Just replaced headlights and high beams on my 72 cutlass. When i turn my head lights on only the one right lights up, but as soon as i push the high beams all 4 turn on. Why is only one light going on when all 4 work?

 

The high beams are a different filament inside the outboard lights...when the low beams are on there is a problem with either a bad connection or the light is no good...check connections and grounds for that light...

 

Yellow hit the nail on the head. Just went through this with my delta. Cleaned the ground, all terminals, still same problem. One of the filaments was bad, on a new bulb. Changed it out, problem solved.

 

However if the high filiment in that bulb is working, then the ground is good as it is shared with both filaments.

 

Assuming all four lamps are OK, I'd just go ahead and change the dimmer switch. All the wiring for the headlights goes through it. It's $10 at the local parts store, easy to swap, and the cause of about 95% of all headlight switching weirdness.

 

Sorry, Jaunty, but he has one low beam turning on, so his headlight switch is working fine. No point having him change out perfectly good parts.

805, clean the positive low beam connection on the bad light.
Use a very small screwdriver to depress the little tab that holds the brass terminal inside the connector and pull it out through the back so you can get at it.

Once there, you MAW take out each terminal in turn, wire-wheel it, very gently crimp it just the slightest bit tighter, coat it with Vaseline, and replace it in the connector.

- Eric

 

I didn't say change his headlight switch, I said change his DIMMER switch. You know, the one on the floor!

 

Right, but still the dimmer is doing its job since it is switching between low and high.
Now if BOTH low beams were out, the dimmer could be suspect...

 

Well, I TYPED "dimmer," but somehow it came out "headlight."

Honest, I was thinking "dimmer" so hard, I didn't even see that I had typed the wrong thing when I re-read my post .

However, it doesn't matter, as Rob already said, the same thing applies to both switches - it's not either one of them.

I'm going to have to hire an editor to read my posts...

- Eric

 

None of this is necessarily true. I agree that the cause most likely is something else, but just because the dimmer appears to be working correctly doesn't eliminate it from consideration as long as the headlights are still not working properly.

As I said, the dimmer switch is a simple, cheap fix, and on a 40-year-old car, if it's the original one, changing it would probably be a good thing to do, anyway.


From the OP's description, the first thing I would look for is bad connections at the headlights assuming all four are known to be in good working order. If all that checks out and the lights still don't switch between high and low beam properly, I'd look next at the dimmer switch.

I notice we haven't heard back from the OP since his initial post. It would be useful to know what his additional troubleshooting has turned up.

 

Sorry, Jaunty, I don't mean to be argumentative, but I must take issue with what you said.

In this case (as we know it), it does.
One high-beam wire and one low-beam wire run from the high-beam switch to the left hand high-beam and low-beam terminals (respectively), and then to the right high-beam and low-beam terminals.
Therefore, since his right low-beam is working properly, we can be certain that

1. the high-beam switch is working, and
2. both wires from the high-beam switch to the headlight terminals are working, and have good continuity all the way through.

This sounds good in theory, but if you compare build quality of original GM parts with that of new aftermarket foreign-made parts, you're probably better off keeping the old one, as a new one may be poorly made and subject to failure long before the next forty years have passed.

- Eric

 

X2 to all.
I am also willing to trust the function of a 40 year old factory part to a new offshore one. I have had many bad experienced with the latters.

 

I'm not. "Offshore" doesn't automatically equal bad.

These switches are very simple mechanically and are cheap and easy to replace. If there's any chance that the old one is suspect, it's well worth making the change.

 

sorry for the late reply but thanks for all the comments. It seems you guys were right and it ended up being the faulty dimmer switch. before i switched it out my lights started flipping out, flashing on and off or not even working. pretty cheap and easy fix...I went ahead and put in a new headlight switch....which ended up being an hour and a half job itself! getting to it was a pain in the a

 

Careful who you're giving credit to here! *I* was the one who suggested the dimmer switch while these other bozos were all over my case telling me how wrong I was and about not putting "offshore" parts in their car.




which is why you change the dimmer switch FIRST and see if that doesn't fix your problem. Doing so is a snap compared to dealing with the headlight switch.

 

Bozo or not , the problem 805Cutlass described:
CAN NOT have been caused by a bad high beam switch. Period.

Either he described the problem inaccurately, or he nudged something else while working on it and fixed it without realizing it.

If anybody can tell me how a bad high beam switch can send half of the electrons to one headlight and half of the electrons AWAY from the other headlight, through the same single wire, I'm all ears.

- Eric

 

Yeah, yeah, yeah. Give it up.

I learned long ago that one does not question the dimmer switch. One just bows to its wisdom.

 

Lol

 

Sorry, but Eric is completely correct on this one. There is only ONE high beam wire and ONE low beam wire coming out of the dimmer switch. It is NOT physically possible for the dimmer to cause a problem with only one light. Either all work or none work. The single low beam wire runs from the dimmer through the firewall connector to the LH low beam connector, where a second wire comes out of the connector and runs across the core support to the RH low beam. Same goes for the single high beam wire out of the dimmer, except it also splits to go to each of the four high beam terminals in the connectors.

