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

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

   • Inspect for proper operation of the following lamps:
      - The brake lamps
      - The CHMSL lamps
   • Inspect the throttle linkage for mechanical binding that may cause a system malfunction.
   • Test for a stored PCM Diagnostic Trouble Code (DTC). Refer to Powertrain On Board Diagnostic (OBD) System Check in Engine Controls-3.8L or Powertrain On Board Diagnostic (OBD) System Check in Engine Controls-5.7L.
        Refer to Engine Controls.
   • Test for a stored Traction Control System (TCS) DTC. Refer to Diagnostic System Check in Antilock Brakes.
The PCM will inhibit the cruise control when any of the following situations exist:
   • The vehicle speed is less than 25 mph.
   • The Park/Neutral Position Switch is placed into one of the following positions:
      - PARK
      - REVERSE
      - NEUTRAL
      - 1st GEAR
   • An over/under battery voltage condition exists.
   • There are low engine RPMs.
   • There are high engine RPMs (fuel cut-off).
        Refer to Engine Controls for cruise control inhibit criteria diagnosis.

Step

Action

Value(s)

Yes

No

1

Did you perform the Cruise Control System Check?

--

Go to Step 2

Go to Cruise Control System Check

2
  1. Place the cruise control switch to the OFF position.
  2. Disconnect the cruise control module.
  3. Turn the ignition switch to the RUN position.
  4. Connect a test lamp between the cruise control module connector terminal F and ground.

Does the test lamp illuminate?

--

Go to Step 3

Go to Step 10

3

Connect a test lamp between the cruise control module terminal F and terminal E.

Does the test lamp illuminate?

--

Go to Step 4

Go to Step 11

4
  1. Place the cruise switch in the ON position.
  2. Connect a test lamp between the cruise control module terminal E and terminal A.

Does the test lamp illuminate?

--

Go to Step 5

Go to Step 12

5
  1. Connect a test lamp between the cruise control module connector terminal E and terminal B.
  2. While observing the test lamp, press and hold the SET/COAST switch.

Does the test lamp illuminate?

--

Go to Step 6

Go to Step 13

6
  1. Front probe using a test light connected between the cruise control module connector between terminal E and terminal C.
  2. While observing the test lamp, press and hold the SET/COAST switch.

Does the test lamp illuminate?

--

Go to Step 14

Go to Step 7

7

Using a J 39200 DMM, measure voltage at cruise control module connector between terminal D and E.

Does the voltage measured equal the specified value?

B+

Go to Step 8

Go to Step 17

8

Connect a test light between the cruise control module connector between terminal E and terminal B.

Does the test lamp illuminate?

--

Go to Step 9

Go to Step 24

9
  1. Test circuit 84 for a short to B+.
  2. If circuit 84 is OK, replace the multi-function lever.

    3. Refer to Multifunction Lever Replacement .

Is the repair complete?

--

System OK

--

10

Repair one of the following conditions in CKT 139, between the cruise control module connector terminal F and splice S165:

    • A poor connection
    • An open

Is the repair complete?

--

System OK

--

11

Repair the open in circuit 1650, between the cruise control module terminal E connector and G109.

Is the repair complete?

--

System OK

--

12
  1. Connect a test lamp between the cruise control module connector terminal E and terminal B.
  2. While observing the test lamp, press and hold the set/coast switch.

Does the test lamp illuminate?

--

Go to Step 16

Go to Step 15

13
  1. Test circuit 84 for one of the following conditions:
    2. • A short to ground
    • A poor connection
    • An open
  2. If circuit 84 is OK, replace the multi-function lever.

    3. Refer to Multifunction Lever Replacement .

Is the repair complete?

--

System OK

--

14
  1. Test circuit 87 for a short to circuit 84.
  2. If circuit 87 is OK, replace the multi-function lever.

    3. Refer to Multifunction Lever Replacement .

Is the repair complete?

--

System OK

--

15
  1. Test for one of the following conditions in circuit 139, between the multi-function lever and splice S165:
    2. • A poor connection
    • An open
  2. If circuit 139 is OK, replace the multi-function lever.

    3. Refer to Multifunction Lever Replacement .

Is the repair complete?

--

System OK

--

16
  1. Test circuit 397 for one of the following conditions:
    2. • A short to ground
    • A poor connection
    • An open
  2. If circuit 397 is OK, replace the multi-function lever.

