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Daytime Running Lights are a function of the Body Control Module so there is no fuse listed, although there are a number of BCM fuses in the fuse Box Diagrams that you can check.
However, if one light is normal and the other is dim (but still lit), the problem will not be a fuse as you have power to them. Fuses either work or they don't. The problem will be the bulb, the HID module or the grounds to it. The condensation is a clue has likely caused corrosion somewhere.
An auto electrician has probably come across this before and would be able to do the BCM module and HID module testing with a professional scan tool computer. You really don't want to mess with the voltages in them, or replace parts that aren't needed as they are extremely expensive.
Doesn't use a DRL module . Has DRL relay .
Symptom Chart
Condition
Possible Sources
Action
The daytime running lamps are inoperative.
Fuse
Circuit(s)
Daytime running lamps (DRL) relay
Light switch
Go To Pinpoint Test A .
Free wiring diagrams here http://www.bbbind.com/free-tsb/ Enter vehicle info. Year , make , model an engine . Under system click on lighting , then under subsystem click on daytime running lamps . Click the search button then the blue links . Looking at the wiring diagram i see the DRL relay is located in the BJB - this is the fuse / relay box in the engine compartment . To see location under system click on electrical distribution ,then on junction block . picture of fuse box shows location .
That piece you think is a ceramic DRL module is a resistor , When in DRL mode voltage to the low beam headlamps circuit goes through that resistor dimming the headlamps from low beam to daytime running lamps . It sounds to me like you need a new resistor ,but without doing some electrical testing it could be a lot of things . The DRL relay in the under hood fuse box could have a problem , could be the BCM - body control module , the ambient light sensor etc... Here is how daytime running lamps work .
Daytime Running Lamps (DRL)
The ambient light sensor is a light sensitive transistor that varies its voltage signal to the body control module (BCM) in response to changes to the outside (ambient) light level. When the BCM receives this signal it will either turn on the daytime running lights (DRL) or the headlights. Any function or condition that turns on the headlights will cancel the daytime running lamps operation. With the headlight switch in the OFF position, the headlights will either be turned ON or OFF, after an approximate 30 second delay depending on whether daylight or low light conditions are sensed. The HTR A/C IGN fuse in the underhood junction block supplies ignition positive voltage to the daytime running lamp (DRL) relay coil circuit. The DRL relay switch contacts are connected to the low beam circuit. When the headlamp switch is placed in the OFF position, the BCM will either turn on or off the daytime running lamps, depending on whether daylight or low light conditions are sensed. The BCM energizes the DRL relay, closing the switch contacts and grounding the low beam circuit. Ground is provided at G101. The DRL illuminate the low beam headlights at a reduced intensity. The DRL will operate when the ignition switch is in the ON position, the gear selector is not in the PARK position and the parking brake is released. When these conditions have been met and the ambient light sensor indicates daytime conditions, the DRL will illuminate.
There is a DRL (Daytime Running Light) Module located in the Fuse Box area under the hood, just remove it and purchase a new one and your DRL's will work fine again.
The wiring diagram does not show a stand alone drl module for the 03 f150. However it shows 2 drl
relays located in aux. relay box #2 located behind the right side of the dash, left of the glove box.
Also there is the drl resistor located behind the grill, right of the left headlight. Relay #1 is fused at
fuse #5-15a in the fuse block under the left dash. Relay #2 uses fuse #26-10a under left of dash.
Hope this helps.
Check under the hood where all the fuse boxes are located and you will need to find the DRL Module, it is a rectangular, squarish black plastic module, pull it straight up to remove it and purchase another one and install.
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