Low Beams dead, Hi Beam Fine?

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gdizzle

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Driving the 66 Dart again, after putting about 10 miles on it all of last year. Go to turn on the headlights and nothing, but I hit the hi beam switch and high beams light up fine.

So can anyone remind me, is there a separate fuse for the low beams?

Also note, I do have the headlights installed on 2 relays. I tired tapping on the relays but nothing changed.

Any help? I do have spare headlights, but hate to fart with removing the bezels if I dont have to.
 
Simple. Only thing "common" is the dimmer switch and the path of the low beam power wire..........From dimmer switch and connector, through bulkhead connector, one wire around headlight harness, splits and feeds both headlights.

OR the rare possibility that you blew out both headlights. "I spose" it has happened

Or a problem with your relay ........Where do they get their power? I don't know........"you" wired them
 
Floor Switch is bad. Headlight switch in the dash in regards to the headlights themselves only provides switched on power to the floor switch. Floor switch has 3 wires.

1 Power in from the headlight switch in the dash.
2 low beam out to lights
3 high beam out to lights

You have power from the dash switch because your high beams work. Your low beams dont work probably because the floor switch is bad, or the low beam wire on the switch is corroded. Being that the headlight dimmer is on the floor like that, there is usually a lot of dirt and water that gets into that connection.

If you had a bad ground from the headlights themselves to the car body, neither the high or low would work.
 
Yes I just tried a few things.... Replaced the light - same issue. Then swapped the relays, ... same issue. So relays are good, lights are good. Next will be that switch on the floor. Maybe just came loose or corroded. I did have that issue when I first got the car... that floor switch had completely fallen apart. Of course what I do in the meantime is just drive around with the hi beams on even those high beams are nothing like the modern low beams on newer cars. no one ever flashes me. good ideas guys. thanks
 
Geez man learn to troubleshoot and stop wasting time parts and money "throwing them" at a problem. Buy yourself a test lamp, a cheap multimeter, and get/ make some alligator clip jumper leads, and go over to MyMopar and download yourself a free service manual

WHY AM I SUCH AN *****LE about this? Simple. In my younger days I had to BUY a service manual if I wanted one. There WERE NO easily obtainable cheap RUGGED multimeters. They were analog meters, and if you wanted a small cheap one you had to order them from an electronics supply house. This was before RadioSh*t, and hardware and parts stores carried and sold them.

SIMPLE

Get a test lamp

Access dimmer switch. Turn on headlights and look at the cluster, and cycle dimmer so that high beams are OFF. Now probe the dimmer switch. There are three terminals, and with light switch "on" there should be power on 2 of them. One is power TO the switch from the headlight switch. One is power TO the high beams, and the 3rd is power TO the low beams

If you have power there, look up in the diagram/ manual, and find the low beam power feeding through the bulkhead connector. Don't have it? Simple. It's right there in the bulkhead connector

Try wiggling the connector, watch the lights. They come on? Flash or flicker? You have found it.
 
Then swapped the relays
What relays?
There are no relays unless you have installed them.
If you installed relays then depending on your system design, there ought to be eitehr one or two fuses or circuit breakers.
 
Awesome guys. Yes, one of the first things I did when I got this Dart was to install relays on the headlights, I was told (by this forum) that this would give brighter lights.
So I did yank the carpet back, removed the switch, hooked it up to my old multimeter and tested continuity on the switch...all fine.
Then tested for volts on the plug.... all good.
Then hooked it back up and now it works. There was no corrosion or rust. Actually the switch looks really good, it is about 6 years old.
So there you have it. Low beams are back and ready to take on the night. Thanks for the help.
 
Guess what, I got the same problem again. High beams good, low beams dead. I removed the floor switch, tested it and it has continuity. Can the switch be bad yet still show continuity? I do not have lo beam power at the lo beam relay (there are 2 relays, one for hi one for low.) So it has to be that floor switch or the wire leaving the floor switch.
 
