Low Beam Headlights Don't Work

Reply Subscribe

Thread Tools

Search this Thread

Jul 13, 2006 | 10:49 PM

bawbaw

Thread Starter

New User

Joined: May 2006

Posts: 5

Likes: 0

Low Beam Headlights Don't Work

Please help! I have a '99 F150 4x4 with manual lights. I also have factory fog lights in the bumper. Neither low beam or fog light will work. All dash lights do work except the little fog light indicator in the light switch. I can shift into high beam and the headlights will work. The DRL work. I have recently change the turn signal MFS and wire harness to the MFS (this was a turn signal related problem). I checked both fuses to the low beams (#26 and #28) and they are not blown. Any suggestions would be greatly appreciated.

Jul 14, 2006 | 02:36 AM

87 XLT

Postmaster

Joined: Oct 2003

Posts: 4,516

Likes: 1

From: SoCal

If your truck is equiped with the lamps out warning system the lamps out module/LOM is probably shot.

Only the low beams are wired thru the LOM.

Jul 14, 2006 | 06:24 AM

bawbaw

Thread Starter

New User

Joined: May 2006

Posts: 5

Likes: 0

Thanks for the reply! How do I know if my vehicle has a lamps out module, what does it do and where is it? Does anyone know if the fog lights run through this module also?

Jul 14, 2006 | 03:05 PM

87 XLT

Postmaster

Joined: Oct 2003

Posts: 4,516

Likes: 1

From: SoCal

I only have the factory wiring diagrms for the Ford's that I own & I dont own a 99 F-150

According to what you have checked or replaced, it sounds like a bad LOM.

But thats only if your truck is equipped with a lamps out idiot light on the dash or wherever.

Have you got a wiring diagram for the headlight circuit? The wiring diagram would make figuring this out VERY simple.

Edit, BTW, theres been quite a few posts about guys finding loose coonector pins in the LOM & resoldering them instead of spending 80 bucks for a new one.

Last edited by 87 XLT; Jul 14, 2006 at 03:15 PM.

Jul 14, 2006 | 03:10 PM

bawbaw

Thread Starter

New User

Joined: May 2006

Posts: 5

Likes: 0

I do not have a wiring diagram. I have Googled it but do not find anything. Do you have any ideas where I might find one? Thanks again for you response.

Jul 14, 2006 | 03:25 PM

87 XLT

Postmaster

Joined: Oct 2003

Posts: 4,516

Likes: 1

From: SoCal

You might find an online wiring diagram at autozone.com

Or, you can probably get the factory wiring diagrams on E-bay. Or at helminc.com

Thats where I got mine & theres nothing better for figuring out electrical problems.

Jul 14, 2006 | 08:42 PM

Franklin2

Moderator

Joined: Jan 2001

Posts: 57,025

Likes: 2,756

From: Virginia

I am looking at the 99 diagram. The power runs from a main fuse to the headlight switch. From the headlight switch it travels on a red/yellow wire to the multi-function switch. The multi-function switch selects high or low beam. The low beam power leaves the multi-function switch on a red/yellow wire also. The high beam leaves on a grey/darkgreen.

So this is the first place to check, the steering column.

The red/yellow low beam wire runs out of the steering column and goes to DRL(daytime running lights) relay if you have DRL's. It goes to a jumper if you do not have DRL's. The DRL relay is located in a DRL relay block which is mounted way up under the dash, near the base of the windshield, behind the glove box.

After it goes through the jumper, or through the DRL relay, it changes to red/black. The red/black goes to the fuse box under the dash were it feeds fuse #28 and #26. It also feeds #27 which is for the foglamps.