Headlight prob. - Diesel Forum

Barebackcwby2003 · 09-03-2005, 11:42 AM

I suppose this is a common issue? my headlight switch needs to be replaced, when I disconnected it from the harness in the dash, the plastic around one connector was melted and burned a little. Ran accross a 93 f150 today in a junkyard, and had same problem with its connector, just different contact, and much worse of a melting issue. What will cause this? just a bad switch, something in the system, not throwin the fuses? I didnt have the truck long enough to find out about this prob. I installed 2 Sylvania Silverstar bulbs, n the next night I started to lose just my headlights, but would come back on. I got a NEW FORD switch, but at 30 bucks, n no return, I dont need to go blowin these things up, to find its not the problem! Also, my headlight "dinger" started to malfunction last night, it just stayed on, My door jamb switches are disconnected, I do have a wire hanging on my column, looks like it goes to the ignition, perhaps my "dinger" problem. Dont know though. Any info will help. But I need it fixed, like.... YESTERDAY! [img]/ubbthreads/images/graemlins/shrug.gif[/img]

Dalvaras · 09-03-2005, 06:23 PM

the headlight switch burnning up is a common problem on our trucks. It is because the switch has full power dram of the lights going thruogh it. There is a fix for it right here http://www.ford-trucks.com/article/i...r_Brights.html

Barebackcwby2003 · 09-03-2005, 08:50 PM

OHHHH I understand now. Thanks alot! im going to get to work on that lil solution!

krawlr · 09-04-2005, 11:41 PM

Once you get your relays in you can get a replacement plug for the light switch. I've seen them in the carded "Help!" section at most parts stores or Napa should have them too.

What is the color code on your mystery wire? I have an AllData account and I can pull the wiring diag. up.

Carmine · 09-05-2005, 10:41 AM

Hi,

Ah yes, this was one of the first things I had to fix on my truck. NAPA does carry a replacement harness. If you search for my name you will find a post where I called out the part number. It is about $10 and is easy to install. Use solder and shrinkwrap and take your time.

I agree that a hearlight relay should have been used on our trucks, not sure what brain-surgeon-wannabe at Ford decided not to.

When my switch burned I did a little post-mortem on the situation. What I discovered is that the contact responsible for the burn is the instrument cluster dimmer. To dim our dash and instrument lights a large, wire-wound potentiometer is used. It acts as a voltage divider (bear with me, this is the engineer talking) and, in the process, creates a tremendous amount of heat. I found the switch terminal leading to the dimmer winding to be discolored and softened from the repeated heating and cooling. It, along with the receptacle in the harness, had annealed. This results in a bad contact with additional heat generation and the whole thing just snowballs.

Anyway, since I discovered this I NEVER EVER EVER use the stupid dash dimming capability. Run all the curent to the instrument lamps, dont send any through the pot and it won't get hot.

My new harness has been in there since, oh, maybe '96 or so.

Carm*

Barebackcwby2003 · 09-05-2005, 09:59 PM

Thanks for the info guys, Unfortunatly I was left with no choice but to install my new, Motorcraft (yeah I know, WHY?) switch before the relays, but I need front rotors, n fuel lines, an the list goes on. Hopefully I dont burn it out before the relay install. I will get the wire color for ya.
Back to the Motorcraft, Ford stealership deal, for the price I paid for this truck (CHEAP!), Im not skimping on ANYTHING! I'll pay the extra buck for factory things. SOME factory things. [img]/ubbthreads/images/graemlins/grin.gif[/img]

Carmine · 09-06-2005, 07:56 AM

The relays are nice but the new switch harness is a MUST.

If you use the old one you stand a good chance of burning it even further. The "springiness" of the burned female connector in the harness is gone now. This will make for a poor connection which will generate heat.

You'll end up toasting your nice new Stealership switch in the process.

And remember - no dimming of the dash lights! [img]/ubbthreads/images/graemlins/wink.gif[/img]

C*

Barebackcwby2003 · 09-07-2005, 09:38 PM

Hey thanks Carmine! Oh dont worry bout those big engineering words. My father works for BAE Systems installing/upgrading/designing and fixing Automated landing systems on US Navy aircraft carriers (n I have done some work in his division before [img]/ubbthreads/images/graemlins/wink.gif[/img] ) So I know what yer talkin bout. I will research yer past posts, n fix up that wiring issue. Thanks again for all yer help guys. Everyone on here has been very helpful and patient! [img]/ubbthreads/images/graemlins/cool.gif[/img]

guntherx2000 · 09-08-2005, 12:14 AM

I did the relays upgrade and bought both relays for under $20 and did the whole job in under an hour. BIG improvement.

Along these lines; does anyone know anything abouth a something called an instrument voltage regulator? i read a small piece about it on another sight. It supposedly resides behind the instrument cluster. When I test my amperage output and the voltage at the battery, all tests well, but I see a rapid flickering that is barely perceptable in ht edash lights, radio, etc. Any ideas?