39 Hudson Six Headlight issue, please advise

Val

I put a dual headlight relay in my 39. But only the driver side light seems to be brighter. Relay was bench checked and works as advertised. I removed teh chrome trim and Glass Lense from the passenger side to check that my reflector is set in correct and grounded. It seems to be. The wire on the back that goes into the socket are in very good shape. SI checked at the terminal strip where the wires connect under the hood and those are tight and in very good condition.  I'm not sure where to check or what to do. I will do a voltage check to see if I am indeed getting a full 6 volts there but other than that I'm lost. Could it be the bulb?   

29sptphaeton

Check the ground for that hedlight.

Jon B

I agree with "29" -- check the ground.  A quick way would be to run a wire between the socket body and the + (ground) terminal on the battery, when the headlight switch is on.  When you do so, do you notice any brightening of the passenger side bulb?

If so, don't depend upon the socket's having a good ground through the headlight reflector, attachment clips, shell, attaching bolt, grille shell and frame, to the battery.  Somewhere in that chain there must be a bad connection.  Instead, solder a wire to the body of the socket and run the other end to a good ground (like a screw passing into the frame).

Of course, the problem could also be in the contacts on the headlight socket itself.  Check them for corrosion or a bad connection.

Val

Thanks Ed and Jon B! I will do that. Trhe light does come on but doesn't get brighter. So I'll do that check and if it it works out I will wire as you said and make a.better ground. 

Val

Ok so ground wire from battery to light socket made no difference. Also now my driver side light is intermittent. Gotta wonder if that relay is good? I don't hear it click when I turn the lights on. At least not every time. Gonna check if indeed it is closing and volts from it. 

Jon B

A problem with the relay would not explain why one light is brighter than the other.  Any intermittency caused by the relay, would occur in both lamps. Since you said there wasn't a grounding problem, try running a wire from one socket terminal to the other socket terminal. 

Logic tells us that both lights should now illuminate with the same brilliance, since the jumper wire has now equalized them.   If they're both equally bright, the problem must lie in the connection from the passenger-side socket to the relay -- if not in the wire itself, then in the connection to the socket or relay terminal. 

However, if the passenger side bulb's still dimmer than the driver's side, try switching the bulbs.  Is the driver's side bulb now the dimmer one?  Then, that bulb is possibly damaged -- or rated at a lower wattage than the  other bulb.   (Are both the bulbs of the identical type?)  If the passenger bulb's still the dimmer one after the exchange, investigate the socket for some internal flaw.

Val

Hey Jon B, I haven't messed with for a couple days, but I will try as you suggest this afternoon. Keep you posted as this is baffling. 

Val

Oh my God!!!! I should have just left my headlights alone!! Having to make slight modifications to the wiring in the car I did get them both working but only on low beam. When I push the dimmer switch they go out and high beams don't come on. I did a voltage check at the relay on the switch side. Shows only 4 volts. But 6 volts 9n the lights side. ???? Maybe a bad dimmer switch? Although it worked fine before. Only thing different is the relay. Last night they went out completely but if I tap the coils on the relay they come. Both high and low beam depending on which side I tap. And they will stay on. But not by operation of the switch on the dashboard. Again I wonder about the dimmer switch but honestly I'm lost and fed up! Any ideas? Anyone????

Toddh

Firstly just know I’m firmly in the ‘original is best’ camp.  If you have good wiring in the proper gauge for your voltage, good mechanical grounds and the switch contacts are clean and making good contact, there’s no benefit to adding a headlight relay, in my humble opinion.  You’re simply adding another point of failure in the system.  

That said, my suggestion is to remove the headlight and dimmer switches and clean them thoroughly with electronic contact cleaner. Check and clean any terminal screw contacts.  As others pointed out you must have an excellent ground.  On my 46 headlight buckets, it’s a screw terminal and relies on the bucket mounting screws to the fender for ground.  Disassemble the headlight relay you just installed (usually there are bendable tabs holding the protective ‘can’) and clean the contacts. The issue you’re seeing sounds like dirty contacts on the headlight relay to me. 

The proper gauge of wiring is important for 6V.  The factory used 12ga to feed the light switch and then the dimmer switch and used 12 ga out to the headlight terminal block (this is on my 46 but the concept is the same). From the terminal block to the headlight buckets, it’s 14ga.  

You can get proper cloth covered wiring at several places or you can just use modern (stranded!) wire. Just use the proper gauge. 

Val

I feel ya Toddh, I'm traditionally a purest myself with these cars but I just wanted brighter lights for night time driving. But I will check the contact points at the switches. The wiring in my car was replaced with a new wire harness in 2017 by Doug wildrick. I believe it to be a 10 gauge wire. And that's the gauge I use with a slight modifications that I made. 

