GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2000 🢒 LeSabre 🢒 DTC 🢒 DTC B2641 Delayed Exterior Lighting Ctrl CKT Range

Object Number: 470929 Size: MF
Dimmer Control
Temperature Sensors W/CJ2
Handling ESD Sensitive Parts Notice
Lighting Systems Components
Headlamp Switch, Ambient Light Sensor (CJ2)

Circuit Description

The twilight delay pot sensor is a potentiometer. The Instrument Panel Module determines the control setting based on the voltage from the twilight delay pot sensor. The IPM module sends out a class 2 message to the dash integration module (DIM).

Conditions for Running the DTC
    • Enable flag is set to enable.
    • The IPM is powered.

Conditions for Setting the DTC

The twilight pot voltage is less than 0.09 V or greater than 4.75 V.

Action Taken When the DTC Sets

Twilight status set to ON.

Conditions for Clearing the MIL/DTC

The IPM does not detect a voltage that is less than or greater than the predetermined value during the diagnostic self test.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Tests for the proper operation of the circuit in the high voltage range.

    2.

  2. Tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to voltage.

    3.

  3. Tests for a short to ground in the 5 volt reference circuit.

Step

Action

Value(s)

Yes

No

1

Did you perform the Lighting Systems Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the Twilight Delay Pot data parameter in the instrument panel module (IPM) data list.

Does the scan tool indicate that the Twilight Delay Pot data parameter is within the specified range?

0.09-4.8 V

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the headlamp switch.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Twilight Delay Pot data parameter.

Does the scan tool indicate that the Twilight Delay Pot data parameter is greater than the specified value?

4.8 V

Go to Step 4

Go to Step 8

4

  1. Turn OFF the ignition.
  2. Connect a 3 amp fused jumper wire between the signal circuit of the twilight delay sensor and the sensors return circuit of the twilight delay sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Twilight Delay Pot data parameter.

Does the scan tool indicate that the Twilight Delay Pot data parameter is less than the specified value?

0.09 V

Go to Step 5

Go to Step 9

5

  1. Turn OFF the ignition.
  2. Disconnect the fused jumper wire.
  3. Connect a 3 amp fused jumper wire between the 5 volt reference circuit of the twilight delay sensor and the signal circuit of the twilight delay sensor.
  4. Turn ON the ignition, with the engine OFF.
  5. With a scan tool, observe the Twilight Delay Pot data parameter.

Does the scan tool indicate that the Twilight Delay Pot data parameter is greater than the specified value?

4.8 V

Go to Step 7

Go to Step 6

6

Test the 5 volt reference circuit of the twilight delay sensor for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 12

7

Test the 5 volt reference circuit of the twilight delay sensor for a short to voltage, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 11

8

Test the signal circuit of the twilight delay sensor for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 12

9

Test the signal circuit of the twilight delay sensor for a short to voltage, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 10

10

Test the sensors return circuit of the twilight delay sensor for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 12

11

Inspect for poor connections at the harness connector of the headlamp switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 13

12

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

Did you find and correct the condition?

--

Go to Step 15

Go to Step 14

13

Replace the headlamp switch. Refer to Headlamp Switch Replacement .

Did you complete the replacement?

--

Go to Step 15

--

14

Replace the IPM. Refer to Instrument Panel Module Replacement in Body Control System.

Did you complete the replacement?

--

Go to Step 15

--

15
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK