GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 1998 🢒 Skylark 🢒 Body and Accessories 🢒 Cruise Control 🢒 Cruise Control Inoperative

Important: Perform the following steps in order to avoid misdiagnosis:

   • Inspect for proper operation of the brake lamps and the high mounted stop lamp (HMSL).
   • Inspect the throttle linkage for mechanical binding that may cause a system malfunction.
   • Test for a stored PCM Diagnostic Trouble Codes (DTCs). Refer to Diagnostic Trouble Code (DTC) List in Engine Controls-3.1L or Diagnostic Trouble Code (DTC) List in Engine Controls-2.4L.
The PCM will inhibit the cruise control when any of the following situations exist:
   • The engine is OFF
   • An automatic transaxle is in PARK or NEUTRAL position.
   • A manual transaxle is out of gear or in NEUTRAL.
   • During high vehicle speed fuel cut-off.
   • During high engine RPMs fuel cut-off.
   • A four speed automatic transaxle equipped car is in REVERSE.

Step

Action

Value(s)

Yes

No

1
  1. Move the cruise control switch to the OFF position.
  2. Disconnect the cruise control module.
  3. Turn the ignition switch to the RUN position.
  4. Using a test lamp, front probe the cruise control module connector between terminal F and ground

Is the test lamp ON?

--

Go to Step 2

Go to Step 3

2

Using a test lamp, front probe the cruise control module connector between terminal  F and terminal E.

Is the test lamp ON?

--

Go to Step 4

Go to Step 5

3

Repair the poor connection or open in CKT 339.

Is the repair complete?

--

System OK

--

4

Move the cruise switch to ON position.

Using a test lamp, front probe the cruise control module connector between terminal E and terminal A.

Is the test lamp ON?

--

Go to Step 6

Go to Step 12

5

Repair the poor connection or open in CKT 451. Is the repair complete?

--

System OK

--

6
  1. Using a test lamp, front probe the cruise control module connector between terminal E and terminal B.
  2. Press and hold the set/coast switch while observing the test lamp.

Does the test lamp illuminate?

--

Go to Step 7

Go to Step 8

7
  1. Using a test lamp, front probe the cruise control module connector between terminal E and terminal C.
  2. Press and hold the R/A switch while observing the test lamp.

Does the test lamp illuminate?

--

Go to Step 9

Go to Step 10

8
  1. Inspect for a short to ground on CKT 84.
  2. Inspect CKT 84 for a poor connection or an open.
  3. If CKT 84 is OK, replace the multi-function lever. Refer to Multifunction, Turn Signal, and Hazard Switch Replacement - On Vehicle in Steering Wheel and Column.

Is the repair complete?

--

System OK

--

9

Using a test lamp, front probe the cruise control module connector between terminal E and terminal D.

Is the test lamp ON?

--

Go to Step 11

Go to Step 12

10
  1. Inspect for a short to ground on CKT 87.
  2. Inspect CKT 87 for a poor connection or an open.
  3. If CKT 87 is OK, replace the multi-function lever. Refer to Multifunction, Turn Signal, and Hazard Switch Replacement - On Vehicle in Steering Wheel and Column.

Is the repair complete?

--

System OK

--

11
  1. Set the park brake.
  2. Raise the drive wheels.
  3. Measure the voltage with J 39200 (DMM) at the cruise control module connector between terminal K and ground.
  4. Rotate the drive wheels by hand, while observing the display of the J 39200 .

Does the voltage vary?

--

Go to Step 19

Go to Step 20

12

Using a test lamp, back probe the cruise control brake switch connector between terminal B and ground.

Is the test lamp ON?

--

Go to Step 26

Go to Step 13

13
  1. Inspect CKT 39 for a poor connection or an open.
  2. Inspect the cruise control brake switch for proper adjustment.
  3. If the adjustment is OK, replace the cruise control brake switch. Refer to Brake Release Switch Replacement in Instrument Panel, Gauges and Console.

Is the repair complete?

--

System OK

--

14
  1. Using a test lamp, front probe the cruise control module connector between terminal E and terminal B.
  2. Press and hold the set/coast switch while observing the test lamp.

Does the test lamp illuminate?

--

Go to Step 16

Go to Step 15

15
  1. Using a test lamp, front probe the cruise control module connector between terminal C and terminal E.
  2. Press and hold the R/A switch while observing the test lamp.

Does the test lamp illuminate?

--

Go to Step 18

Go to Step 17

16
  1. Inspect CKT 397 for a short to ground.
  2. Inspect CKT 397 for a poor connection or an open between the cruise control module connector and the multi-function lever.
  3. If the connection is OK, replace the multi-function lever. Refer to Multifunction, Turn Signal, and Hazard Switch Replacement - On Vehicle in Steering Wheel and Column.

Is the repair complete?

--

System OK

--

17
  1. Inspect for a poor connection or an open in the multi-function lever harness.
  2. Inspect CKT 339 for a poor connection or an open.
  3. If CKT 339 is OK, replace the multi-function lever. Refer to Multifunction, Turn Signal, and Hazard Switch Replacement - On Vehicle in Steering Wheel and Column.

Is the repair complete?

--

System OK

--

18
  1. Inspect CKT 84 for a short to CKT 87 or to ground.
  2. Inspect for a poor connection at the multi-function lever.
  3. If CKT 339 is OK, replace the multi-function lever. Refer to Multifunction, Turn Signal, and Hazard Switch Replacement - On Vehicle in Steering Wheel and Column.

Is the repair complete?

--

System OK

--

19
  1. Turn the ignition switch OFF.
  2. Inspect CKT 83 for a poor connection or an open between the PCM and the cruise control module.
  3. Reinstall the cruise control module.
  4. Install Scan Tool to the DLC.
  5. Start the engine.
  6. Clear any DTCs.
  7. Monitor the CRUISE INHIBITED display on the scan tool.
  8. Make an attempt to operate the vehicle in cruise control mode.

Is CRUISE INHIBITED shown on the Scan Tool ?

--

Go to Step 22

Go to Step 21

20

Inspect CKT 817 for a poor connection or an open between the cruise control module connector. Refer to Engine Controls.

Is the repair complete?

--

System OK

--

21
  1. Clear any DTCs.
  2. Command the PCM to allow cruise.
  3. Using J 39200 , probe the cruise control module connector between terminal H and the battery voltage.

Is the approximate battery voltage measured?

--

Go to Step 23

Go to Step 24

22

Refer to Engine Controls for diagnosis.

Is the diagnosis complete?

--

System OK

--

23

Replace the cruise control module. Refer to Engine Controls.

Is the repair complete?

--

System OK

--

24

Inspect CKT 83 for a short to B+.

If the circuit is OK, service the PCM. Refer to Engine Controls.

Is the repair complete?

--

System OK

--

25

This procedure varies between a manual transaxle and an automatic transaxle.

Is this vehicle equipped with a manual transaxle?

--

Go to Step 27

Go to Step 26

26

(Automatic Transaxle) Repair the poor connection or open in CKT  420.

Is the repair complete?

--

System OK

--

27

(Manual Transaxle) Backprobe with a test light the cruise control clutch switch connector between terminal B and ground.

Is the test light ON?

--

Go to Step 28

Go to Step 29

28

Repair the poor connection or open in CKT 379.

Is the repair complete?

--

System OK

--

29
  1. Inspect CKT 86 for a poor connection or an open.
  2. If CKT 86 is OK, replace the cruise control clutch switch. Refer to Brake Release Switch Replacement .

Is the repair complete?

--

System OK

--