GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2006 🢒 Lucerne 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 Cruise Control Inoperative/Malfunctioning

Diagnostic Aids

In order to avoid misdiagnosis, inspect for the following:

    • Ensure that the following cruise control switches are not stuck in the engaged position:
       - On/Off switch
       - Set/Coast switch
       - Resume/Accel switch
    • Proper operation of the brake lamps -- Refer to Exterior Lighting Systems Description and Operation.

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

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 9-16 volts.
    • The park brake is not applied.

Test Description

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

  1. This step tests the ignition 1 voltage circuit for an open, for a short to ground, or for a high resistance.

Step

Action

Values

Yes

No

Schematic Reference: Cruise Control Schematics

Connector End View Reference: Master Electrical Component List

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With the scan tool, observe the Cruise Control Switch parameter in the Body and Accessories body control module (BCM) Data list.

Does the Cruise Control Switch parameter display Off?

--

Go to Step 3

Go to Step 7

3
  1. Turn the cruise control On/Off switch ON.
  2. With the scan tool, observe the Cruise Control Switch parameter.

Does the Cruise Control Switch parameter display On?

--

Go to Step 4

Go to Step 6

4
  1. Turn the cruise control on/off switch ON.
  2. With the scan tool, observe the Cruise Control Switch parameter.
  3. Press and hold the cruise control set/coast button.

Does the Cruise Control Switch parameter display Set?

--

Go to Step 5

Go to Step 8

5
  1. With the scan tool, observe the Cruise Control Switch parameter.
  2. Press and hold the resume/accel switch.

Does the Cruise Control Switch parameter Display Resume?

--

Go to Diagnostic Aids

Go to Step 8

6

  1. Turn OFF the ignition.
  2. Disconnect C1.
  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 8

Go to Step 13

7

Important: The cruise control on/off switch must be turned ON in order to correctly view the set/coast switch resistance values with the DMM.

  1. Turn OFF the ignition.
  2. Disconnect C1.
  3. With a DMM, measure the resistance of the cruise control switch between the ignition 1 voltage circuit and the cruise control set/coast and resume/accelerate switch signal circuit.
  4. Individually activate and hold the cruise control function switches while measuring the resistance value of each cruise control function switch.

Do the cruise control function switch resistance values measure between the specified values?

Off = O.L.

On = 7.8 K-8.6 K

Resume = 2.7 K-3.0 K

Set = 1.2 K-1.3 K

Go to Step 10

Go to Step 11

8

Important: The cruise control on/off switch must be turned ON in order to correctly view the set/coast switch resistance values with the DMM.

  1. Turn OFF the ignition.
  2. Disconnect C1.
  3. With a DMM, measure the resistance of the cruise control switch between the ignition 1 voltage circuit and the cruise control set/coast and resume/accelerate switch signal circuit.
  4. Individually activate and hold the cruise control function switches while measuring the resistance value of each cruise control function switch.

Do the cruise control function switch resistance values measure between the specified values?

Off = O.L.

On = 7.8 K-8.6 K

Resume = 2.7 K-3.0 K

Set = 1.2 K-1.3 K

Go to Step 9

Go to Step 11

9

Test the cruise control set/coast and resume/accel switch signal circuit for the following:

    • High resistance
    • Open
    • Short to ground
    • Short to voltage

Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 12

10

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

Did you find and correct the condition?

--

Go to Step 16

Go to Step 12

11

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.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 14

12

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

Did you find and correct the condition?

--

Go to Step 16

Go to Step 15

13

Repair the following in the ignition 1 voltage circuit:

    • An open
    • A high resistance
    • A short to ground

Refer to Circuit Testing and Wiring Repairs.

Did you complete the repair?

--

Go to Step 16

--

14

Replace the cruise control switch. Refer to Turn Signal Multifunction Switch Replacement.

Did you complete the replacement?

--

Go to Step 16

--

15

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

Did you complete the replacement?

--

Go to Step 16

--

16

Operate the vehicle within the conditions for cruise control operation.

Does the cruise control system operate properly?

--

System OK

Go to Step 2