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For 1990-2009 cars only
Makes 🢒 Buick 🢒 1998 🢒 Riviera 🢒 Body and Accessories 🢒 Lighting Systems 🢒 Twilight Sentinel Inoperative

Twilight Sentinel Inoperative Buick

Step

Action

Value(s)

Yes

No

1

Did you perform the Headlight System Check?

--

Go to Step 2

Go to Headlight System Check

2
  1. Disconnect the lamp control module (LCM) connector C1.
  2. Connect a J 39200 digital multimeter (DMM) between the LCM connector C1 cavity A7 (PNK) and ground.
  3. Turn the ignition switch to the RUN position.

Is the voltage within the specified range?

10-15 V

Go to Step 3

Go to Step 7

3
  1. Connect the DMM between the LCM connector C1 cavity A6 (PPL) and ground.
  2. Vary the twilight delay control from MIN to MAX.

Does the resistance vary within the specified range?

3.5K ohms -200K ohms

Go to Step 4

Go to Step 8

4
  1. Cover the ambient light sensor.
  2. Connect the DMM between the LCM connector C1 cavity A5 (WHT/BLK) and ground.

Is the resistance greater than the specified value?

31K ohms

Go to Step 5

Go to Step 11

5
  1. Expose the ambient light sensor to a bright incandescent light.
  2. Connect the DMM between the LCM connector C1 cavity A5 (WHT/BLK) and ground.

Is the resistance less than the specified value?

23K ohms

Go to Step 6

Go to Step 12

6

Replace the LCM.

Is the repair complete?

--

Go to Headlight System Check

--

7

Repair the open in CKT 39 (PNK) between S258 and the LCM. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Headlight System Check

--

8

Test for an open or a short to ground in CKT 1783 (PPL) between the LCM and the headlamp switch. Refer to Testing for Continuity or Testing for Short to Ground in Wiring Systems.

Is CKT 1783 OK?

--

Go to Step 9

Go to Step 14

9

Test for an open in CKT 150 (BLK) between the headlamp switch and S273. Refer to Testing for Continuity in Wiring Systems.

Is CKT 150 OK?

--

Go to Step 10

Go to Step 14

10

Replace the headlamp switch. Refer to Headlamp Switch Replacement .

Is the repair complete?

--

Go to Headlight System Check

--

11

Test for an open or a short to ground in CKT 278 (WHT/BLK or BLK) between the LCM and the ambient light sensor. Refer to Testing for Continuity or Testing for Short to Ground in Wiring Systems.

Is CKT 278 OK?

--

Go to Step 13

Go to Step 14

12

Test for an open in CKT 351 (BLK/WHT) between the ambient light sensor and S264. Refer to Testing for Continuity in Wiring Systems.

Is CKT 351 OK?

--

Go to Step 11

Go to Step 14

13

Replace the ambient light sensor. Refer to Defroster Grille Replacement in Instrument Panel, Gauges and Console.

Is the repair complete?

--

Go to Headlight System Check

--

14

Repair the suspect wiring. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Headlight System Check

--

Twilight Sentinel Inoperative Oldsmobile

Step

Action

Value(s)

Yes

No

1

Did you perform the Headlight System Check?

--

Go to Step 2

Go to Headlight System Check

2
  1. Disconnect the lamp control module (LCM) connector C2.
  2. Connect a J 39200 digital multimeter (DMM) between the LCM connector C2 cavity C (PNK) and ground.
  3. Turn the ignition switch to the RUN position.

Is the voltage within the specified range?

10-15 V

Go to Step 3

Go to Step 8

3
  1. Disconnect the LCM connector C1.
  2. Place the twilight sentinel switch in an ON position.
  3. Connect the DMM between the LCM connector C1 cavity B8 (YEL/BLK) and ground.

Is the resistance less than the specified value?

5 ohms

Go to Step 4

Go to Step 9

4
  1. Connect the DMM between the LCM connector C1 cavity A1 (PPL) and ground.
  2. Vary the twilight delay switch from MIN to MAX.

Does the resistance vary within the specified range?

3.5K ohms-200K ohms

Go to Step 5

Go to Step 10

5
  1. Cover the ambient light sensor.
  2. Connect the DMM between the LCM connector C1 cavity A2 (WHT/BLK) and ground.

Is the resistance greater than the specified value?

31K ohms

Go to Step 6

Go to Step 13

6
  1. Expose the ambient light sensor to a bright incandescent light.
  2. Connect the DMM between the LCM connector C1 cavity A2 (WHT/BLK) and ground.

Is the resistance less than the specified value?

23K ohms

Go to Step 7

Go to Step 14

7

Replace the lamp control module (LCM).

Is the repair complete?

--

Go to Headlight System Check

--

8

Repair the open in CKT 3 (PNK) between S224 and the LCM. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Headlight System Check

--

9

Test for an open in CKT 1784 (YEL/BLK) between the LCM and the panel dimming switch. Refer to Testing for Continuity in Wiring Systems.

Is CKT 1784 OK?

--

Go to Step 12

Go to Step 16

10

Test for an open or a short to ground in CKT 1783 (PPL) between the LCM and the panel dimming switch. Refer to Testing for Continuity or Testing for Short to Ground in Wiring Systems.

Is CKT 1783 OK?

--

Go to Step 11

Go to Step 16

11

Test for an open in CKT 351 (BLK/WHT) between the panel dimming switch and S246. Refer to Testing for Continuity in Wiring Systems.

Is CKT 351 OK?

--

Go to Step 12

Go to Step 16

12

Replace the panel dimming switch.

Is the repair complete?

--

Go to Headlight System Check

--

13

Test for an open or a short to ground in CKT 278 (WHT/BLK or WHT) between the LCM and the ambient light sensor. Refer to Testing for Continuity or Testing for Short to Ground in Wiring Systems.

Is CKT 278 OK?

--

Go to Step 15

Go to Step 16

14

Test for an open in CKT 351 (BLK/WHT) between the ambient light sensor and S246. Refer to Testing for Continuity in Wiring Systems.

Is CKT 351 OK?

--

Go to Step 13

Go to Step 16

15

Replace the ambient light sensor. Refer to Defroster Grille Replacement in Instrument Panel, Gauges and Console.

Is the repair complete?

--

Go to Headlight System Check

--

16

Repair the suspect wiring. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Headlight System Check

--