Hi there,

I have a 98 F150 and my low-beam headlights quit working this morning. I searched this forum and couldn't find any recent threads about this problem so I started a new one.

All of my other lights function as they should (parking lights, turn signals, tail & brake lights and even hazards). I replaced the Multi Function Switch and still no low beam headlights. High beam headlights work fine as does the flash to pass function. I have checked all of the fuses and they all look good. When I replaced the MFS I noticed that one wire has been spliced with a crimp butt connector but that wire was on the top plug (I didn't think that wire had anything to do with the lights, light wires appear to be in the lower connector). Headlight bulb filaments appear to be intact, and it's doubtful that both would burn out at the same time anyway, unless I'm wrong (I was wrong once, many years ago, can't remember what I was wrong about...). It's winter here in Michigan so I didn't take the time out in the cold to get out my test light, but that may happen tomorrow (hopefully it'll be a bit warmer outside). Since the high beams work I doubt it's a ground issue.

I'm just wondering if there some secret relay or fuseable link that I should look for? REEEEAAALY hoping for a simple fix on this. Any and all tip's and advice will be appreciated!

P.S. I know this is somehow Karma. Just yesterday at work I was complaining about all these people that drive with their high beams on that won't dim their lights for other drivers. Yup, now all I have is high beams. Guess I'm one of them ###holes now.

 

Did you check the low-beam relay?

 

Where did the Ford engineers hide the Low Beam Relay?? My truck does not have daytime running lights or Fog lights.

 

Still no low beam headlights. I replaced the Light switch today and that didn't help. Brand-new MFS and Headlight Switch and still no low beams. I'm not getting any power to the bulb connector on low beams, but showing power on high beams (obviously) Is there a Low Beam Relay somewhere on a 98 F150 without DRL, auto headlights or Fog lights?

Could really use some help on this......

 

Stop throwing money at a problem, it wont help. Get a DMM and print this out, and have a field day:

http://www.mediafire.com/view/mtyvhv...+Schematic.pdf

 

Is there a Relay? Where would it be located? I find relays under the cover on the top passenger side of the dash. There are more relays in under the hood on driver side in the Power Distribution Block, and more relays in a smaller block next to the PDB. My owners manual doesn't tell me what the relays are for, it only gives me numbers (for the PDB and fuse panel under driver side dash). I have heard their may be a headlight relay on the steering column???

 

There is no 'low-beam' relay according to that schematic.

HOW Did you check the fuses - in particular, the two low beam fuses shown lower left of that diagram in the 'Junction box - fuse relay panel' ( yer Owner's guide will tell you where that is). Fuses # 26, # 28 - hard to read - again OG will give you #'s. 10 Amp fuses.

Just looking at them is pointless - you need to check with a voltmeter from each test pin on the back of each fuse to a known good ground. Should be ~12v at each point with the headlight switch in the on, and MFS in the lowbeam, position.

If yer highbeams are working, this means the feed fuse - 30A at the top - is fine. and if you already changed the main light switch and MFS those are also likely fine.

IF the two lowbeam fuses check out, This leaves the wiring to the sockets, the sockets themselves, or the lowbeam filaments are all that's left to check. I was hoping for something common, too - 2 fuses popping at once is troubling.

EDIT - just found this using Advanced Search ( there are many more) - it may help: https://www.f150online.com/forums/el...m-97-f150.html

[Point here being - while there my not be any recent threads ( e.g. nothing found by scrolling through a couple/few pages of threads) there will almost 100% already be info regarding yer issue on a site like this, with more than a 13 years of archival knowledge, ready to be properly searched with a search tool - either the site's own or Google. Just fyi fer future reference, and problems ]

MGD

 

I checked the fuses with a test light (even replaced the two 15a low beam fuses just to be sure). Test light lit up brightly at each side of fuses. I tested the socket connector at each headlamp with a volt meter, got 12.7v with high beams on and nothing with low beams on.

I have searched threads as far back as 2009, still haven't found anything that I haven't checked.

At this point, I cheated and re aimed the headlamps. Now my high beams are low beams. This should get me by until I can find the problem.

Anybody know where I can get an authentic Chrystal Ball and Magic Wand???????

 

I think its time to start tracing out wires and looking for a break or ohming the wires..

 

That thread I linked was from 2007 - they go back a lot earlier too - but yer right - given the circuit's simplicity yer running out of stuff to check - almost.

This your truck from new? Reason I ask is, those two fuses are supposed to be 10A, not 15A. And yes, I just checked a 1998 manual ( page 137) to confirm that. So - the circuit is 50% overfused and a bit unsafe.

If you bought the truck used, this leads me to believe someone replaced those fuses with something larger for a reason ( speculating here ). Now I suspect harness damage somewhere. You didn't do it, right?

So - first principles again - you know where all the components are, you have a voltmeter, you have a schematic with colour codes, so go to each component, starting with the main headlamp fuse (30A) and confirm each segment for voltage/continuity, backprobing connectors as you go and actuating switches as necessary, until you reach the lowbeam lamp socket pin. Ensure a good ground is used for the meter.

If you don't find the culprit this way, I dunno what else to tell ya, as that approach has never failed me. No magic wand required - just patience and brownpops.

MGD

 

I bought this truck used a couple years ago when, after 21 years and 240,000 miles, the transmission went out in my old 90 Chevy.

There were 15a fuses in it. I didn't notice that they should be 10a. No, I didn't do it.

I have seen the schematic but it's hard to read on my 'puter. Tried enlarging and printing it out but that didn't help. I drive past a local Ford dealer every day going to work. I'll stop in there tomorrow and see if they have a schematic I can copy. Maybe one of the tech's can offer some tips too?