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Makes 🢒 GMC_Truck 🢒 2002 🢒 GMC C-Series Medium Duty Truck B7 🢒 Engine 🢒 Engine Electrical 🢒 Starter Solenoid Does Not Click

Starter Solenoid Does Not Click 7.2L (LG5) Caterpillar Diesel

Step

Action

Yes

No

Schematic Reference: Starting and Charging Schematics

1

Did you preform the Engine Electrical Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Engine Electrical

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

Turn the ignition switch to the START position.

Does the starter motor relay click?

Go to Step 7

Go to Step 4

4
  1. Remove the starter motor relay.
  2. Connect a test light from the supply voltage circuit of the starter motor relay coil circuit to ground.
  3. With the transmission in park, neutral or the clutch pedal depressed, turn the ignition switch to the START position.

Does the test light illuminate?

Go to Step 5

Go to Step 6

5
  1. Connect a test light from the supply voltage circuit of the starter motor relay coil circuit to the control circuit of the starter motor relay coil circuit.
  2. With the transmission in park, neutral or the clutch pedal depressed, turn the ignition switch to the START position.

Does the test light illuminate?

Go to Step 13

Go to Step 10

6

Is the starter equipped with over crank protection (OCP) thermal switch?

Go to Step 7

Go to Step 8

7
  1. Turn OFF the ignition.
  2. Disconnect the starter therminal switch.
  3. Turn ON the ignition, with the Engine OFF.
  4. Connect a 10 amp fused jumper between the starter motor relay coil control circuits of the starter therminal switch.
  5. With the transmission in park, neutral or the clutch pedal depressed, turn the ignition switch to the START position.

Does the test lamp illuminate?

Go to Step 18

Go to Step 8

8
  1. Turn OFF the ignition.
  2. Disconnect the Park Neutral Position (PNP) switch Park/Neutral Backup Switch Replacement , Neutral Switch Allison for the Automatic Transmissions or the Clutch/Starter Interlock Switch Clutch Pedal Engine Start Switch Replacement for Manual Transmission.
  3. Turn ON the ignition, with the Engine OFF.
  4. Connect a 10 amp fused jumper between the starter motor relay coil control circuits of the PNP switch, Neutral Switch or Clutch/Starter Interlock Switch.
  5. With the transmission in park, neutral or the clutch pedal depressed, turn the ignition switch to the START position.

Does the test lamp illuminate?

Go to Step 16

Go to Step 13

9
  1. Turn OFF the ignition.
  2. Disconnect the starter motor relay.
  3. Connect a test lamp between the battery positive voltage circuit of the Starter Motor relay switch circuit and a good ground.

Does the test lamp illuminate?

Go to Step 10

Go to Step 19

10

Connect a 30 amp fused jumper between the battery positive voltage circuit of the starter motor relay switch circuit and the supply voltage circuit of the starter solenoid.

Does the engine crank?

Go to Step 15

Go to Step 11

11

Does the fuse in the jumper open?

Go to Step 20

Go to Step 14

12

Test the control circuit of the starter motor relay for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 25

Go to Step 21

13

Test the supply voltage circuit of the starter motor relay coil circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 25

Go to Step 17

14

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

Did you find and correct the condition?

Go to Step 25

Go to Step 18

15

Inspect for poor connections at the starter motor 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 25

Go to Step 21

16
    • If equipped with an Automatic Transmission, inspect for poor connection at the PNP switch, Neutral Switch Allison for the Automatic Transmissions harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. If OK, perform the Park/Neutral Backup Switch Adjustment (Allison) for automatic transmission.
    • If equipped with a Manual Transmission, inspect for poor connection at the Clutch/Starter Interlock Switch harness connector. 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 25

Go to Step 22

17

Inspect for poor connections at the ignition switch harness connector. 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 25

Go to Step 23

18

Inspect for poor connections at the starter thermal switch/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 25

Go to Step 24

19

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

Did you complete the repair?

Go to Step 25

--

20

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

Did you complete the repair?

Go to Step 25

--

21

Replace the Starter Relay. Refer to Relay Replacement in Wiring Systems.

Did you complete the replacement?

Go to Step 25

--

22

Replace the following switches:

    • PNP switch. Refer to Park/Neutral Backup Switch Replacement or Park/Neutral Backup Switch Replacement Allison in Automatic Transmission.
    • Clutch/Starter Interlock Switch. Refer to Clutch Pedal Engine Start Switch Replacement in Clutch.

Did you complete the replacement?

Go to Step 25

--

23

Replace the Ignition Switch. Refer to Ignition Switch Replacement - On Vehicle in Steering Wheel and Column.

Did you complete the replacement?

Go to Step 25

--

24

Replace the starter. Refer to Starter Motor Replacement .

