Losing low beams on headlights

Tractor Dan · Apr 9, 2013

Ok. 97 ranger. Dual element bulbs 100% stock. I keep having this issue and it's driving me nuts. Haven't had a chance to investigate it much but now i can try.

Basically i'll be driving down the road and lose my low beams. My dash lights and climate control lights for the blower and stuff stay one. So does my radio. Truck never skips a beat running. I just lose the low beams. If i pull the turn signal lever towards me to flash the brights i get brights. If i hold them on long enough and let on and off the low beams come back. So this leads me to believe it's something in that multi function turn signal brights switch? :dunno:

I know the headlight switch is in good shape and tested good from having the dash apart to figure the instrument cluster lights out. So i'm thinking it's either that multi function switch or a ground issue? I pulled the headlight bulbs at christmas and they were fine and i put some bulb grease on the terminals of the connector.

Battery terminals are tight and clean. Just cleaned before easter. Ground from battery to the body up by the radiator looks good. I can clean it i suppose just for good measure but no signs of damage or corrosion. So think check that switch and the ground straps? The alternator is good. Just replaced it in November. All wires look good no cracks or anything like that. Any input is appreciated. I'm trying to chase down what i can. I can't do some wire checking if i gotta get on the ground or climbing around. My hip surgeon would kill me if he found out or if i messed myself up again doing it. :icon_rofl:

Earl43P · Apr 10, 2013

The headlamp switch and its connector / pigtail are notorious for overheating.

I realize it's quite the pain to get to that switch, but I strongly suspect that is exactly what you'll find.

Otherwise, the only othe path in common with both low beams is in fact the Multifunction Switch. I still discount the MFS actually causing your problem.

In the Headlamp switch, a single set of contacts routes power to both low beams (it splits that power into two fuses later in the circuit, after the MFS). When you hit flash to pass, a seperate fuse supplies power to the high beams, and that power path does NOT come through the headlamp switch.

The ultimate deciding factor is this:

When the low beams quit, immediately select high beams, not flash to pass.
If high beams work, replace the MFS.
If high beams don't work, replace the Headlamp switch (and its connector).

As for headlamps grounds, they are not common. In other words, G103 is used for the left, G105 for the right. Hi and Low beams both use the same ground(s), so a ground is NOT your problem.

One other thing that I noticed when researching this in the 93 schematics, there is a circuit breaker installed for the flash to pass power instead of a fuse (not relevant for your problem, but keep reading). That fuse also powered power lumbar and cig lighter. Make sure you check your headlamp fuse and see if a previous owner installed a circuit breaker in that slot instead of a fuse. That would account for the lights coming back on after the circuit cools off.

Tractor Dan · Apr 10, 2013

Thanks for the input. The headlight switch isn't actually too horrible for me to get to. I have done it before and seemed i had more trouble from it being 100 degrees outside and roasting in the truck then i did with getting to the switch. I'll double check those fuses and see. Never thought about it being that the previous owner done that. With the guy i got the truck from anything is possible. It was scary he was even allowed to drive.

Tractor Dan · Apr 11, 2013

Ok. So dug into her this morning. From what i found nothing appears to be outwardly wrong from the looks. Checked all fuses for the cab fuse box and they are all in good shape and proper amp rating. Wiring looks good from what i can tell without getting all the way back into the dash board. No cracks,burns,or anything of that nature. However i did find that the two mounting screws that hold the headlight switch in place the molded plastic shaft they screwed into snapped off. So i'm kind of considering maybe fixing that somehow either with screws or trying to super glue or jb weld the plastic stud back to the dash panel. I will replace the switch if needed obviously but i figure try a cheap fix for the loose switch since it's not secured to the dash panel and see if it's the source of the problem. I know from fixing skidloaders it's amazing what a wee bit of vibration or jostling can do to electrical. Atleast on the older stuff that has been abused. Here are some pictures of the switch and wiring then the big maxi fuse under the hood. I'm also gonna for the hell of it replace the connectors on my battery cables. I have some cheaper flimsy ones now and figure replacing those with some good ones can't hurt and go over the wires while i'm at it.

http://www.mediafire.com/?cf4622ttpzc53p0,3zjaj555bdqn3mo,0071t1j774g38f8,hoy7jlzx8oxzs2c

v8nick · Apr 11, 2013

I guarantee it's the switch. It's a common problem on Fords. I have gone through 4 or 5 switches in the last few years on my Ranger. The best solution for this problem is to build yourself a new wiring harness using some relays and 14 gauge or heavier wiring and feed the headlights from the battery.

Tractor Dan · Apr 11, 2013

Well i think for now i'm just gonna go with the replacing the switch rather then rewire things method. Between running around to physical therapy and people in the hospital i don't have time to wire stuff up. So i'll replace the switch and figure out a secure way to keep it mounted to the dash panel. On the plus side it appears autozone has the switch for $30 with a limited lifetime warranty. I know that isn't a 100% surefire thing to rely on but generally they never give me any issue when i have to get a part replaced under warranty. So probably will just go that route. Thanks for the input and hopefully this will be solved. I'm still gonna go over all the wires again under the hood for cracks or anything and the wires to the lights. Just to make sure i cover all bases. That is if the rain stops. Almost 3 inches in 36 hours. :annoyed:

james hedman · Oct 15, 2013

had same problem, it was the connector for the low beams, one terminal had sunk into the plastic a bit and would not make good contact if at all. heated the metal up with a soldering iron and hammered it back into place, as gently as hammering can get. the contacts are in in a % shape one for low beams, one for high beams think of it as an upside down %. scrape the copper clean and put it all back together. so far so good. if it fails again i can just redo it. i am talking of the switch on the steering console

Losing low beams on headlights

Tractor Dan

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Earl43P

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Tractor Dan

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