    3. Refer to Multifunction Lever Replacement .

Is the repair complete?

--

System OK

--

17
  1. Disconnect the cruise control release (brake) switch connector.
  2. Using a J 39200 DMM, measure the voltage between the cruise control release (brake) switch connector terminal B and ground.

Does the measured voltage equal the specified value?

B+

Go to Step 20

Go to Step 18

18
  1. Disconnect connector C250.
  2. Using a J 39200 DMM, measure the voltage between the connector C250 terminal B and ground.

Does the voltage measured equal the specified value?

B+

Go to Step 21

Go to Step 19

19
    • On vehicles equipped with NW9, repair the open in CKT 1537 between connector C250 terminal B and S 278.
    • On vehicles not equipped with NW9, repair the open in CKT 139 between connector C250 terminal B and connector C215 terminal M.

Is the repair complete?

--

System OK

--

20
  1. Test circuit 86 for one of the following conditions:
    2. • A poor connection
    • An open

    Important: Inspect the cruise control release (brake) switch for the proper alignment.

  2. If circuit 86 is OK, replace the cruise control release (brake) switch.

Is the repair complete?

--

System OK

--

21

Determine if the vehicle is automatic or manual transmission.

Does the vehicle have an automatic transmission?

--

Go to Step 22

Go to Step 23

22

Repair one of the following conditions in circuit 139, between connector C250 terminal B and the cruise control release (brake) switch connector terminal B:

    • A poor connection
    • An open

Is the repair complete?

--

System OK

--

23
  1. Test for one of the following conditions in CKT 139 between connector C250 terminal B and the cruise control (clutch) switch connector terminal B:
    2. • A poor connection
    • An open
  2. Test for one of the following conditions in CKT 379, between the cruise control (clutch) switch connector terminal A and the cruise control release (brake) switch terminal B:
    3. • A poor connection
    • An open
  3. If the connections and the circuits are OK, replace the cruise control (clutch) switch.

Is the repair complete?

--

System OK

--

24

Connect a test lamp between the cruise control module connector between terminal E and terminal C.

Does the test lamp Illuminate?

--

Go to Step 30

Go to Step 25

25
  1. Raise the drive wheels.
  2. Use the J 39200 to monitor voltage between cruise control module connector terminal K and ground.
  3. While observing the J 39200 DMM display, rotate the drive wheels by hand.

Does the voltage vary within the specified value?

0-5 volts

Go to Step 26

Go to Step 31

26
  1. Place the ignition switch in the OFF position.
  2. Test circuit 83 for one of the following conditions between the PCM and the cruise control module:
    3. • A poor connection
    • An open
  3. Reconnect the cruise control module connector.
  4. Attach a scan tool scan tool to the DLC.
  5. Start the engine.
  6. Clear any DTCs.
  7. Monitor the SMCC INHIBITED display on the scan tool .
  8. Attempt to operate the vehicle in cruise control mode.

Is SMCC Inhibited displayed or the scan tool?

--

Go to Powertrain On Board Diagnostic (OBD) System Check in Engine Controls or Powertrain On Board Diagnostic (OBD) System Check in Engine Controls

Go to Step 27

27
  1. Clear any DTCs.
  2. Select MODE 4 DIAGNOSTICS on the scan tool
  3. Use the scan tool in order to command the SMCC to allow cruise control.
  4. Use the J 39200 DMM in order to probe the cruise control module connector between terminal  H and B+.

Does the measured value equal the specified value?

B+

Go to Step 28

Go to Step 29

28

Replace the cruise control module. Refer to Cruise Control Module Replacement .

Is the repair complete?

--

System OK

--

29
  1. Test circuit 83 for a short to B+.
  2. If circuit 83 is OK, service the PCM. Refer to Powertrain On Board Diagnostic (OBD) System Check .

Is the repair complete?

--

System OK

--

30
  1. Test circuit 87 for a short to B+.
  2. If CKT 87 is OK, replace the multi-function lever.

    3. Refer to Multifunction Lever Replacement .

Is the repair complete?

--

System OK

--

31

Repair the open or the poor connection in circuit 817 between the cruise control module and splice S242.

Is the repair complete?

--

System OK

--