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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2001 🢒 Chevy C Cab/Chassis HD (GMT 400) 🢒 Body and Accessories 🢒 Cruise Control 🢒 Cruise Control Inoperative/Malfunctioning

Cruise Control Inoperative/Malfunctioning Diesel

Diagnostic Aids

Important: Perform the following in order to avoid misdiagnosis.

   • Inspect for proper operation of brake lamps and clutch switch, if equipped.
   • EMI on the speed sensor signal circuit may cause erratic cruise control operation.

Conditions for Enabling Cruise Control

The vehicle speed is greater than 40 km/h (25 mph).

Step

Action

Yes

No

Schematic Reference Cruise Control Schematics

1

Did you perform A Diagnostic System Check - Cruise Control?

Go to Step 2

Go to Diagnostic System Check - Cruise Control

2
  1. Connect a scan tool.
  2. Monitor the Cruise On switch parameter in the powertrain control module (PCM) data list.
  3. Turn ON the cruise control switch.

Did the scan tool parameter change state?

Go to Step 3

Go to Step 9

3
  1. Observe the cruise control Set/Coast parameter in the PCM data list.
  2. Press the cruise control Set button.

Did the cruise control Set/Coast parameter change state?

Go to Step 4

Go to Step 14

4
  1. Observe the cruise control Resume/Accelerate parameter in the PCM data list.
  2. Press the Resume/Accelerate switch.

Did the cruise control Resume Accelerate parameter change state?

Go to Step 5

Go to Step 15

5
  1. Observe the stop lamp switch parameter in the PCM data list.
  2. Press the brake pedal.

Did the stop lamp switch parameter change state?

Go to Step 6

Go to Step 10

6
  1. Observe the TCC/Brake switch parameter in the PCM data list.
  2. Press the brake pedal.

Did the cruise release switch parameter change state?

Go to Step 7

Go to Step 11

7

Is the vehicle equipped with a manual transmission?

Go to Step 8

Go to Step 29

8
  1. Observe the clutch pedal position (CPP) switch parameter in the PCM data list.
  2. Press the clutch pedal.

Did the CPP switch parameter change state?

Go to Step 29

Go to Step 12

9
  1. Turn OFF the ignition.
  2. Disconnect the multifunction turn signal lever.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the multifunction turn signal lever ignition positive voltage circuit with a test lamp connected to a good ground.

Did the test lamp illuminate?

Go to Step 13

Go to Step 21

10
  1. Turn OFF the ignition.
  2. Disconnect the stop lamp switch harness connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the stop lamp battery positive voltage feed circuit with a test lamp connected to a good ground.

Did the test lamp illuminate?

Go to Step 16

Go to Step 22

11
  1. Turn OFF the ignition.
  2. Disconnect the TCC/Brake switch harness connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the TCC/Brake switch ignition positive voltage circuit with a test lamp connected to a good ground.

Did the test lamp illuminate?

Go to Step 18

Go to Step 23

12
  1. Turn OFF the ignition.
  2. Disconnect the clutch pedal position (CPP) switch.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the CPP switch ignition positive voltage circuit with a test lamp connected to a good ground.

Did the test lamp illuminate?

Go to Step  20

Go to Step  24

13

Test the cruise control ON switch signal circuit for a open, high resistance, short to ground or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 35

Go to Step 28

14

Test the cruise control Set/Coast signal circuit for a open, high resistance, short to ground or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 35

Go to Step 28

15

Test the cruise control Resume/Accelerate signal circuit for a open, high resistance, short to ground or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 35

Go to Step 28

16

Test the stop lamp switch signal circuit for a open, high resistance, short to ground or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 35

Go to Step 17

17

Check the stop lamp switch for proper adjustment.

Did you find and correct the condition?

Go to Step 35

Go to Step 25

18

Test the TCC/Brake switch signal circuit for a open, high resistance, short to ground or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 35

Go to Step 19

19

Check the TCC/Brake switch for proper adjustment.

Did you find and correct the condition?

