Headlights

Tiny
THECROWX
  • 2002 FORD F-150
  • 4WD
  • AUTOMATIC
  • 210,000 MILES

The headlights come on by themselves with nobody in the truck. The truck has been parked for a week, nobody in the truck, headlight switch in the off position, the keys were not in the truck. I had to pull the fuse to shut them down.

The truck has auto lights. The headlights come on and off by themselves with the truck sitting in the driveway unattended. The headlight switch is in the "off" position when this happens. No key in the ignition, and happens anytime, day or night. They stay on for a few minutes, then turn off, several times a day/night. This is driving me crazy. Nobody knows what is causing it. Help! Help!

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Wednesday, December 22nd, 2010 AT 6:37 PM

31 Replies

Tiny
KHLOW2008
  • EXPERT
  • 42,074 POSTS

Here are the diagnostics:

TEST F: HEADLIGHTS ALWAYS ON

1. Turn ignition switch to LOCK position. Remove central junction box fuse No. 16. Central junction box is located under left side of instrument panel. Turn ignition switch to RUN position. If headlights are still illuminated, check for short to voltage in Light Green/Black wire between central junction box and headlights. If Light Green/Black wire is okay, go to next step. If headlights do not remain illuminated, go to step 12.

2. Turn ignition switch to LOCK position. Remove central junction box fuses No. 26 and 28 (both 10-amp). If headlights remain illuminated, reinstall fuses and go to next step. If headlights go out and vehicle is equipped with DRL, reinstall fuses and go to next step. If headlights go out and vehicle is not equipped with DRL, go to step 6.

3. Remove DRL relay No. 2 from DRL relay block. If headlights go out, go to next step. If headlights remain illuminated, repair wiring as necessary between DRL relay No. 2 and central junction box.

4. Test DRL relay No. 2. See MICRO ISO RELAY under COMPONENT TESTS. If DRL relay No. 2 is okay, go to next step. If DRL relay No. 2 is defective, replace DRL relay No. 2.

5. Measure voltage between ground and DRL relay No. 2 harness connector terminal No. 2 (White/Black wire). See Fig. 4. If voltage does not exist, go to next step. If any voltage exists, repair short to voltage in White/Black wire between DRL relay No. 1 and DRL relay
No. 2.

6. Disconnect multifunction switch 7-pin harness connector C202b. Measure voltage between ground and multifunction switch harness connector C202b terminal No. 2 (Red/Yellow wire). See Fig. 3. If voltage does not exist and vehicle is equipped with autolamps, go to next step. If voltage does not exist and vehicle is not equipped with autolamps, go to step 11. If any voltage exists, repair wiring as necessary between multifunction switch and central junction box.

7. Remove headlight relay. Headlight relay is located in RPO relay block No. 1. Test headlight relay. See MICRO ISO RELAY. If headlight relay is okay, go to next step. If headlight relay is defective, replace headlight relay.

8. Disconnect autolamp module harness connector C287. Disconnect Central Security Module (CSM) module 22-pin harness connector C274b. Remove parking light relay from RPO relay block No. 1. See Fig. 10. Measure voltage between ground and headlight relay harness connector Light Green/Yellow wire. If battery voltage does not exist, go to next step. If any voltage exists, repair short to voltage in Light Green/Yellow wire between autolamp module and RPO relay block No. 1.

9. If headlights remain illuminated, go to next step. If headlights are not illuminated, check headlights while connecting CSM module and autolamp module. If headlights illuminate after connecting CSM module, replace CSM module. If headlights illuminate after connecting autolamp module, replace autolamp module.

10. Measure voltage between ground and multifunction switch harness connector C202b terminal No. 2 (Red/Yellow wire). See Fig. 3. If voltage does not exist, go to next step. If any voltage exists, repair wiring as necessary.

11. Test multifunction switch. If multifunction switch is defective, replace multifunction switch. If multifunction switch is okay, replace headlight switch.

12. Disconnect multifunction switch 7-pin harness connector C202b. Measure voltage between ground and multifunction switch harness connector C202b terminal No. 5 Gray/Orange wire. See Fig. 3. If any voltage exists, repair short to voltage in Gray/Orange wire. If voltage does not exist, replace multifunction switch.

MICRO ISO RELAY

1. Check relay continuity. Continuity should exist between relay terminals No. 1 and 2, and between relay terminals No. 3 and 4. See
Fig. 8. Continuity should not exist between relay terminals No. 3 and 5. If continuity is as specified, go to next step. If continuity is not as specified, replace relay.

2. Using a jumper wire, apply battery voltage to relay terminal No. 1. Using a second jumper wire, ground relay terminal No. 2. Continuity should now exist between relay terminals No. 3 and 5. If continuity is not as specified, replace relay. If continuity is as specified, relay is okay at this time.