I like to check grounds. It wouldn't be a first to be screwed by a bad ground. Usually is the ground or the switch, but I have much to learn.

$0.02
 
You can make sure the dimmer switch is working by pulling the connector back far enough to get your test light or voltage meter leads on the the blades coming out of the switch. The center will be hot as soon as you pull the headlight switch out. One of the side blades should also have 12 volts. Press the switch and now the other side should have 12 volts.
 
If you can back probe dimmer switch connector and bulkhead connector (engine side) do so with everything hooked up. I found when I worked that hooking up a headlight or spotlight bulb to check wiring under load woeks better than an ohm meter without a load.
 
This is a simple problem. It is either the dimmer switch is bad, or it is the low beam wire leaving the dimmer, going out through the bulkhead connector, (or the terminals in the bulkhead connector) and into the harness leading out to the lamps, or the connection on the terminal at the left side lamps, PERIOD.
 
Learn to think of wiring diagrams as a MAP. When you look at a map, and there is road construction or the bridge is out or the road otherwise closed, "flow" down that road must stop. Same thing with wiring.
 
THINK how it WORKS. THINK of the path the map the flow

Turn on the LIGHT SWITCH where does it go?

To the DIMMER SWITCH.

DIMMER switch provides EITHER dim or bright. Do dimmer switches go bad? Do the connector terminals go bad? YES!!

ONE wire for Each from the dimmer, HOW do they "get there?"

BOTH bright and dim wires go OUT through the BULKHEAD CONNECTOR. Are bulkhead connectors a problem? YES!!!

THEN where? The harness wires carries the bright OR dim power through the harness wires, around the fender, out to the radiator area, where it all junctions to the two lamp connectors. CAN THAT BE A PROBLEM? YES!!! More TERMINAL CONNECTIONS!!!!

Can BOTH headlights be burned out? NOT likely but POSSIBLY. Are headlights a problem? YES!!
 
"has to be that floor switch or the wire leaving the floor switch." not necessarily, it could be the bulkhead connector where the wire passes through the firewall into the engine compartment.
That would be where I start IF you are getting 12 volts out of both hi & lo output side of Beam Selector Switch, AND yet not getting 12 volts to the lo beam relay.

"I do not have lo beam power at the lo beam relay" by this, do you mean you are not getting 12v. at the trigger side of the relay-(relay terminal 86) check your hi/lo switch and bulkhead connections.
OR
Do you mean, No power at the side of the relay where power comes from the battery -(Terminal 30). Are these relays fused independently from the battery, (if so, check the low beam fuse) OR do they share 1 fuse? if they share, then fuse is not the problem because the highs work.

Terminal 85 should go to a good ground
Terminal 87 is the LOAD -(your headlights)
 
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Welpp... glad I don't have to come here for diag help...:lol:
The reasons I rarely post here anymore, qualified advice not taken, argued with, extra advice thrown in un-qualified or qualified w/o reading the entire thread or even the entire original post, same exact question posted as a previous post just days before...We enjoy helping, but I quit doing work for folks in My own life that simply wanted the "Daddy Fix Daddy Tell Me!!" solution to their ambitions & goals, with little to no effort or intention of learning/doing it themselves.
NOT really directed at the OP here, just why Del may be a bit testy,....lol!!!!
 
The reasons I rarely post here anymore, qualified advice not taken, argued with, extra advice thrown in un-qualified or qualified w/o reading the entire thread or even the entire original post, same exact question posted as a previous post just days before...We enjoy helping, but I quit doing work for folks in My own life that simply wanted the "Daddy Fix Daddy Tell Me!!"
Pretty much the same here.

just why Del may be a bit testy,....lol!!!!
I think in this case its pretty clear.
67Dart273 took the time to explain in detail why the problem must be downstream of the headlight switch, and how such problems can be narrowed down so readers of this thread can figure these problems out themselves.
Dartswinger70 then posts a WAG that its the headlight switch.
I might have been a little less testy and ignored it or maybe done this
shake_head-gif.gif