Go to Step 35

Go to Step 26

20

Test the CPP switch signal circuit for a open, high resistance, short to ground or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 35

Go to Step 27

21

Repair the open, high resistance or short to ground in the multifunction turn signal lever ignition positive voltage feed circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 35

--

22

Repair the open, high resistance or short to ground in the stoplamp switch battery positive voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 35

--

23

Repair the open, high resistance or short to ground in the TCC/Brake switch battery positive voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 35

--

24

Repair the open, high resistance or short to ground in the CPP switch battery positive voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 35

--

25

Inspect for poor connections at the harness connector of the stop lamp 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 35

Go to Step 30

26

Inspect for poor connections at the harness connector of the TCC/Brake 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 35

Go to Step 31

27

Inspect for poor connections at the harness connector of the CPP 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 35

Go to Step 32

28

Inspect for poor connections at the harness connector of the multifunction turn signal lever. 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 35

Go to Step 33

29

Inspect for poor connections at the harness connector of 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 35

Go to Step 34

30

Replace the stop lamp switch. Refer to Stop Lamp Switch Replacement in Hydraulic Brakes.

Did you complete the repair?

Go to Step 35

--

31

Replace the TCC/Brake switch. Refer to Stop Lamp Switch Replacement in Hydraulic Brakes.

Did you complete the repair?

Go to Step 35

--

32

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

Did you complete the repair?

Go to Step 35

--

33

Replace the multifunction turn signal lever. Refer to Multifunction, Turn Signal, and Hazard Switch Replacement - On Vehicle in Steering Wheel and Column - Tilt.

Did you complete the repair?

Go to Step 35

--

34

Important: The PCM must be reprogrammed after replacement. Refer to Powertrain Control Module Programming .

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

Did you complete the repair?

Go to Step 35

--

35

Operate the vehicle with in the conditions for cruise control operation.

Does the cruise control system operate properly?

System OK

Go to Step 2

Cruise Control Inoperative/Malfunctioning W/ETC

Diagnostic Aids

Important: Perform the following in order to avoid misdiagnosis.

   • Inspect for proper operation of brake lamps and clutch switch, if equipped.
   • EMI on the speed sensor signal circuit may cause erratic cruise control operation.

Conditions for Enabling Cruise Control

The vehicle speed is greater than 40 km/h (25 mph).

Step

Action

Yes

No

Schematic Reference: Cruise Control Schematics

1

Did you perform A Diagnostic System Check - Cruise Control?

Go to Step 2

Go to Diagnostic System Check - Cruise Control

2
  1. Turn OFF the ignition.
  2. Disconnect the Throttle Actuator Control (TAC) module.
  3. Turn ON the ignition, with the engine OFF.
  4. Turn OFF the cruise control switch.
  5. Probe the on/off, the set/coast, and the resume/accelerate circuits with a test lamp that is connected to a good ground.

Does the test lamp illuminate on any of the circuits?

Go to Step 16

Go to Step 3

3
  1. Turn ON the ignition, with the engine OFF.
  2. Turn ON the cruise control.
  3. Probe the on/off circuit with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 4

Go to Step 17

4
  1. Probe the set/coast circuit with a test lamp that is connected to a good ground.
  2. Press and hold the SET/COAST switch.

Does the test lamp illuminate?

Go to Step 5

Go to Step 19

5
  1. Probe the resume/accelerate circuit with a test lamp that is connected to a good ground.
  2. Press and hold the RESUME/ACCEL switch.

Does the test lamp illuminate?

Go to Step 6

Go to Step 20

6

Probe the stop lamp switch signal circuit with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 23

Go to Step 9

7

Press the brake pedal while monitoring the test lamp.

Does the test lamp illuminate?

Go to Step 8

Go to Step 21

8

Is the vehicle equipped with a manual transmission?

Go to Step 9

Go to Step 11

9
  1. Turn OFF the ignition.
  2. Disconnect the Powertrain Control Module (PCM).
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the clutch pedal position (CPP) switch signal circuit of the PCM harness connector with a test lamp connected to a good ground.

