My low beam headlights will not shut off. I think it is the DRL module but I can not find it on my 2003 Excursion. Can any one help me with a location? I also have a 2003 F350 and there are quite a few differences in the wiring harness and components so it is of little help. I have tried the easy stuff like the headlight switch and the multifunction switch to no avail. So far the only things that will shut off the lights is a battery disconnect or pull both headlight fuses.

 

The 03 Super Duty line, both the truck and the SUV which should be the same depending on options, does not have a DRL module. The function is implemented using what is basically hardwired logic using relays that switch in a current-limited power source to the low-beam circuit when conditions are correct.

The simplest way to disable the feature and prevent battery drain is to pull DRL Relay #1 in the Auxiliary Relay Box #2 under the hood while you figure out what's wrong.

 

Thanks for the help. I will look for the relays you mentioned. Do you know where I could get a diagram that identifies under hood components? I think I know where the two small relay packs you are referring to are (near the master cylinder) but don't know which is which.

 

If the factory service manual is to be believed:

1. The subject box is the upper of the two boxes back in the corner between the master cylinder and the fenderwell.
2. Open the box, there should be three relays. Visualize the layout so that the single relay (DRL #2) is at the top. Of the two relays that are side by side, DRL #1 is on the right and the DRL Parking Brake relay is on the left.

BTW, do the DRLs go off when the parking brake is applied (suppose to...)?

 

Found it. It is just as you said the manual indicates. I did not know the park brake is involved. When I pull all or any of these relays the lights stay on. I found a wiring diagram titled 12-34 elsewhere in this forum and it seems to help me understand the current path. 12-34 is for 2000 - 2002 Excursion with DRL mine is a 2003. The wire count and color depicted in 12-34 does not exactly match my 2003 so I have not considered it inerrant but instead as very helpful in tracing the current path from component to component. I removed the main junction block near the e brake pedal and looked for any damage or sign of heat and found none. There are about 13 single wire or multipin connections and I found the one feeding constant power to the two headlight fuses. When I unplug this connector the lights go off. found the wire on this connector and it is black with a red stripe, inverse of the colors that are shown on 12-34. This wire does not appear on the connections at the DRL relays. ??? Next I will take the column apart and unplug the multifunction switch and look for a black with red stripe or damage around there.

 

I suspect the diagram you found is not applicable to your vehicle. I'll see if I can dig up the correct ones.

 

I just removed the multifunction switch. Inspection revealed no visible problems but I did find the same color wire that I found errant current on at the main junction box. When I unplug that multipin connector from the multifunction switch the headlights go out. I think I just unplugged the other end of the same wire so I don't know how conclusive it is. Still have not found the DRL resistor and still can not confirm that my set up has one as illustrated in 12-34 diagram. I have never seen my headlights operate at reduced output and they are at full brightness now during this fault.

 

Since you didn't actually link to that diagram or identify wires by either location or color, it's impossible to comment on what you're seeing.
That would indicate that the DRL circuits are not causing the headlights to stay on.

 

I would agree. DRL relays do not seem to be a part of the problem. I wish I could link to the diagram I have been referring to as 12-34 but I am not computer savvy enough to do it yet. I have attempted a link below. I have ordered a new multifunction switch and will install it Wednesday night. I will post the results so all can see if this remedy is successful https://cimg4.ibsrv.net/gimg/www.for...f7ee3e03b0.jpg.

 

Unfortunately, the image is two small and too low of resolution for me to make out details.

It is highly unlikely that the MFS is the issue. Back in your first post, you stated "I have tried the easy stuff like the headlight switch and the multifunction switch to no avail.". What exactly does "tried" mean? What new information prompted you to revisit the MFS?

Time to take a better inventory of symptoms:

1. Is the truck equipped with Autolamp?
2. Are you positive that only the low-beams are on when the headlight switch is turned to OFF?
3. While in failure mode, what happens when the MFS is put in the high beam position? How about the flash-to-pass?

 

After looking around a bit at an old Chilton repair manual I have for some Expeditions that I own I recognized the diagram is from a Chilton repair manual. The similarities are unmistakable. I would agree that the MFS is a low percentage guess. In conversation with a friend last week I said in passing that I would give it a 2% chance of being the problem. However when I first considered it my friend and I noticed that the rotary wiper switch at the end of the MFS was a bit loose and so I would like to replace it as I have put a lot of effort into this vehicle and it is now in very good condition. Also any time I see a small defect so close to the current path I am trying to diagnose it makes me reconsider my original pass over of the MFS. The wires and connections all look perfect no sign of any corrosion or heat, that is why I passed it over in the beginning. This Excursion is a Limited so it did come with factory autolamp option. Only the low beams are on when they should be off and the flash to pass, hazard flashers and high beams all work only when they should. I first discovered the low beam problem when after not driving the car for 6 day and it failed to start, I therefor put a battery charger on the Excursion selected a bigger truck and drove to church. Upon returning home my good wife told me the Excursion lights were on and so I shut off the battery charger and thought - the lights were left on and that ran the battery down - until I looked at the light switch and found it was as it should be in the auto position. Soooo.....game on. I received my new MFS today (2 days early) so I will install it and post the result.

 

After changing the MFS the problem still persists.

 

1. Yes it has autolamp
2. Yes only low beams on headlamp switched off.
3. When MFS is high beam only the high beams (low beams turn off) flash to pass works normally (both high and low beams)

 

Since you have autolamp, have you gone through any diagnostic for that feature?
Maybe a bad sunload sensor on the dash facing the windshield?

 

I think autolamp can be ruled out. When active, it simply feeds power into the MFS just as if the headlight switch was placed in the HEADLIGHT ON position for the duration of their activation.

An additional observation: Compare the intensity (brightness) of the low beams when the headlights are turned OFF (but lows are on anyway) with how bright they are when the headlight switch in in the ON position and the MFS is in the low-beam setting. Same brightness or do they get noticeably brighter when the headlight switch is ON?

While you're at it, take and post a photo of each of the following locations: 1) Inside of engine compartment directly above the driver's side headlight and 2) the corner area inside the engine compartment between the master cylinder and the inside wheel well.