MULTIFUNCTION SWITCH
Remove multifunction switch.
Measure resistance between specified terminals while operating multifunction switch lever to specified positions.
See MULTIFUNCTION SWITCH TESTING table. See Fig. 14. If resistance is not as specified, replace multifunction switch.

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Monday, December 27th, 2010 AT 2:01 PM
Tiny
MMILLS42
  • 2002 FORD F-150
  • 5.4L
  • V8
  • 4WD
  • AUTOMATIC
  • 123,000 MILES

Today I tried installing new halo headlights in my truck. Started out well, but then I couldn't get my running lights to come on and my low beams were stuck on. The fuse for the left low beam was bad but it still stayed on even with the bad fuse in. So now when ever I turn the low beams on they will come on but I can't turn them off. Someone please help. I don't know if another fuse is bad or if its something with the actual connectors to the headlights. My switch for the headlights does not work anymore to turn them off only works to turn them on

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Wednesday, October 25th, 2017 AT 2:12 PM (Merged)
Tiny
HMAC300
  • EXPERT
  • 49,774 POSTS

Check relays for headlights then recheck everything you did it may be that the halo lights are not compatible with your vehicle.

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Wednesday, October 25th, 2017 AT 2:12 PM (Merged)
Tiny
MMILLS42
  • MEMBER

What if I hooked the stock lights back up and it was doing it with them too? I had the actual halo headlights ( just the low and high beams) hooked up already and they were working fine. Its just when I went to splice the halo rings into the parking lights that all of this started happening. I haven't checked the relays yet and I'm thinking also it could have been I pulled the wiring too hard when taking the headlights out of the seeding.

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Wednesday, October 25th, 2017 AT 2:12 PM (Merged)
Tiny
1ROMAN
  • 2002 FORD F-150
  • 2WD
  • AUTOMATIC
  • 110,000 MILES

I just replaced my brother in laws headlights on his truck for after market upgrades with built in led halos and DRL's. The headlights are one complete unit and replaced the separate direction indicator and headlight units. His old set up was one bulb for both low and high beams his new set up is projector low beam lights and separate high beam light ( two different lights in the head unit two separate bulbs.) The issue is that the low beams work fine but when the high beam is activated the low beams go out and only come back on when the high beam is turned off. The inbuilt DRL's have been wired to only come on when the ignition is on.

What can we do to make the low beams stay on when the high beam is activated?

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Wednesday, October 25th, 2017 AT 2:13 PM (Merged)
Tiny
CARADIODOC
  • EXPERT
  • 28,980 POSTS

You are not supposed to have both at the same time. Low beams light things up close to you. Your eyes adjust automatically for that. If the high beams are used at the same time, they will not do any good because your eyes have adjusted to the brighter light. That is the same thing that gives people the false sense of better night vision with the HID lights that belong on poles in parking lots. Your eyes adjust to the brighter light, and that makes them less sensitive to night driving. If you doubt that, try driving by bright moonlight with the vehicle's lights turned off. It is pretty easy. This is also why all factory-installed fog lights turn off when the high beams are on.

The other problem is a pair of standard bulbs draws ten amps on low beam and twelve amps on high beam. The contacts in the dimmer switch and head light switch are supposed to be able to handle a little over twelve amps. For years Ford has pushed the limit on how much their switches can handle. The slightest arcing will cause the contacts to overheat, and that progresses until the terminals also overheat, often to the point of causing a fire. To run all four lights at the same time would result in twenty two amps, and switches that burn out on a regular basis.

Head light switches also have auto-resetting thermal circuit breakers built in. Those cause more problems than they prevent, due to arced contacts. Twenty two amps would cause that breaker to trip repeatedly.

Daytime running lamps are another over-engineered gimmick from GM. They decided to run the high beams at eighty percent of full brightness. To do that requires a computer to run a "pulse-width" dimming circuit that is notoriously less reliable than running a simple bulb at full brightness. You are still shining the high beams into people's rear view mirrors, so they have to dim them during the day. What is the point in having the mirror if you cannot use it during the day?

If you think your customers are too stupid to turn on their own head lights, and feel the need to do that for them, it would take a ten-dollar relay to run the low beams when the ignition switch is on. The engineers could not figure that out, and went for the most complicated circuit they could possibly come up with. You can do the same thing with a relay. You cannot just wire the low and high-beam circuits together because both would be on all the time. Instead, let the dimmer switch turn on the low beams, and when they are off, it will turn on the high beams and a relay. Let that relay keep the low beams on. The additional advantage to this is once you realize you cannot see as well things that are far away, all you have to do is unplug the relay, then you are back to normal operation.

You do not even have to use the high-beam circuit to run the relay. You can connect it right to the ignition coil feed wire so the relay turns on the low beams anytime the engine is running. They will stay on regardless if the high beams are on or off.

