01-08-42-001I Exterior Lamp Condensation and Replacement Guidelines - (Jan 10 2012) Driveline Control 4WD Driveline Control
|Subject:||Exterior Lamp Condensation and Replacement Guidelines|
|Models:||2013 and Prior GM Passenger Cars and Trucks|
This bulletin is being revised to update the model years to 2013. Please discard CorporateBulletin Number 01-08-42-001H (Section 08 – Body and Accessories).
The following information is being provided to better define the causes of condensationin exterior lamps and includes guidelines for determining the difference between alamp with a normal atmospheric condition (condensation) and a lamp with a water leak.
Some exterior lamps, such as cornering, turn signal, backup, headlamps or tail lampsmay exhibit very small droplets of water, a fine mist or white fog (condensation)on the inside of the lamp lens. This may be more noticeable on lamps with “multi-lens”designs and may be normal during certain weather conditions.
Condensation occurs when the air inside the lamp assembly, through atmospheric changes,reaches the “dew point”. When this takes place, the moisture in the air within thelamp assembly condenses, creating a fine mist or white fog on the inside surface ofthe lamp lens.
Most exterior lamps on General Motors vehicles use a vented design and feature a replaceablebulb assembly. They are designed to remove any accumulated moisture vapor by expellingit through a vent system. The vent system operates at all times, however, it is mosteffective when the lamps are ON or when the vehicle is in motion. Depending on thesize, shape and location of the lamp on the vehicle, and the atmospheric conditionsoccurring,the amount of time required to clear the lamp may vary from 2 to 6 hours.
Completely sealed headlamp assemblies (sealed beams) are still used on a limited numberof models being manufactured today. These lamps require the replacement of the completelamp assembly if a bulb filament burns out.Condensation2006 TrailBlazer Shown
A Fine Mist or White Fog on the Inside Surface of the Lamp Lens Occurring After aPeriod of High HumidityMay be located primarily in the lens corners (near the vents) and SHOULD NOT covermore than half the lens surface.The condition should clear of moisture when the vehicle is parked in a dry environment,or when the vehicle is driven with the lights ON.A comparison of the equivalent lamp on the opposing side of the vehicle indicatesa SIMILAR performance.
If the above conditions are noted, the customer should be advised that replacementof a lamp assembly may not correct this condition.Water LeakNew Style Pickup Shown
Numerous & Various Size Drops of Water Collecting on the Inside Surface of the LampLens After the Vehicle Has Been Exposed to Rain or a Car Washing EnvironmentA condition that covers more than half the surface of the lamp lens.An accumulation of water in the bottom of the lamp assembly.A condition that WON'T clear when the vehicle is parked in a dry environment, or whenthe vehicle is driven with the lights ON.A comparison of the equivalent lamp on the opposing side of the vehicle indicatesa different performance.
Any of the above conditions would indicate the need to service the lens or lamp assembly.
GM bulletins are intended for use by professional technicians,NOT a "do-it-yourselfer". They are written to inform thesetechnicians of conditions that may occur on some vehicles, or toprovide information that could assist in the proper service of avehicle. Properly trained technicians have the equipment,tools, safety instructions, and know-how to do a job properly andsafely. If a condition is described, DO NOT assume that thebulletin applies to your vehicle, or that your vehicle will havethat condition. See your GM dealer for information on whetheryour vehicle may benefit from the information.
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