.

Did you complete the replacement?

Go to Step 34

--

33

Important: The replacement ECM must be programmed.

Replace the ECM. Refer to Engine Control Module Replacement in Engine Controls - 2.2L (L61).

Did you complete the replacement?

Go to Step 34

--

34

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2