GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The Instrument Cluster (IPC) monitors the ambient light conditions through the ambient light sensor. The ambient light sensor is a variable resistor whose resistance changes as the ambient light level around it changes. As the ambient light decreases, the resistance of the ambient light sensor increases. The value of the ambient light sensor input will be between 0 and 5 volts (1-254 Counts).

Conditions for Running the DTC

The ignition switch is in the ON position.

Conditions for Setting the DTC

The IPC will set the DTC B2419 when it detects that the ambient light sensor input is less than 1 count or greater than 254 counts for three seconds.

Action Taken When the DTC Sets

The IPC will assume that the ambient light level indicates darkness for all functions needing the outside light status.

Conditions for Clearing the DTC

The IPC sees that the ambient light sensor input is between 1-254 Counts.

Test Description

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

  1. Perform the Lighting Systems Diagnostic System Check before continuing with the diagnosis of this DTC.

  2. Checks if the value that the Instrument Cluster (IPC) is reading from the ambient light sensor is within the valid range.

  3. Checks if the value that the Instrument Cluster (IPC) is reading from the ambient light sensor is too High.

  4. Checks if the value that the Instrument Cluster (IPC) is reading from the ambient light sensor is too low.

Step

Action

Value(s)

Yes

No

Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics

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 Photo data parameter in the Instrument Panel Cluster (IPC) data list.

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

1 - 254 Counts

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 ambient light sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Twilight Photo data parameter.

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

254 Counts

Go to Step 4

Go to Step 5

4

  1. Turn OFF the ignition.
  2. Connect a 3 amp fused jumper wire between the signal circuit of the ambient light sensor and the low reference circuit of the ambient light sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Twilight Photo data parameter.

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

1 Count

Go to Step 8

Go to Step 6

5

Test the signal circuit of the ambient light 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 12

Go to Step 9

6

Test the signal circuit of the ambient light 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 12

Go to Step 7

7

Test the low reference circuit of the ambient light 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 12

Go to Step 9

8

Inspect for poor connections at the harness connector of the ambient light sensor. 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 12

Go to Step 10

9

Inspect for poor connections at the harness connector of the Instrument Cluster (IPC). 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 12

Go to Step 11

10

Replace the ambient light sensor. Refer to Sunload and Twilight Sentinel Sensor Replacement in Instrument Panel, Gages and Console.

Did you complete the replacement?

--

Go to Step 12

--

11

Replace the Instrument Cluster (IPC). Refer to Instrument Cluster Replacement in Instrument Panel, Gages and Console.

Did you complete the replacement?

--

Go to Step 12

--

12

  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