EXTERIOR LIGHTS CRACKING DUE TO HARSH CHEMICAL CLEANERS

Subject: EXTERIOR LAMPS CRACKING DUE TO EXPOSURE TO HARSH CHEMICAL CLEANERS

Cadillac exterior lamps may develop stress cracks when exposed to certain chemicals. Stress cracks will affect the outer lens of a lamp where the lens is welded to the lamp housing. The cracks can vary from a fraction of an inch to several inches in length and typically there are several cracks along the lens to housing weld. Other chemicals may produce a granular effect on the surface of the lens but will not result in an actual crack.

Stress cracks are formed when a chemical reacts with the outer lens and attempts to deform the lens. Because the lens is firmly affixed to the lamp housing the lens cannot deform and cracks to relieve the stress.

Chemicals that produce stress cracks may be found in certain glass cleaners and cleaning solvents used to prepare a vehicle for painting or for customer purchase.

Listed below are the chemicals that may produce stress cracks and some of the cleaning products that contain the chemicals.

Partial Listing Of Chemical Class Names Commercial Products -------------------- ------------------- ETHERS butyl cellosolve Sparkle Glass Cleaner 2-butoxy-ethanol Vivid Glass Cleaner ethylene glycol monobutyl ether Rinse Away Beauty Glo Spray Wax BB Glass Cleaner GM Glass Cleaner KETONES MEK Lacquers MIBK Spray Paints methyl ethyl ketone Gumout Products methyl isobutyl ketone Oatey Cleaner 2-butanone Paint Thinners acetone Liquid Adhesives

ALCOHOLS (monohydric) methanol Windshield Washer Solvents methyl alcohol M-Lens Cleaner isopropyl alcohol Glass Prep #1 propanol Paints and Thinners Paint Removers AROMATIC HYDROCARBONS xylene Acrylic Cleaning Thinner 1631 toluene Paints and Lacquers methyl benzene Purge Thinner dimethyl benzene Gumout Products xylol toluol phenylmethane

CHLORINATED HYDROCARBONS methylene chloride Paint Removers 1,1,1-trichloroethane Spray Paints dichloremethane Metal Primer 9981748 methyl chloroform 9981228 Fabric Cleaner

PHENOLS nonylphenol Surfionic N-40

ESTERS ethyl acetate Industrial Solvents butyl acetate Lacquers

To eliminate the chance of cracking an exterior lens do not use any of the above chemicals on or near an exterior lamp.

IMPORTANT:If a chemical or cleaner is used on a vehicle, all lamp assemblies near the area to be cleaned should be removed and not reinstalled until all chemicals are completely cleansed from the area.

The best cleaning agent for all exterior lamps is a mild soap and water solution.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.