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Wednesday, October 25th, 2017 AT 2:13 PM (Merged)
Tiny
KURTHUEGEL
  • 1998 FORD F-150

Electrical problem
1998 Ford F150 V8 Four Wheel Drive Automatic 197000 miles

My high beams stay on with the light switch turned off and even with the engine off and key out of the ignition. When I turn on the light switch the high and low beams work correctly. I have changed the light switch assembly and the multi switch with no results.

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Wednesday, October 25th, 2017 AT 2:13 PM (Merged)
Tiny
JAMES W.
  • MEMBER

If you unplug the wire connector from the multi switch and the lights still stay on, you have a cross over short on either the GRY/YEL wire from the multi switch to fuse #16 in the fuse block OR from fuse #16 to the headlights.
If the lights DO go out when you unplug the harness from the multi-switch, the multiswitch is bad.

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Wednesday, October 25th, 2017 AT 2:13 PM (Merged)
Tiny
KURTHUEGEL
  • MEMBER

I have removed most of the dash panels and have followed the wiring and have found no grounds or broken wires. The multi switch is removed and the lights are still on. When I remove the #16 fuse the lights stay on. Should they stay on? The wiring harnesses under the hood to the lights look good. I am at a loss unless the #16 fuse location is bad.

Thanks for the HELP!

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Wednesday, October 25th, 2017 AT 2:13 PM (Merged)
Tiny
JAMES W.
  • MEMBER

No, with the #16 fuse out, you should have no high beams at all.
Check both sides of the socket for #16 fuse. Are they both hot?
If yes, in the power box under the hood, pull #8-30amp fuse. Do all the lights go out?
Let me know.

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Wednesday, October 25th, 2017 AT 2:13 PM (Merged)
Tiny
KURTHUEGEL
  • MEMBER

I checked both sides of the #16 fuse and only the left side is hot. I did pull the #8 fuse under the hood in the power box anyway and the lights did not go out.

Thanks Again

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Wednesday, October 25th, 2017 AT 2:13 PM (Merged)
Tiny
JAMES W.
  • MEMBER

Well, that soots down my first theory. Is the high beam indicator "on" in the dash?
Do you have the DRL option on the truck? (Daytime running lights)

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Wednesday, October 25th, 2017 AT 2:13 PM (Merged)
Tiny
KURTHUEGEL
  • MEMBER

Yes I do have the Daytime Running Lights option. Yes the high beam indicator light and the high beams are on when the light switch is in the off position. When I turn on the light switch I can change from high beam to low beam normally but as soon as I turn off the light swith the high beams and the indicator light turn on. It seems to me that it is the high beams and not the daytime running lights that are staying on.

Thanks

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Wednesday, October 25th, 2017 AT 2:13 PM (Merged)
Tiny
JAMES W.
  • MEMBER

OK, now it's starting to make sense. In your "power distribution block, unplug fuse #9-15amp. If the lights go out, your DRL module is bad. Check it out and let me know, Jim.

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Wednesday, October 25th, 2017 AT 2:13 PM (Merged)
Tiny
LIEUTINENT BILL
  • 2001 FORD F-150
  • 98,000 MILES

Headlights won't turn off when engine is off, have to disconnect battery. Wires look ok, never has done this before, is it relay switches, fuses, light switch? Where do I start and what kind of repair shop does this kind of service

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Wednesday, October 25th, 2017 AT 2:13 PM (Merged)
Tiny
KURTHUEGEL
  • MEMBER

Hi Jim,

Well that turned off the lights so it is a DRL module that is bad. How does that control the high beams? I guess I always thought the DRL were on low beams.

By the way were is the DRL Module located?

Thanks for all of your help.

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Wednesday, October 25th, 2017 AT 2:13 PM (Merged)
Tiny
DOCFIXIT
  • EXPERT
  • 18,985 POSTS

Suspect stuck DRL relay in DRL box under rifgt side dash relay#2 remove see if lights go out. Truck have auto lights or manual?

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Wednesday, October 25th, 2017 AT 2:13 PM (Merged)
Tiny
JAMES W.
  • MEMBER

According to the diagram, both hi and lo beams go through the DRL module. Why, I don't know. The fuse you just pulled is hot at all times and for some reason, that circuit in the DRL module has crossed over to the highbeam circuit.

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Wednesday, October 25th, 2017 AT 2:13 PM (Merged)
Tiny
LIEUTINENT BILL
  • MEMBER

It's manual, thanks so much for a quick answer.

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Wednesday, October 25th, 2017 AT 2:13 PM (Merged)
Tiny
DOCFIXIT
  • EXPERT
  • 18,985 POSTS

Did you remove relay?

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Wednesday, October 25th, 2017 AT 2:13 PM (Merged)

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