My point is I agree, not a surprising reaction. LOL
 
The reasons I rarely post here anymore, qualified advice not taken, argued with, extra advice thrown in un-qualified or qualified w/o reading the entire thread or even the entire original post, same exact question posted as a previous post just days before...We enjoy helping, but I quit doing work for folks in My own life that simply wanted the "Daddy Fix Daddy Tell Me!!" solution to their ambitions & goals, with little to no effort or intention of learning/doing it themselves.
NOT really directed at the OP here, just why Del may be a bit testy,....lol!!!!
Pretty much the same here.


I think in this case its pretty clear.
67Dart273 took the time to explain in detail why the problem must be downstream of the headlight switch, and how such problems can be narrowed down so readers of this thread can figure these problems out themselves.
Dartswinger70 then posts a WAG that its the headlight switch.
I might have been a little less testy and ignored it or maybe done this
View attachment 1716021456
My point is I agree, not a surprising reaction. LOL
Well man its like this... not everyone looks at wiring diagrams in the real world most are wanting a quick place to look and honestly a suggestion of a part to throw at it who really knows how to trouble shoot? as for myself I am a retired ASE master tech and also was TRAINED in Fighter jet avionics by the Air force. I served in Iraq 15 years ago so it is all fresh in my memory and basically electronics ,once you know it it doesn't change. The last thing ill do is argue in here... I will stand up for myself and have. But, my car runs and my headlights work. Now in real life my experience has been that the headlight switches burn up. I once drove a 71 Pontiac home with my hands under the dash holding the wires to where the lights stay on. That same switch is the same type used in Mopars and just about everything else. BUT I digress, no one wants to offer an opinion to be jumped on and attacked buy some anonymous internet poster / troll hunter/ a person who is cranky by nature didn't take their meds etc. Also there are young guys running these cars that need help. They are the ones here I would imagine that really don't need to be attacked. But yes the place (these forums) has changed I suppose people in general are fed up all around. My advice to anyone is get a Chilton manual or go to Allpar do the research learn how to read the wiring diagrams know what power ground is and which side of the circuit is switched know ohms law. Alot of times you can wiggle wires and see something happen that's called a wiggle test etc. generally if something doesn't work check fuses first start easy then work your way up to shooting wires. I see alot of folks starting with the hard stuff first it shouldnt be that way.
 
my 2 cents and likely already covered by others in here. With the car in the no low condition

Everything plugged in. Probe the output wire from dimmer switch for low beam, some are violet in color. Hot? Yes.
Do the same thing at the engine side of bulkhead where that wire passes through. Hot? Check from the compartment side too.
Probe the oem headlight plug, hot.
Pull relay from block or plug and probe the trigger terminal for heat. Check that the trigger/ground terminals are not pushed out of the block/connector.

Four simple test light things to do that will narrow down where the issue lies.

Check feed into relay power side 30 terminal as well. Is it fused? (Don't think it is this as it is intermittent)

You know it isn't the switch because the high beam works and is fed with the same wire into the dimmer.

Could be dimmer, crappy/intermittent bulkhead connection, bad engine compartment wiring.
 
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Hey thanks for all the excellent troubleshooting ideas. This is a car that I picked up to try to interest my son in a father son project. He has now left and joined the US Marines so I am on my own trying to futz around with the Dart. I was hoping that it was not the bulkhead, because that thing is a gaggle of wires, all spray painted black (unknown why). I know a few of those terminals are melty looking , but that is a real old melt. A few years ago I did replace a couple of those Z terminal conectors, but tried to not mess with most of them. I wiggled them around and now the low beams work!!!! I have a bottle of DeOxit, I am thinking of spraying all the bulkhead bits. Might that help?? I do appreciate being taken to task by the elder members of this forum. Unfortunately I am a drummer by trade, which puts my IQ at a pretty low number.
 
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