headlights dont work

[Tinovolpe]

Hoi everyone. Got a 2001 dohc Taurus. Noticed my right headlight was out so took headlamp assembly out and put new bulb in. Now the headlight dont work. Parking lights work, hi beams work and flash works but regular lamps no, not even in auto mode. All fuses, 29,19 and 21 are good. Any ideas? The headlamp switch was changed a few years back. Changed the blend door actuator a month ago and found out sunload sensor was bad but that should only affect auto lamp function, correct?
Any ideas folks? Don't want my sun driving around with high beams on all the time.

[65comet]

There are relays for the headlights that can go bad. Usually a low beam and a high beam. I'm not sure where or which number position they are for your year. You'll have to search for that. What I normally do is swap the high for the low as they are usually the same relay and if your low comes back and your high is out then you know you need a new relay.
My first thought was the switch, but you said you changed that. But don't assume the new one was a good quality and hasn't gone out already.

[Tinovolpe]

THanks. I was wondering about the relays. Was searching other posts and forums and a lot of conflicting info out there. Some say 2001's have no relays, others say they have them but are on the printed circuit board so can't replace easily. Others say they are by the battery and others saw they are under the dash. WTF? Does ford make that many different combinations or are people just confused. The service manual for this car says that if low beams are inoperative look at the multifunction switch, if high beams are inoperative look at headlight switch. That seams backwards. What does the headlight switch have to do with the high beams?

Thanks

[Tinovolpe]

Hey I was wondering. Would this issue occur if I didn't plug the connector back in all the way when I reassembled the headlamp assembly? Now my kid says the gas gage isn't working right and his cassette player gives an error message. Coincidence?? What would happen if the headlamp connector (not the bulb) wasn't pushed in all the way?

[Tinovolpe]

For everyone's information I changed the mutifunction switch on the steering column, which was actually pretty easy and now the low beams work as well as everything else. Guess it was a coincidence that it went out when I happened to changer the lightbulb, which threw me for a loop.

Thanks

[65comet]

Sorry, when you said switch had been replaced, I assumed you were talking about the multi-function stalk since it is the one that usually goes bad. The spring contacts to go from high to low will spark, and over time melt the plastic around them. Either the plastic builds up preventing contact or it pushes against the contact springs and they no longer will push the contacts into place.

[Tinovolpe]

Bad news. The low beams worked for a few hours. Then same problem. Wondering if I'm dealing with a short somewhere

[shorod]

If you're comfortable reading a wiring diagram, I can send you the headlight wiring diagram. If interested, send me a Private Message with the request and an e-mail address for you. You mentioned autolamps, so a reminder that your car has that would limit the number of diagrams I need to send.

-Rod

[Tinovolpe]

Thanks!! The car does have the auto lamp feature. I also get a code telling me the sun load sensor has failed. I'll send you a pm

[shorod]

The files should be on the way to your inbox.

-Rod

[Tinovolpe]

Thanks for the wiring diagrams. Not the greatest at reading them. However I rechecked all the fuses and they are good. There is power to both legs of fuses 19 and 21 in the engine compartment with everything off. Fuse 29 under the dash is also good and there is power to just one leg with everything off. I pulled the headlight assembly and disconnected the plug and checked for power on each of the 6 pins under various conditions, lights off, lights on, highbeams on, and parking lamps on. Parking lamps work just fine by the way. I attached a diagram showing which pins were hot under which conditions.H stands for hot. Any clues?

[shorod]

I'm going to arbitrarily number the pins in your diagram like you would read a book. Pin 1 should be a Red/Black wire, pin 2 is Dark Green/Orange, Pin 3 is Light Green/Black, Pin 4 is Brown, Pin 5 is White/Light Blue, and Pin 6 is Black. The functions of these are as follows:

Pin 1 = Ground for Low beam and Flash to Pass
Pin 2 = Headlight Power from the fuse
Pin 3 = Ground for High beam and Flash to Pass
Pin 4 = Power for Parking lights
Pin 5 = Ground for Parking Lights
Pin 6 = ?, but shouldn't matter in this case

So based on this information and your diagram, I'm concerned that you are measuring power on pin 3, unless that's feedback through the headlight bulb on the other side. Did you have both headlight assemblies disconnected or only one side? If only one side, how difficult would it be for you to disconnect both sides and repeat the measurements? Also, confirming which wires have true ground (not just floating) in each of the conditions would be helpful. In particular, confirming when, if ever, you have ground on Pin 1. Using an old school test light would be great, although you'd need to switch the clip between power and ground for the measurements, but at least it will confirm a good ground versus just floating.

Otherwise, the measurements you made make sense for the parking lights and high beams. In your low beam test though, Pin 3 should not be measuring battery voltage, it should be measuring Ground for the low beam headlights to work.

I suspect that you'll ultimately find that you are never getting a good ground on the Red/Black wire. In that case, you'll need to trace the circuit through the Multifunction Switch (MFS), through the headlight switch, to ground. Since the highbeams work correctly I think you can rule out the ground to the headlight switch and, really, the headlight switch completely. That really only leaves an issue with the wire between the MFS and the low beam filament (Red/Black wire) or the MFS. If your tilt steering wheel sees a lot of use, maybe the wire is broken in the steering column. When you replaced the MFS last time, you jiggled the wire enough that it made contact again, but after a bit of jiggling while driving, the wire opened back up. You should also check the terminations at the plug to the MFS. In the Ford Explorers from the '90's it was pretty common that the wires to the MFS were too short and constantly strained to the point where they would pull loose in the connector or break.

-Rod

[Tinovolpe]

Rod,

Your wiring analysis is right on the mark. The pin wires were colored just as you described. I repeated my test with both headlamps disconnected and got the same result. Now here is the part where I have to throw myself on a sword and apologize profusely. My kid was helping me with the testing and reading the wiring diagram when he happened to mention that after I replaced the burned out bulb initially the headlights worked when he went to a friends house. It was when he was returning that they didn't. So that caught my attention and made me wonder. When I changed the MFS, I never went back and checked the bulbs. I just assumed the MFS switch was bad, not that it would short out the bulbs. I pulled the two bulbs and checked continuity and got none. The bulbs were bad. So I ran to the auto store, got two new bulbs put them in and they work. In the end it was the MFS that went back, which is the same conclusion you just reached. Something in the old MFS must of went bad shorting out the bulbs. So I apologize wasting your time. but you did teach me (and others I hope) a lot about how these headlight systems are wired.

[shorod]

No problem, I'm glad you got the issue resolved and have the vehicle safe for your son.

-Rod

[65comet]

I know the feeling. After a rewiring I accidently put 6 volt bulbs in a 12 volt system. Took 3 days of wire checking for a short before noticing they burned out because of the type of bulbs there were and not a short somewhere in the new system.