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Chevrolet Cobalt Tail Light Bulbs Replacement Guide
How to replace the brake / turn signal, reverse and rear side marker light bulbs in a 2005-2010 GM Chevy Cobalt.

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Cobalt Tail Light Assembly
Open Trunk Lid
Black Plastic Thumb Screw
This automotive "how-to" guide was specifically written to assist owners of the 2005, 2006, 2007, 2008, 2009 & 2010 Chevrolet Cobalt in replacing a burnt out brake / turn signal, reverse and rear side marker bulbs in the tail light assemblies.

Owners of other similar GM vehicles such as the Cruze, Impala, Malibu, Sonic, Lumina, Buick LaCrosse, Regal, Verano, Enclave, GMC Acadia, Yukon, Pontiac Grand Prix, G6, G5, Grand Am, GTO, Vibe, Sunfire, Oldsmobile Alero, Aurora, and Cutlass may also find this guide to be helpful.

Replacement tail light bulbs for the 05-10 Cobalt from Sylvania and other manufacturers with their respective part numbers are as follows: combination brake / turn signal # 3157, reverse (back up) # 921 and rear side marker # 194.

The tools needed to replace the bulbs include a 10mm open-end wrench and a 7mm socket with a ratcheting wrench.

Twist Off Thumb Screw
Pull Back Trunk Carpeting
Remove Upper 10mm Nut
The first steps are to open the trunk lid, move to the tail light with the burnt out bulb, and locate the black plastic thumb screw at the inside corner of the trunk. The fastener doubles as a hooking point for a cargo net.

Then pull back the grey trunk carpeting and remove the nut on the upper exposed screw end with the 10mm wrench.

Remove Two 7mm Screws
Pull Out Tail Light Assembly
Turn Tail Light Upside Down
Move to the outside of the trunk and remove the two 7mm screws in the grey plastic part of the tail light assembly using the socket with ratcheting wrench.

Carefully pull the tail light assembly straight away from the rear of the vehicle. If you have trouble removing it, try gently wiggling while you pull or tap on the exposed screw ends inside the trunk.

To avoid scratching the bumper, lay down a towel or rag before resting the tail light on the painted surface.


1/4 Turn Counter Clockwise
Brake / Turn Signal Bulb
Pull Out Old # 3157 Bulb
The combination brake / turn signal / parking bulb is contained in the largest black socket on the rear of the tail light assembly.

Remove it by rotating the socket 1/4 turn counter clockwise and pull it straight out of the assembly.

Pull the old # 3157 bulb straight out of the socket and push in a new one.

Insert the new bulb back into the tail light assembly and rotate the socket 1/4 turn clockwise to secure it in place.

1/4 Turn Counter Clockwise
Reverse (Back Up) Bulb
Pull Out Old # 921 Bulb
The reverse (back up) light bulb is the medium sized light grey socket located at the edge of the tail light closest to the center line of the vehicle.

Turn the socket 1/4 turn counter clockwise and pull it straight out of the tail light assembly.

Pull the old # 921 reverse bulb straight out of the socket and push in a new one.

Insert the new bulb back into the tail light and rotate it 1/4 turn clockwise to lock it in place.

If you would like to have brighter reverse lights, install some compatible replacement 921 LED bulbs.

Repeat the same steps to replace the rear side marker # 194 light bulb which is located at the other end of the tail light closest to the outer edge of the vehicle.

Line Up Tail Light Bolts
Re-Install Tail Light
Tighten Upper 10mm Nut
To replace the tail light assembly, line up the two exposed screw ends on the rear with the holes in the painted metal body and gently push them in.

Tighten the single 10mm nut on the upper screw end inside the trunk.

Replace Carpet & Fastener
Tighten Two 7mm Screws
Test New Tail Light Bulbs
Replace the grey carpeting over the corner of the trunk and twist the black plastic thumb screw on in the clockwise direction.

Then replace the two black screws on the outside of the trunk and tighten them with a 7mm socket and ratcheting wrench.

Test the new tail light bulbs by having someone step on the brake pedal, activate the hazard signals and put the transmission in reverse.

Be sure to record the bulb change in your vehicle's service records.

For more, check out my other Chevy Cobalt Repair & Maintenance Guides.

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