Val

And every thing worked as advertised before I put that relay in. So I can agree that it's just another point of failure added. 

Toddh

10ga is overkill but the bigger the pipe, the more the current will flow.  Also forgot to mention that I crimp and solder all terminal connectors and I use ‘star’ washers on any chassis/body ground connections.  

Good luck, Val!

Toddh

Oh yes. One more thing to check.  Are you using sealed beans or lamps?

If sealed beams, check the connections on the headlamp plug.  They can be removed and cleaned too

Val

No sealed beams. Original 2331 bulbs.

Toddh

In that case; have you polished your reflectors to a mirror shine?  Have you cleaned the bulb sockets and lamp element terminals?  It’s possible you may have a ‘cold’ solder joint (read: resistive) and it wouldn’t hurt to reheat sufficiently with a soldering iron.  

For polishing the reflector, do not use a paste or overly aggressive polish.  I use dry fine lamp black and a velvet cotton cloth.  Polish in one direction and then perpendicular.    Happy to help if you need sources for each.  

eddiehudson

1. Make sure you installed a 6v dual headlight relay, not a single or 12v one.
2. If it is correct then remove the relay from the circuit and see if your system restores.
3. If it doesn't, troubleshoot your wiring.

Jon B

Let's stop for a moment and verify how the relays are wired in.

In my car, the main headlight switch runs to the dimmer switch.

From the dimmer switch, two wires run to the relay: the high beam and the low beam.

From the relay, one wire each from the low beam and high beam outputs, to the corresponding hi / lo terminals on each of the headlight sockets.

And, I'd advise a ground wire soldered to the body of each headlight socket, and running to a good connection in the frame.

Yes, dimmer switches -- even NOS ones that have sat on the shelf for years -- can go bad.  I myself have encountered several that have problems.  It's been explained to me that -- if the switch is really OLD "new-old-stock", the grease within it has solidified, and things don't snap into place as they should.  Some switches can be dis-assembled for cleaning and re-greasing.  (I think some are merely held together by bent metal tabs; these can be pried apart to release both halves of the switch.  Then the tabs can be re-bent to close up the switch when re-greased.

It's my theory that you could use a "modern" (12-volt) dimmer  switch because the amount of amperage you're sending through the switch is miniscule.  It's only tripping the relay, not powering the headlights.  And, a brand new 2020's dimmer switch is bound to have good grease!  Anyway, that's my theory and I'm stickin' to it....

Val

I want to thank you all for your comments here and advice. I am beginning to wonder if the relay isn't a 12-volt relay. As it was tested with a 12 volt power source and worked GREAT! I have reached out to Doug Wildrick and await his reply.  

Val

I tested the relay this morning by putting a jumper wire on the battery and the switch side of the relay. It works as advertised. So it's a 6 volt relay. Today after work I checked ground by putting the jumper wire on the base of the relay and the battery ground. Still no bright headlights. Dim yes bright no. So I guess it has to be one of my two switches. Headlight at the dash or dimmer switch. Unless maybe it's a connection issue. I have to take the radio out to check the dash switch. 

Val

Are the switches hard to come by? 

Geoff

Have you checked the voltage at the output side of the relay, where the wire to the bad headlamp connects?  You should have full 6 volts here, and at the headlamp itself.  You ore over-thinking the issues.  There is no way the headlamp switch itself could affect the  voltage, except to the relay coil.  
The headlamp switch makes the coil points transfer, connecting battery voltage to the output.

eddiehudson

The relay should be marked 6v or 12v on the base or on the bottom. A dual relay should have 2 terminals in and 2 terminals out. Singles should have 1 terminal in and 1 out. If yours has some sort of part number and brand name, I might be able to ID it.

Val

Thanks Geoff, eddiehudson and all who have replied. I explained everything to Dr Doug and he told me today to scrap the relay. He will send me an NOS one. He says that one must have an issue inside somewhere as my switches are good and he would know as he wired my car. So I wait for one to arrive and swap it out. I have a dual relay 2 terminals in and out and one for battery. When I get off I will check for markings on the bottom. I had 3.5 to 4 volts on the input (switch) side of the relay and 5 on the output (lights) side.   

Geoff

5 volts is not going to give you any sort of decent lighting.  What sort of voltage do you have at the battery?

Val

6 static and 7.4 running

Geoff

So 5 volts at the output of the relay indicates voltage drop across the rely contacts.

Val

Yes, thats what Doug said too and he is sending me another one. He said it could have been bad 70 years ago and someone just put it back in the box.