The ONLY possible causes of this problem are a bad filament in one bulb, a bad or loose splice in the terminal where the wire to the RH lamp splits off of the LH one, a bad or loose terminal in the connector for the non-functioning bulb, or an internal break in one of the wires. That's it, period. It CANNOT be the dimmer.

 

Give it up, Joe.

 

By the way, it's very important to remember one thing. He never said that the dimmer switch was the problem. He only said that replacing the dimmer switch fixed the problem.

There is a difference.

 

My point exactly.

Although usually with me, it's the reverse - I fix one thing, and something completely unrelated STOPS working.

- Eric

 

Fair enough, however being a cheap b@st@rd, I really don't like to spend money replacing perfectly good parts, which is what the OP did in this case. I also don't like to see bad information get disseminated, which is also the case here.

Fighting truth decay since 2007...

 

Now now, Joe, you're jumping to some unsupported conclusions here. You have no idea whether or not the dimmer switch was a perfectly good part. None of us really knows what the real problem was. The fact that replacing the dimmer switch DID fix it says something, and what it says is that it was most likely the problem, no matter how much you and MDchanic want to keep tilting at windmills.

 

I will PayPal $100 to the first person who can demonstrate to me how it is physically possible for the dimmer switch to cause one headlight not to work.

 

Joe, Joe, Joe, you disappoint me. No one more than you should know that some days you're the bug and other days the you're the windshield. You're a car guy! You should know all about windshields and probably more than most of us about bugs. Today it just so happens you were the bug.

 

In support of the laws of physics, I will chip in another $50 to anyone who can realistically show that this is possible (no flux capacitors or warp drive).

Specifically, I will PayPal $50 to anyone who can show that it is possible that the headlight dimmer switch can cause one headlight to go on, while its opposite (functional) light stays off (either high or low beam) in a car with an unmodified headlight system.

This is absurd.

- Eric

 

Actually, what's absurd is you guys offering "$XXX" to anyone for anything.

 

Long ago someone killed a chicken, and his sick child recovered. He went on to become a witch doctor.

 

Killing chickens makes more sense.



- Eric

 

I was going to suggest that people would have an easier time of collecting Chris Witt's standing $1M (or is it $2M now Chris?) reward for proof of the existence of a SMW 403...

 

Looks like i spoke to soon. i came back from work today and tried turning my lights on and now none of them want to turn on. Looks like your gonna hear alot of "told ya so's"

I thought buying a cheap 8 dollar switch would be an easy fix
but looks like its bigger than that. My blinkers arent flashing and dash lights dont seem to work either.Im not very knowledgeable when it comes to wiring and stuff like so when i replaced one or both of the switches i might have bumped and temp. fixed my prob like Eric said.

From what i can see the wires look ok and im thinking it may have to do with the connections on the back of the fuse box. Ill take a closer look at it tonight and let you guys know. how do you take out a fuse box out to check the connections in the back?

 

So tell me, how much did these guys pay you to change your story?


Nothing related to headlight wiring passes through the fuse box. The headlight switch has, I believe, its own circuit breaker. If your headlights don't work AND your blinkers don't work AND your dashboard lights don't work, you have all sorts of issues going on, and they're not necessarily related.

 

hahaha.... i was laughing reading the next couple post cause it really seem all against one.
but damn this sucks man, i really gotta take a closer look...it seems the person who owned the car before me tried doing all kinds of things to it, like taking out the key holes on the doors and installing auto lock doors, and really jacked me up.
not looking forward for whats to come

 

An old car owner's greatest enemy is the person who owned it just before he did. When I first got my '67 Delta, the tailights would stay on whenever the ignition was on, even if the headlight switch was off. It turned out to be some bollixed-up wiring having to do with the under-hood light, which you would think would be relatively totally unrelated, and I only fixed it by accident one day when I was trying to do something else.

 

$49.99 .

 

Man, he's a cheap date! Padavano was offering $100.


I'll offer him $59.99 to change it back!

 

805 im like 5 miles away if you ever need any help, i think theres a slim chance that between the two of us we MIGHT and i mean might be able to figure something out. HAHA Im no master but i did just rewire my cutlass and my lights were acting weird as well. Bad grounds.

6617132597 text anytime bro
I tried to pm you but it wont let me. Idk
Hope you get it.

 

You are correct. Self-resettable circuit breaker in the headlight switch. Switch power comes from a feed directly off the horn relay post under the hood. This is where Kurt is supposed to jump in and tell you that you can download the wiring diagram from Wild About Cars...

Didn't cost a cent. I just had Uncle Guido pay a visit.

 

I've been reading this thread and the above comment about wiring diagrams from wild about cars caught my eye. Do you have the url for this website ??
I don't have any info on the wiring in my 84 cutlass supreme. I just changed the "washer lever" on my car and now it's doing strange things.
All functions work properly " except" the wipers won't turn off.
Any comments or info on the website for the diagrams ??
thanks
wizard