Interior Backlighting Does Not Dim. Buick LaCrosse 2005

For 1990-2009 cars only

Makes 🢒 Buick 🢒 2005 🢒 LaCrosse 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 Interior Backlighting Does Not Dim

Step	Action	Yes	No
Schematic Reference: Interior Lights Dimming Schematics Connector End View Reference: Master Electrical Component List
1	Did you perform the Diagnostic System Check - Vehicle?	Go to Step 2	Go to Diagnostic System Check - Vehicle
2	Verify that the interior backlighting does not dim. Does the interior backlighting operate normally?	Go to Testing for Intermittent Conditions and Poor Connections	Go to Step 3
3	Do the instrument panel (I/P) lamps dim?	Go to Step 13	Go to Step 4
4	Do the class 2 lamps dim?	Go to Step 5	Go to Step 6
5	Test for a short to battery positive voltage in the I/P lamps supply voltage circuit. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	Go to Step 14	Go to Step 13
6	Disconnect the lamp switch assembly. Does all the illumination of the backlight components turn OFF?	Go to Step 8	Go to Step 7
7	Test for a short to battery positive voltage on the I/P dimming control circuit. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	Go to Step 14	Go to Step 8
8	Test for a poor connection, an open, or a short to ground in the I/P dimming control circuit. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	Go to Step 14	Go to Step 9
9	Test for a poor connection or an open in the I/P dimming return circuit. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	Go to Step 14	Go to Step 10
10	Reconnect the lamp switch assembly. Disconnect the body control module (BCM) connector C1. Using a DMM, measure the resistance between the I/P dimming voltage reference circuit and the I/P dimming control circuit. Vary the I/P dimming switch from full bright to full dim. Does the DMM, display change?	Go to Step 13	Go to Step 11
11	Test for an open or a short to battery positive voltage in the I/P dimming voltage reference circuit. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	Go to Step 14	Go to Step 12
12	Replace the lamp switch assembly. Refer to Headlamp Switch Replacement . Did you complete the replacement?	Go to Step 14	--
13	Replace the BCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement?	Go to Step 14	--
14	Operate the system in order to verify the repair. Did you correct the condition?	System OK	Go to Step 2