GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2006 🢒 Grand Prix 🢒 Accessories 🢒 Cruise Control 🢒 Cruise Control Inoperative/Malfunctioning

Diagnostic Aids

Caution: Refer to SIR Caution in the Preface section.

Disable the inflatable restraint steering wheel module when performing this diagnostic table. Refer to SIR Disabling and Enabling .

Perform the following in order to avoid misdiagnosis:

    • Ensure that the following cruise control switches are not stuck in the engaged position:
       - On/Off switch
       - Set/Coast switch
       - Resume/Accel switch
    • Inspect for proper operation of the stop lamps. Refer to Exterior Lighting Systems Description and Operation .
    • EMI on the speed sensor signal circuit may cause erratic cruise control operation.
    • For an intermittent condition, refer to Testing for Intermittent Conditions and Poor Connections .

Test Description

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

  1. DTCs will set in the PCM when you perform this diagnostic table.

Step

Action

Values

Yes

No

Schematic Reference: Cruise Control Schematics

Connector End View Reference: Powertrain Control Module Connector End Views for the 3.8L engine

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Is DTC P0573 current in the powertrain control module (PCM)?

--

Go to DTC P0573

Go to Step 3

3
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Turn the cruise control On/Off switch OFF.
  4. With the scan tool, observe the following cruise control parameters in the Cruise Control data list:
    5. • Cruise On/Off Switch
    • Cruise Resume/Accel Switch
    • Cruise Set/Coast Switch

Do any of the parameters listed above display On?

--

Go to Step 10

Go to Step 4

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

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.
  2. Press and hold the set/coast switch.

Does the Cruise Set/Coast Switch parameter display On?

--

Go to Step 6

Go to Step 17

6
  1. With the scan tool, observe the Cruise Resume/Accel Switch parameter.
  2. Press and hold the resume/accel switch.

Does the Cruise Resume/Accel Switch parameter display On?

--

Go to Step 7

Go to Step 17

7
  1. Turn OFF the ignition.
  2. Connect C3 at the body control module (BCM).
  3. Disconnect the throttle actuator control (TAC) module.
  4. Turn ON the ignition, with the engine OFF.
  5. With a DMM, measure the voltage of the vehicle speed signal circuit.

Does the voltage measure greater than the specified value?

8.5 V

Go to Step 8

Go to Step 14

8

Test the vehicle speed signal circuit for a short to voltage. Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 25

Go to Step 9

9

With a DMM, measure the voltage of the stop lamp switch signal circuit.

Does the voltage measure greater than the specified value?

8.5 V

Go to Step 19

Go to Step 20

10
  1. Turn OFF the ignition.
  2. Disconnect the cruise switch.
  3. Turn ON the ignition, with the engine OFF.
  4. With the scan tool, observe the following cruise control parameters:
    5. • Cruise On/Off Switch
    • Cruise Resume/Accel Switch
    • Cruise Set/Coast Switch

Do any of the parameters listed above display On?

--

Go to Step 15

Go to Step 17

11
  1. Turn OFF the ignition.
  2. Disconnect the cruise switch.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the ignition 1 voltage circuit and a good ground.

Does the test lamp illuminate?

--

Go to Step 12

Go to Step 21

12

Test the ignition 1 voltage circuit for an open or for a high resistance between C201 and the cruise control switch. Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 25

Go to Step 13

13
  1. Turn OFF the ignition.
  2. Connect a 3-amp fused jumper between the ignition 1 voltage circuit and the cruise control set/coast and resume/accelerate switch signal circuit.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Cruise Mode Signal parameter in the PCM Cruise Control data list.

Does the Cruise Mode Signal parameter display at or greater than the specified voltage?

4.5 V

Go to Step 17

Go to Step 16

14

Test the vehicle speed signal circuit for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 25

Go to Step 18

15

Test the cruise control set/coast and resume/accel switch signal circuit for a short to voltage. Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 25

Go to Step 18

16

Test the cruise control set/coast and resume/accel switch signal circuit for an open, for a short to ground, or for a high resistance. Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 25

Go to Step 18

17

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 Repairs .

Did you find and correct the condition?

--

Go to Step 25

Go to Step 22

18

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

Did you find and correct the condition?

--

Go to Step 25

Go to Step 24

19

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 .

Did you find and correct the condition?

--

Go to Step 25

Go to Step 23

20

Repair the open or the high resistance in the stop lamp switch signal circuit between the underhood fuse block and the TAC module. Refer to Wiring Repairs .

Did you complete the repair?

--

Go to Step 25

--

21

Repair the open, the short to ground, or the high resistance in the ignition 1 voltage circuit. Refer to Wiring Repairs .

Did you complete the repair?

--

Go to Step 25

--

22

Replace the multifunction turn signal switch. Refer to Turn Signal Multifunction Switch Replacement .

Did you complete the replacement?

--

Go to Step 25

--

23

Replace the TAC module. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 25

--

24

Replace the PCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 25

--

25

  1. Enable the inflatable restraint steering wheel module. Refer to SIR Disabling and Enabling .
  2. Use the scan tool in order to clear the PCM DTCs.
  3. Operate the cruise control system in order to verify the repair.

Does the cruise control system operate properly?

--

System OK

Go to Step 2