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HOMESERVICE MANUALSCHEVROLET2006COBALT SS, 4D SEDAN, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 7 (LIGHTING SYSTEMS)DIAGNOSTIC INFORMATION AND PROCEDURESDTC B2623TEST DESCRIPTION
2006 Chevrolet Cobalt SS, 4D Sedan, Standard

Test Description

2006 Chevrolet Cobalt SS, 4D Sedan, StandardSECTION Test Description
WARNING: This page is about a different car, the 2005 Saturn L300. However, it is still accessible from the selected car via links, so may be relevant.

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

  1. 2:  The normal operating voltage of the instrument panel dimmer switch is 0.4-4.5 volts.
  2. 3:  This step determines if there is a problem with the dimmer switch.
DTC B2623

Step Action Value(s) Yes No
Schematic Reference: Interior Lights Dimming Schematics 
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2 
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the I/P Dimmer Input data parameter in the Interior Lamps data list.
Does the scan tool indicate that the I/P Dimmer Input parameter is greater than the specified range?		 4.5 V Go to Step 3  Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems
3 
  1. Turn OFF the ignition.
  2. Disconnect the instrument panel dimmer switch.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the I/P Dimmer Input data parameter.
Does the scan tool indicate that the I/P Dimmer Input data parameter is greater than the specified value?		 4.5 V Go to Step 4  Go to Step 5 
4 Test the 5-volt reference circuit and the instrument panel lamps dimmer switch signal circuit for an open or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 9  Go to Step 6 
5 Inspect for poor connections at the harness connector of the instrument panel dimmer 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 9  Go to Step 7 
6 Inspect for poor connections at the harness connector of the body control module (BCM). 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 9  Go to Step 8 
7 Replace the instrument panel dimmer switch.
Did you complete the replacement?		 - Go to Step 9  Go to Step 9 
8 Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup and programming.
Did you complete the replacement?		 - Go to Step 9  -
9
  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
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.