Did you complete the replacement?

Go to Step 25

--

25

Operate the system for which the symptom occurred.

Did you correct the condition?

System OK

Go to Step 2

Starter Solenoid Does Not Click 8.1L (L18)

Step

Action

Yes

No

Schematic Reference: Starting and Charging Schematics

1

Did you preform the Engine Electrical Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Engine Electrical

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

Turn the ignition switch to the START position.

Does the starter motor relay click?

Go to Step 20

Go to Step 4

4
  1. Install a scan tool.
  2. With the scan tool observe the Crank Request Signal in the PCM data list.
  3. With the transmission in park, neutral or the clutch pedal depressed, turn the ignition switch to the START position.

Does the scan tool display Yes?

Go to Step 5

Go to Step 6

5
  1. Turn ON the ignition, with the Engine OFF.
  2. With the transmission in park or neutral observe the PNP Signal in the PCM data list.

Does the scan tool display Park/Neutral?

Go to Step 10

Go to Step 9

6

Is the starter equipped with over crank protection (OCP) terminal switch?

Go to Step 7

Go to Step 8

7
  1. Turn OFF the ignition.
  2. Disconnect the starter therminal switch.
  3. Turn ON the ignition, with the Engine OFF.
  4. Connect a 10 amp fused jumper between the starter motor relay coil control circuits of the starter therminal switch.
  5. With the transmission in park, neutral or the clutch pedal depressed, turn the ignition switch to the START position.

Does the engine crank?

Go to Step 20

Go to Step 8

8
  1. Turn OFF the ignition.
  2. If equipped with a manual transmission disconnect the Clutch/Starter Interlock Switch. Refer to Clutch Pedal Engine Start Switch Replacement .
  3. Turn ON the ignition, with the Engine OFF.
  4. Connect a 10 amp fused jumper between the starter motor relay coil control circuits Clutch/Starter Interlock Switch.
  5. With the transmission in park, neutral or the clutch pedal depressed, turn the ignition switch to the START position.

Does the scan toll display Yes for Crank Request Signal?

Go to Step 18

Go to Step 15

9
  1. Turn ON the ignition, with the Engine OFF.
  2. Disconnect the Neutral Switch.
  3. Connect a 10 amp fused jumper between the terminals of the Neutral Switch connector harness.
  4. With the transmission in park or neutral observe the PNP Signal in the PCM data list.

Does the scan tool display Park/Neutral?

Go to Step 18

Go to Step 13

10
  1. Turn OFF the ignition.
  2. Disconnect the starter motor relay.
  3. Connect a test lamp between the battery positive voltage circuit of the Starter Motor relay switch circuit and a good ground.

Does the test lamp illuminate?

Go to Step 11

Go to Step 22

11

Connect a 30 amp fused jumper between the battery positive voltage circuit of the starter motor relay switch circuit and the supply voltage circuit of the starter solenoid.

Does the engine crank?

Go to Step 17

Go to Step 12

12

Does the fuse in the jumper open?

Go to Step 23

Go to Step 16

13

Test the neutral switch signal and ground circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 29

Go to Step 28

14

Test the control circuit of the starter motor relay for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 29

Go to Step 24

15

Test the supply voltage circuit of the starter motor relay coil circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 29

Go to Step 19

16

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

Did you find and correct the condition?

Go to Step 29

Go to Step 20

17

Inspect for poor connections at the starter motor 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 29

Go to Step 24

18

If equipped with a Manual Transmission inspect for poor connection at the Clutch/Starter Interlock Switch harness connector. 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 29

Go to Step 25

19

Inspect for poor connections at the ignition switch harness connector. 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 29

Go to Step 26

20

Inspect for poor connections at the starter therminal switch/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 29

Go to Step 27

21

Inspect for poor connections at the PCM. 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 29

--

22

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

Did you complete the repair?

Go to Step 29

--

23

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

Did you complete the repair?

Go to Step 29

--

24

Replace the starter motor relay.

Did you complete the replacement?

Go to Step 29

--

25

Replace the Clutch/Starter Interlock Switch. Refer to Clutch Pedal Engine Start Switch Replacement in Clutch.

Did you complete the replacement?

Go to Step 29

--

26

Replace the Ignition Switch. Refer to Ignition Switch Replacement - On Vehicle in Steering Wheel and Column.

Did you complete the replacement?

Go to Step 29

--

27

Replace the starter. Refer to Starter Motor Replacement .

Did you complete the replacement?

Go to Step 29

--

28

Important: The replacement PCM must be programmed.

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls-8.1L.

Did you complete the repair?

Go to Step 29

--

29

Operate the system for which the symptom occurred.

Did you correct the condition?

System OK

Go to Step 2