GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2003 🢒 Escalade 🢒 Body and Accessories 🢒 Cruise Control 🢒 Cruise Control Inoperative/Malfunctioning

Diagnostic Aids

Perform the following in order to avoid a misdiagnosis:

    • Inspect for proper operation of the brake lamps. Refer to Exterior Lighting Systems Description and Operation in Lighting Systems.
    • EMI on the vehicle speed sensor signal circuit may cause erratic cruise control operation.

For an intermittent condition, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Conditions for Enabling Cruise Control
    • The vehicle speed is greater than 40 km/h (25 mph).
    • The vehicle is not in PARK, REVERSE, NEUTRAL, or 1st gear.
    • The system voltage is within 12 volts and 16 volts.

Test description

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

  1. This step tests the CHMSL supply voltage/stop lamp supply voltage circuit for an open or for a high resistance between the stop lamp switch and the throttle actuator control (TAC) module.

    2.

  2. This step tests the cruise control set/coast switch signal circuit for an open or for a high resistance.

    3.

  3. This step tests the cruise control resume/accel switch signal circuit for an open or for a high resistance.

    4.

  4. This step tests the ignition 3 voltage circuit for an open, for a short to ground, or for a high resistance.

    5.

  5. DTCs will set in the powertrain control module (PCM) when you perform this table.

Step

Action

Yes

No

Schematic Reference : Cruise Control Schematics

Connector End View Reference: Cruise Control Connector End Views and Powertrain Control Module Connector End Views in Engine Controls - 4.8L, 5.3L, and 6.0L

1

Did you perform the Diagnostic System Check - Cruise Control?

Go to Step 2

Go to Diagnostic System Check - Cruise Control

2
  1. Install a scan tool.
  2. Turn the ignition ON, with the engine OFF.
  3. Turn the cruise control On/Off switch OFF.
  4. With the scan tool, observe the Cruise On/Off Switch parameter in the powertrain control module (PCM) Cruise Control Data data list.

Does the Cruise On/Off Switch parameter display Off?

Go to Step 4

Go to Step 3

3
  1. Turn the ignition OFF.
  2. Disconnect C4 of the multifunction switch.
  3. Turn the ignition ON, with the engine OFF.
  4. With the scan tool, observe the Cruise On/Off Switch parameter.

Does the Cruise On/Off Switch parameter display Off?

Go to Step 22

Go to Step 13

4
  1. Turn the cruise control On/Off switch ON.
  2. With the scan tool, observe the Cruise On/Off Switch parameter.

Does the Cruise On/Off Switch parameter display On?

Go to Step 5

Go to Step 11

5
  1. With the scan tool, observe the Cruise Set/Coast Switch parameter in the PCM Cruise Control Data data list.
  2. Turn the cruise control On/Off switch ON.
  3. Press and hold the cruise control Set/Coast button.

Does the Cruise Set/Coast Switch parameter Display On?

Go to Step 6

Go to Step 9

6
  1. With the scan tool, observe the Cruise Resume/Accel. Switch parameter in the PCM Cruise Control Data data list.
  2. Press and hold the Resume/Accel switch.

Does the Cruise Resume/Accel. Switch parameter Display On?

Go to Step 7

Go to Step 10

7

Do the stop lamps operate properly?

Go to Step 8

Go to Stop Lamps Inoperative in Lighting Systems

8

  1. With the scan tool, observe the Stoplamp Pedal Switch parameter in the PCM Cruise Control Data data list.
  2. Observe the scan tool parameter as the brake pedal is depress and hold the brake pedal.

Does the Stoplamp Pedal Switch parameter Display change from Released to Applied?

Go to Diagnostic Aids

Go to Step 21

9

  1. Turn the ignition OFF.
  2. Disconnect C4 of the multifunction switch.
  3. Turn the ignition ON, with the engine OFF.
  4. Connect a 3-ampere fused jumper between the cruise control set/coast switch signal circuit and the ignition 3 voltage circuit.
  5. With the scan tool, observe the Cruise Set/Coast Switch parameter.

Does the Cruise Set/Coast Switch parameter Display On?

Go to Step 22

Go to Step 19

10

  1. Turn the ignition OFF.
  2. Disconnect C4 of the multifunction switch.
  3. Turn the ignition ON, with the engine OFF.
  4. Connect a 3-ampere fused jumper between the cruise control resume/accel switch signal circuit and the ignition 3 voltage circuit.
  5. With the scan tool, observe the Cruise Resume/Accel. Switch parameter.

Does the Cruise Resume/Accel. Switch parameter Display On?

Go to Step 22

Go to Step 20

11

  1. Turn the ignition OFF.
  2. Disconnect C4 of the multifunction switch.
  3. Turn the ignition ON, with the engine OFF.
  4. Connect a test lamp between the ignition 3 voltage circuit and a good ground.

Does the test lamp illuminate?

Go to Step 12

Go to Step 15

12
  1. Connect a 3-ampere fused jumper between the ignition 3 voltage circuit and the cruise control on switch signal circuit.
  2. With the scan tool, observe the Cruise On/Off Switch parameter.

Does the Cruise On/Off Switch parameter display On?

Go to Step 22

Go to Step 18

13

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

Did you find and correct the condition?

Go to Step 29

Go to Step 14

14
  1. Turn the ignition OFF.
  2. Disconnect C1 of the throttle actuator control (TAC) module.
  3. Turn the ignition ON, with the engine OFF.
  4. With the scan tool, observe the Cruise On/Off Switch parameter.

Does the Cruise On/Off Switch parameter display On?

Go to Step 24

Go to Step 23

15

Test the cruise control set/coast switch signal circuit for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 29

Go to Step 16

16

Test the cruise control resume/accel switch signal circuit for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 29

Go to Step 17

17

Test the cruise control on switch signal circuit for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 29

Go to Step 25

18

Test the cruise control on switch signal circuit for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 29

Go to Step 23

19

Test the cruise control set/coast switch signal circuit for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 29

Go to Step 23

20

Test the cruise control resume/accel switch signal circuit for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 29

Go to Step 23

21

Test the CHMSL supply voltage/stop lamp supply voltage circuit for an open or for a high resistance between the stop lamp switch and the TAC module. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 29

Go to Step 23

22

Inspect for poor connections at the harness connector of the cruise control switch. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairsin Wiring Systems.

Did you find and correct the condition?

Go to Step 29

Go to Step 26

23

Inspect for poor connections at the harness connector of the TAC module. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 29

Go to Step 27

24

Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 29

Go to Step 28

25

Repair the open, the high resistance, or the short to ground in the Ignition 3 voltage circuit. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 29

--

26

Replace the cruise control switch. Refer to Turn Signal Multifunction Switch Replacement in Steering Wheel and Column.

Did you complete the replacement?

Go to Step 29

--

27

Replace the TAC module. Refer to Electronic Throttle Actuator Control Module Replacement in Engine Controls - 4.8L, 5.3L, and 6.0L.

Did you complete the replacement?

Go to Step 29

--

28

Important: Program the replacement PCM.

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 4.8L, 5.3L, and 6.0L.

Did you complete the replacement?

Go to Step 29

--

29

  1. Use the scan tool in order to clear the PCM DTCs.
  2. Operate the vehicle within the conditions for cruise control operation.

Does the cruise control system operate properly?

System OK

Go to Step 2