Does the test lamp illuminate?

Go to Step 10

Go to Step 14

10

Press the clutch pedal while monitoring the test lamp.

Does the test lamp illuminate?

Go to Step 27

Go to Step 11

11

Probe the TCC/brake switch signal circuit of the ECM harness connector with a test lamp connected to a good ground.

Does the test lamp illuminate?

Go to Step 12

Go to Step 15

12

Press the brake pedal while monitoring the test lamp.

Does the test lamp illuminate?

Go to Step 24

Go to Step 13

13

Check the speedometer for proper operation.

Does the speedometer operate properly?

Go to Step 34

Go to Symptoms - Instrument Panel, Gages and Console in Instrument Panel, Gages and Console

14
  1. Turn OFF the ignition.
  2. Disconnect the CPP switch.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the CPP switch ignition positive voltage circuit with a test lamp connected to a good ground.

Does the test lamp illuminate?

Go to Step 26

Go to Step 28

15
  1. Turn OFF the ignition.
  2. Disconnect the TCC/brake switch.
  3. Probe the TCC/brake switch ignition positive voltage circuit with a test lamp connected to a good ground.

Does the test lamp illuminate?

Go to Step 25

Go to Step 29

16

Test the circuit that illuminated the test lamp for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 40

Go to Step 33

17

Test the on/off signal circuit for a open, high resistance or short to ground and the S/C and R/A signal circuits for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 40

Go to Step 18

18

Test the ignition positive voltage circuit of the cruise control switch for a open, high resistance or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 40

Go to Step 33

19

Test the set/coast circuit for a open, high resistance or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 40

Go to Step 33

20

Test the resume/accelerate circuit for a open, high resistance or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 40

Go to Step 33

21

Test the stop lamp signal circuit for a open, high resistance or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 40

Go to Step 22

22

Test the stoplamp ignition positive voltage circuit for a open, high resistance or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 40

Go to Step 31

23

Test the stoplamp switch signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 40

Go to Step 31

24

Test the brake switch circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 40

Go to Step 31

25

Test the TCC/brake switch signal circuit of the PCM harness connector for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 40

Go to Step 32

26

Test the CPP signal circuit for a open, high resistance or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 40

Go to Step 30

27

Test the CPP signal circuit of the PCM harness for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 40

Go to Step 30

28

Repair the open in the ignition positive voltage circuit of the CPP switch.

Did you complete the repair?

Go to Step 40

--

29

Repair the open in the ignition positive voltage circuit of the stop lamp switch.

Did you complete the repair?

Go to Step 40

--

30

Inspect for poor connections at the harness connector of the CPP 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 40

Go to Step 35

31

Inspect for poor connections at the harness connector of the stop lamp 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 40

Go to Step 36

32

Inspect for poor connections at the harness connector of the TCC/brake 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 40

Go to Step 37

33

Inspect for poor connections at the harness connector of the cruise control 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 40

Go to Step 38

34

Inspect for poor connections at the harness connector of the Throttle Actuator Control (TAC) Module. 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 40

Go to Step 39

35

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

Did you complete the replacement?

Go to Step 40

--

36

Replace the Stop lamp switch. Refer to Stop Lamp Switch Replacement in Hydraulic Brakes .

Did you complete the replacement?

Go to Step 40

--

37

Replace the TCC/Brake switch. Refer to Stop Lamp Switch Replacement in Hydraulic Brakes.

Did you complete the replacement?

Go to Step 40

--

38

Replace the cruise control switch. Refer to Multifunction, Turn Signal, and Hazard Switch Replacement - On Vehicle in Steering Wheel and Column - Tilt.

Did you complete the replacement?

Go to Step 40

--

39

Replace the Throttle Actuator Control (TAC) Module. Refer to Electronic Throttle Actuator Control Module Replacement in Engine Controls.

Did you complete the replacement?

Go to Step 40

--

40

Operate the vehicle within the conditions for cruise control operation.

Does the cruise control system operate correctly?

System OK

Go to Step 2