Headlights stuck on highbeam

[Brokeass Boater]

My lights are stuck on high, had to drive 30 miles home last night pissing off a lot of folks. I replaced the MFS a few weeks ago because of the fog lamp knob not working and since all has been golden. The MFS seems to be indexing mechanically toggling the light switch. Is there a relay, voltage, that should be checked? Hope its not the MFS already, Dang it, Crab season starts next week and I still need to get the motor back in my boat this week and run thru all the crab gear. Sure didn't need another little project right now, O'well sleep is over rated right?,,,gregg

 

[Fouledplugs]

without any troubleshooting, I would start at the MFS. They are known to have problems. Some folks have been able to crack into them and fix them internally. Might be worth a try.

 

[Jerry Bransford]

My lights are stuck on high, had to drive 30 miles home last night pissing off a lot of folks. I replaced the MFS a few weeks ago because of the fog lamp knob not working and since all has been golden. The MFS seems to be indexing mechanically toggling the light switch. Is there a relay, voltage, that should be checked? Hope its not the MFS already, Dang it, Crab season starts next week and I still need to get the motor back in my boat this week and run thru all the crab gear. Sure didn't need another little project right now, O'well sleep is over rated right?,,,gregg

That's a simple circuit without a relay, the problem is almost assuredly inside the MFS. If you replaced the OEM switch with a store-brand switch that's not a good thing to do as store brands are the cheapest of the cheap. Try to find an OEM/Mopar, and don't be mislead into thinking an "OEM Replacement" means Mopar, it doesn't... it just means it fits where the original part came from.

 

[Brokeass Boater]

OK thanks guys, I read in the service manual that's posted as a sticky a simple check with a ohm meter should prove or eliminate the MFS. No plans to tackle it soon, Crab season is right around the corner and I'm way behind getting ready,,,gregg

 

[Brokeass Boater]

Update, I finally took a look at the high beam problem. I ordered a second MFS, this time a OE for 150.00, installed it and the same issue. I don't know how this switch actually works, seems like there must be a internal relay base on how the headlight selector standard, post? is nothing more then a momentary switch and would need to complete a circuit to hold the relay contacts in when switching between low and high beam. So with that theory I pulled the plugs at each headlamp and gave them a good spray with contact cleaner and cleaned the sockets best I could. Good news is that is all it was, dirty plugs at the headlamps not making a good contact on the low beam circuit. Happy to have it fixed, but sure hated to throw down a 150 bucks right before Christmas on something like this. I have the new/old MFS boxed for a critical spare now. Merry Christmas guys,,,gregg

 

[Chris]

Update, I finally took a look at the high beam problem. I ordered a second MFS, this time a OE for 150.00, installed it and the same issue. I don't know how this switch actually works, seems like there must be a internal relay base on how the headlight selector standard, post? is nothing more then a momentary switch and would need to complete a circuit to hold the relay contacts in when switching between low and high beam. So with that theory I pulled the plugs at each headlamp and gave them a good spray with contact cleaner and cleaned the sockets best I could. Good news is that is all it was, dirty plugs at the headlamps not making a good contact on the low beam circuit. Happy to have it fixed, but sure hated to throw down a 150 bucks right before Christmas on something like this. I have the new/old MFS boxed for a critical spare now. Merry Christmas guys,,,gregg

Occam's Razor strikes again! "The simplest solution is most likely the right one."

I can't tell you how many times that's proven to be true. Glad you got it figured out, thanks for the update, and Merry Christmas to you too!