GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

DEFINITION: This table diagnoses the cruise control function is totally inoperative. It does not diagnose the lamp(s) only are inoperative or that the overdrive cutoff is inoperative.

1

Did you review the Cruise Control System Description operation and perform the necessary inspections?

--

Go to Step 2

Go to Symptoms - Cruise Control

2

Verify that the cruise control is inoperative.

Does the cruise control system operate normally?

--

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

  1. Perform the Powertrain On Board Diagnostic (OBD) System Check.
  2. Observe the DTC display using the scan tool.

Is DTC P0500 stored in memory?

--

Go to Step 4

Go to Step 5

4

Refer to DTC P0500 Vehicle Speed Sensor (VSS) Circuit in Engine Controls.

Did you find and correct the condition?

--

Go to Step 27

--

5

  1. Disconnect the cruise control servo connector.
  2. Remove the cap from cruise control servo.
  3. Disconnect the cruise control cable from the cruise control servo. Refer to Cruise Control Cable Replacement for access.
  4. Rotate the cruise control servo lever counterclockwise and release.

Did the servo lever turn approximately 1/3 revolution counterclockwise and return to it's normal position when released?

--

Go to Step 6

Go to Step 26

6

With the cruise control servo lever in it's normal position, attempt to rotate the lever in a clockwise direction.

Did the lever rotate in a clockwise direction?

--

Go to Step 26

Go to Step 7

7

  1. Reconnect the cruise control cable to the cruise control servo.
  2. Inspect the amount of play in the cruise control cable. Refer to Cruise Control Cable Replacement .

Is the amount of play in the cruise control servo cable within tolerance?

--

Go to Step 8

Go to Step 25

8

With the cruise control servo connector still disconnected:

  1. Turn ON the ignition, with the engine OFF.
  2. Connect a test lamp between cavity 12 of the cruise control servo connector and a good ground.

Did the test lamp illuminate?

--

Go to Step 9

Go to Step 17

9

With the cruise control servo connector still disconnected and the ignition ON:

  1. Connect the test lamp between cavity 6 of the cruise control servo connector and a good ground.
  2. Depress and release the brake pedal.

Does the test lamp turn OFF when the brake pedal is depressed and turn ON when the brake pedal is released?

--

Go to Step 10

Go to Step 18

10

With the cruise control servo connector still disconnected:

  1. Connect the test lamp between cavity 2 of the cruise control servo connector and a good ground.
  2. Depress and release the brake pedal.

Does the test lamp turn ON when the brake pedal is depressed and OFF when the brake pedal is released?

--

Go to Step 11

Go to Step 18

11

With the cruise control servo connector still disconnected and the ignition ON:

Connect the test lamp between cavity 11 and cavity 12 of the cruise control servo connector.

Does the test lamp illuminate?

--

Go to Step 12

Go to Step 21

12

With the cruise control servo connector still disconnected and the ignition ON:

  1. Depress and hold the main cruise control switch.
  2. Measure the voltage between cavity 8 of the cruise control servo connector and a good ground.

Does the voltage measure near the specified value?

12 Volts

Go to Step 13

Go to Step 22

13

With the cruise control servo connector still disconnected, measure the resistance between cavity 5 and cavity 8 of the cruise control servo connector with the cruise control mode switch in the following positions:

    • CANCEL
    • RES/ACC
    • SET/COAST

Does the resistance measure near the specified values?

    • CANCEL 0 - .5 Ohms
    • RES/ACC 900 - 920 Ohms
    • SET/COAST  220 - 240 Ohms

Go to Step 14

Go to Step 23

14

Does the vehicle have an automatic transaxle?

--

Go to Step 15

Go to Step 16

15

  1. Move the transmission range switch to any position except P or N .
  2. Test for an open condition between cavity 9 of the cruise control servo and ground.

Did you measure an open condition?

--

Go to Step 26

Go to Step 24

16

  1. Test for an open condition between cavity 9 of the cruise control servo and ground.
  2. Make sure the clutch pedal is not depressed.

Did you measure an open condition?

--

Go to Step 26

Go to Step 24

17

Repair the open condition in the BLU/BLK wire between cavity 12 of the cruise control servo connector and cavity 2 of the main relay. Refer to Wiring Repairs in wiring systems.

Did you complete the repair?

--

Go to Step 27

--

18

Inspect the stoplamp switch adjustment. Refer to Stop Lamp Switch Adjustment in Hydraulic Brakes.

Is the stoplamp switch in adjustment?

--

Go to Step 20

Go to Step 19

19

Adjust the stoplamp switch. Refer to Stop Lamp Switch Adjustment in Hydraulic Brakes.

Did you complete the adjustment?

--

Go to Step 27

--

20

Repair the open or short to voltage condition in the stoplamp switch circuit between the cruise control servo and battery positive voltage. Refer to Wiring Repairs in Wiring Systems or Stop Lamp Switch Replacement in Hydraulic Brakes.

Did you complete the repair or replacement?

--

Go to Step 27

--

21

Repair the open in the BLK wire of the ground circuit between cavity 11 of the cruise control servo connector and ground. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 27

--

22

Repair the open in the battery positive voltage circuit between cavity 8 of the cruise control servo connector and battery positive voltage. Refer to Wiring Repairs in Wiring Systems or Cruise Control Switch Replacement .

Did you complete the repair?

--

Go to Step 27

--

23

Repair the open or short to ground condition in the cruise control mode switch control circuit between cavity 5 and cavity 8 of the cruise control servo connector. Refer to Wiring Repairs in Wiring Systems or Cruise Control Engagement Switch Replacement .

Did you complete the repair?

--

Go to Step 27

--

24

Repair the short to ground condition between cavity 9 of the cruise control servo connector and ground.

Refer to Wiring Repairs in Wiring Systems, Transmission Range Switch Replacement in Automatic Transmission - 4 Speed-M41, or Cruise Release Switch Replacement.

Did you complete the repair?

--

Go to Step 27

--

25

Adjust the amount of play in the cruise control servo cable. Refer to Cruise Control Cable Replacement for the specified adjustment.

Did you adjust the cruise control cable within adjustment?

--

Go to Step 27

--

26

Replace the cruise control servo. Refer to Cruise Control Servo Replacement .

Did you complete the replacement?

--

Go to Step 27

--

27

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 3