Lighting - Headlamps/Front Fog Lamps Leaking Or Fogged

2010 Mercedes Benz Truck GL 350 BLUETEC (164.825) V6-3.0L DSL Turbo (642.820)
Vehicle: All Technical Service Bulletins
Lighting - Headlamps/Front Fog Lamps Leaking Or Fogged
Headlamps/front fog lamps leaking or fogged
Topic number LI82.10-P-050139
Version 1
Design group 82.10 Exterior lights
Date 08-18-2010
Validity All vehicles
Reason for change Remedy revised and the new model series incorporated / Supersedes DTB T-B-82.10/334
Complaint:
Headlamps/front fog lamps leaking or fogged
Cause:
As the headlamp is cooling down, e.g. after switching off, in rain or when washed, air is drawn in and the moisture from the air condenses on the
headlamp lens.
The ventilation of the headlamps ensures that this condensation is dissipated again after a short period of operation.
If the customer complains about fogging that is not present at the time of the workshop visit, then this is condensation. For these reasons,
condensation is a natural phenomenon and does not indicate a defect or malfunction; warranty and goodwill claims with this complaint will be
rejected.
Remedy:
Remedy 1:
A defective headlamp can be identified as follows:
1. Check headlamps for external damage and also check for correct seating/locking of the caps.
2. If the headlamp exhibits external damage:
3. Remove/install/replace headlamp.
4. Check headlamp setting and correct if necessary.
Note:
If there is external damage on the headlamp or if the caps are not correctly seated/locked, there is no grounds for a warranty or goodwill
case.
Remedy 2:
Clearing fogged/condensed headlamps:
1. Drive the vehicle into the workshop and connect the exhaust extractor.
Note:
In dry weather (temperature higher than +15°C/+59°F), you can also treat the vehicle out of doors.
Do not perform an engine wash before the defogging test.
2. Start the engine and switch on the following lights:
a. Main headlamps and front fog lamps fogged: High and low beams, front fog lamps, hazard warning system.
b. Only front fog lamps fogged: Front fog lamps.
3. Leave the vehicle in this state for 40 minutes.
4. Switch off all lights and the engine.
2010 Mercedes Benz Truck GL 350 BLUETEC (164.825) V6-3.0L DSL Turbo (642.820)
5. Check the fogging; a noticeable reduction in the amount of fogging must be visible (progress of defogging process).
Note:
If no reduction in the degree of fogging is visible, the headlamp is defective and must be replaced.
It is not physically possible to defog the headlamps completely.
Fogging does not impair the operation or the service life of the headlamp.
Symptoms