| Diagnosis and Testing Refer to Wiring Diagrams Section 417-04, for schematic and connector information. Operation The daytime running lamps (DRL) system is designed to turn the dipped beam headlamps, parking lamps and licence plate lamps ON automatically as soon as engine is running. The instrument cluster illumination is not switched on in this mode so as to make the driver aware that he has not switched on the normal dipped beam. To increase the service life of conventional filament bulbs, the bulbs are operated at a reduced voltage of 11.5 volts maximum when the daytime running lamps (DRL) are switched on; this also reduces the brightness of the lamps. By contrast, xenon headlamps are also operated at a reduced voltage in daytime running lamp (DRL) mode, but they operate at normal brightness. Vehicles with and without daytime running lamps are no longer distinguished from each other by their different headlamp connections; instead, they have different software configurations in the GEM. The daytime running lamps (DRL) are ON under the following conditions: - Ignition switch in position RUN and
- Headlight switch in position OFF or
- Headlight switch in automatic headlamps position if light conditions are sufficient.
The daytime running lamps (DRL) are OFF under the following conditions: - The ignition switch is in any position except RUN or
- Headlight switch in parking light position or
- Headlight switch in dipped beam position or
- Headlight switch in automatic headlamps position and light conditions are not sufficient.
Inspection and Testing NOTE:Before reading out the vehicle-specific data, remake all the separated electrical connections in the vehicle, so that communication between the module and WDS is ensured. NOTE:The generic electronic module (GEM) forms part of the central junction box (CJB). NOTE:If the generic electronic module (GEM) is changed, the new one must be reinitialized. For this purpose, the vehicle-specific data is read out of the module to be replaced using WDS and is transferred to the new module. REFER to: Communications Network (418-00 Module Communications Network, Diagnosis and Testing), Generic Electronic Module (GEM) (419-10 Multifunction Electronic Modules, Diagnosis and Testing). - Verify the customer concern.
- Visually inspect for obvious signs of electrical or mechanical damage.
Visual Inspection Chart | Electrical | - Fuse(s)
- Bulb(s)
- Electrical connector(s)
- Wiring loom
- Light switch
| - Resolve any obvious causes or concerns found during the visual inspection before carrying out any further tests.
- If the cause of the concern cannot be found by visual inspection, continue with the symptom chart.
Symptom chart Symptom chart | Symptom | Possible Sources | Action | | The daytime running lamps are inoperative | * Fuse(s) * Circuit(s) * Light switch * Central Junction Box (CJB) * Generic electronic module (GEM) | * REFER to: Headlamps (417-01A Exterior Lighting, Diagnosis and Testing). | | The parking, rear and/or license lamps are inoperative with the daytime running lamps ON. | * Circuit(s) * Central Junction Box (CJB) * Generic electronic module (GEM) | * REFER to: Parking, Rear and License Plate Lamps (417-01A Exterior Lighting, Diagnosis and Testing). | |
