auto-lamp function - '03 Sport Trac

the Auto-lamp seems to turn on the lights as necessary, but I've noticed that when the headlight switch is in the "off" position the headlights are dimmer than when it is in the full "on" position (manually switching the lights on). It's almost as though the autolamp is turning on the dash lights but not stepping the headlights up from the daytime running lights.

Has anyone else seen this, or am I not using the autolamp function properly?

D.

I'm not familiar with the '03 lighting system with Daytime Running Lamps (DRL), so I need some clarification.

With the headlight switch in the "off" position, the DRL is activated, right? The DRL operate in full daylight, and in the dark if the switch is left in the "off" position. However, if you turn the headlight position to "on," the headlights appear brighter than with the switch in the "off" position.

With the switch set to "off," and the autolamps enabled, when it gets dark, the autolamps turn on the instrument panel lights (which are normally off with the DRL on but the Autolamps off) but the headlamps seem to remain at the DRL reduced intensity?

Are you certain that the instrument panel lights are off when only the DRL is active, and that the Autolamps are properly enabled?

-Rod

Hi Shorod,

Yes, the instrument panel lights are off during normal daylight operation. I can't say for sure if the nighttime lights are brighter than the DRL, but I can be sure that they are not as bright as when I manually switch the lights on. I'll see if I can check that tonight (DRL vs lowbeams in Autolamp mode). Once the Autolamp has switched the lights on, I get fog lights and highbeams, which I wouldn't have if only the DRL were on (during daylight operation).

Further fiddling and experimenting with it, I've also found this to be true with the high beams - again, brighter than low beams, but brighter still if I flip the headlight switch to "on" rather than relying on the Autolamp feature.

To be clear, the autolamp seems to be functioning properly in terms of activating and de-activating the nighttime lighting systems, it just seems to be running the headlights at reduced power. And the difference is probably only about 10-15% in brightness. I just find it odd that there is any difference at all.

It would appear from the wiring diagram for the 2002 Sport Trac that the low beam and DRL are both powered through the DRL module. It also appears from the diagram that the DRL module may be a solid-state device. If the DRL module uses a solid state relay or SCR for the driving lights and headlights, I could understand how the autolamps may be a different intensity from just turning on the low beams from the switch.

The DRL could be malfunctioning and either not providing enough voltage/current to the low beam filaments on autolamp.

-Rod

I haven't seen the wiring diagram, but if the autolamp bypasses the DRL in some way then maybe it could be a grounding issue with the autolamp.

Denis

Rod,

Further to your earlier questions - at night, if I switch off the Autolamp feature, while the headlight switch is in "off" position, the interior lights switch off, along with fog lights or high beams (if they were engaged) but the intensity of the low beams does not change. To me, this says that the autolamp is only powering my headlights as DRL during normal operation.

I'll take your comments about the relay or the ground to the shop when I next have it in for something more significant.

Much appreciated!
Dave

That was a good check, and it sounds like you are on the right track. Unfortunately I've never had one of the DRL modules apart to reverse engineer.

-Rod