2008 Cadillac CTS headlight bulb replacement

It involves removing the entire headlamp, which involves removal of the front fascia. Chances are good that you will find a damaged connector when you get in there, there is a bulletin on it, and I have seen several. Since your vehicle should be under warranty, you may choose to take it in for service. Here is the bulletin.
#10-08-42-001: Low Beam Headlamp Bulb Diagnosis/Replacement (Inspect Bulb and Connector) - (May 14, 2010)

Subject: Low Beam Headlamp Bulb Diagnosis/Replacement (Inspect Bulb and Connector)

Models: 2008-2010 Buick Enclave

2008-2010 Cadillac CTS, CTS-V

2010 Cadillac CTS Sport Wagon, SRX

2007-2010 Cadillac Escalade, Escalade ESV, Escalade EXT

2007-2010 Chevrolet Avalanche, Silverado, Suburban, Tahoe

2008-2010 Chevrolet Malibu

2009-2010 Chevrolet Traverse

2007-2010 GMC Acadia, Sierra, Yukon, Yukon XL, Yukon Denali, Yukon Denali XL

2006-2010 Pontiac G6

2007-2010 Saturn AURA

Attention: This bulletin DOES NOT apply to vehicles equipped with High Intensity Discharge (HID) lamps.

Condition
Some customers may comment that the low beam headlamp is inoperative.

Correction
DO NOT replace the entire headlamp assembly for this condition.

Replace the bulb and inspect the connector following the procedure below.

Remove the lamp assembly, then remove the bulb. Refer to Headlamp Assembly Replacement in SI.
Inspect the connector.
"Â If the connector is NOT discolored or damaged, replace the bulb only. For bulb part numbers, see Headlamp Bulb (Low Beam) in Group 02.727 of the appropriate Parts Catalog.

"Â If the connector is discolored at the bulb interface, replace the connector (service pigtail listed below) and bulb.

Important: Use only Duraseal splice sleeves (salmon, P/N 12089189). Other splice sleeves may not protect the splice from moisture or provide a good electrical connection. Refer to Splicing Copper Wire Using Splice Sleeves in SI for splicing procedures.

1. Cut the wires of the connector approximately 45 mm (1- Â in) from the connector and splice in the service pigtail connector. Ensure that the splices are not above the connector when re-installing.

2. Replace the bulb.

Verify that the headlamp is fully functional.
Parts Information
Part Number
Description

20939657
Cable (Connector) Assembly, Headlamp (Service Pigtail)