Turn Signal Pilot Light

pseftoncomcastnet

Some problems are so simple that they seem almost impossible to solve...

The turn signal pilot light on my 51 Commodore is one .I have the OEM switch with a 3 prong 6 volt flasher and a positive ground electrical system All wiring is new. My situation is that the front and back signal lights flash appropriately, if more rapidly than on a modern car.

The pilot lamp will not light or flash. I have substituted several known-to-be-good flashers and bulbs, with no change.

I pulled the bulb socket and wiring out from behind the dash and rigged a ground to the frame with alligator clips. Still nothing.

With the VOM, I read a pulsating current of up to 5+ volts between the socket and ground. I also read 0 OHMs resistance between the socket and a splice  where the wire goes into the turn signal base. The bulb illuminates when current is supplied to the splice with a jumper.

My theory is that, while there is voltage and continuity, the bulb is not receiving enough current to illuminate the filament. The culprit could be a wire connection that has only a few strands connected or a corroded contact, both within the plastic flasher socket. My questions are whether this sounds plausible and whether there is any way to open the plastic socket.or at least clean the contact.

Peter S.  

 .  

Geoff

Peter, your terminology is slightly wonky, you cannot supply "current", only voltage.  When a voltage is applied to a resistance, a current  results.  The most likely cause of your problem is bad contacts in the turn signal, if the wire from the flasher unit goes to the switch.     Try connecting the "P" terminal of the flasher itself to the pilot light wire and see if that works.   Good luck,

Geoff    

pseftoncomcastnet

Glad my thoughts came across despite my garbled words....

In case anyone has been wondering about the innards of a flasher base, I've attached the images below. The thing falls neatly in half if you drill out the center rivet, and I suspect it can be reassembled. It's more highly engineered than I expected. The prongs on the flasher fit into the slots in the sides of the metal cylinders.

But ,alas, the mystery continues. I found that the cylinders were quite clean and even after I polished them up, the bulb stayed dark.

The situation remains - I have voltage that fluctuates between 0 and 5+ volts at the pilot light flasher prong, the button in the pilot light socket, and the socket housing with the bulb seated, but no light. I have a good ground, circuit, and bulb because the bulb lights brightly with a jumper from the ignition switch feed to the pilot light flasher prong. I have 0 ohms resistance from the flasher prong to the bulb circuit.

Mystified!  

Peter S.

Geoff

Peter,  I have not seen this type of flasher base before, usually they are a prong type like the sealed beam plugs and sockets.   Normally the pilot light connection goes directly to light itself.  Is this the case with yours?  Or does the pilot connection go to the switch?   

pseftoncomcastnet

Hi, Geoff

I fear my imprecise language may be muddying the waters. The flasher itself is a standard issue aluminum min-can with 3 prongs. My picture is a cutaway view the plastic receptacle that the flasher plugs into. Essentially the flasher prongs fit into the slots in the metal cylinders. A feed wire runs from the 6 o'clock cylinder to the back of the instrument panel and the wire to the switch runs from the 12 o'clock cylinder. The three o'clock cylinder accepts the muddle prong of the flasher and connects to a wire that runs directly to the pilot light,  

PS - Alexandria, VA USA

RichardD

Generally on the can flasher, the P terminal feeds the indicator flasher light; X is the input voltage; L is the load side { the bulbs }

Geoff

Using Richard's explanation of the terminals, both X and L terminals should have voltage on at all times with the ignition switch on, until the  indicator switch is activated, in which case the  L terminal will flash on-off-on etc, and the P terminal will flash off-on-off etc. .   In other words the P contacts are normally open, and the L contacts are normally closed.   With the switch  activated, both P and L contacts regularly transfer, one set acting opposite to the other.   What you can do is try connecting a jumper from one side of  the  indicator switch (can be either side) direct to the P wire and see if the P light illuminates.   If it does, then you know the fault is in the P circuit inside the can, or the contacts between the can and the terminals.  If it does bring it to life then there is a way to fix it using diodes.  But lets go one step at a time.

Geoff 

pseftoncomcastnet

Just ran out to the garage and tried the P to L jumper experiment. The lamp glowed like a full moon!.

In the meantime, I learned something weird online. Just about the only "affordable" 535 6 v. flasher currently on the market is the  Bussmann NO.535 5.2 Amp Thermal Flasher. The NAPA 535 unit I purchased looks to be identical to it, and I suspect it is actually a Bussmann, In the Amazon reviews of the Bussman unit, a fair number said it was junk and several specified that connecting to the P terminal would not illuminate the pilot light. (To be fair, others liked it. But do they have a pilot light??) 

I have to go out of town for a week, so further experiments must be deferred, but I'll be all ears on my return. I thought the rewire job had gone too smoothly!

Thank you both.

PS

Geoff

This not uncommon with modern flashers, they do not light the pilot on positive ground systems.   What you can do is get two 1-amp diodes and connect the cathodes (that is the end with the white band) to each output to left and right lights, and bring both ends to the pilot light.   You must use diodes, as these are electrical one-way valves, and will not feed back to the opposite side as would happen if you just jumpered the outputs to the pilot.   Good luck.

Geoff

Jon B

There are a fair number of original, NOS flashers out there.  Try Ebay, or contact some of the WTN advertisers, like Dave Kostansek.  Possibly your owners manual would give the correct flasher number, for you to go by.

pseftoncomcastnet

As luck would have it, there's a seller on ebay with a bunch of military surplus Tung Sol 535 flashers for just a buck each more than the price that NAPA sells the not fully-functional Bussman replacements for.

Another issue with the Bussman -- it is advertised as having an audible signal, which would presumably be something like the loud clicking that the OEM unit makes when the turn signal is flashing. The Bussman is just about inaudible. Commenters on Amazon noted that they couldn't hear it with the windows open.

Thanks to all for your help.

P

 

Geoff

It seems most new flashers have some sort of electronic device switching the pilot signal,  whereas the original earlier ones are bi-metal  contacts.  I just use diodes now as the old ones are hard to find.  Hope these work out for you,

Geoff

RichardD

Would be lax not to mention the need for a 3rd taillite for signaling, braking, etc. Be SAFE not SORRY.

Rear end video for safety>>   https://vimeo.com/120428548

 

ShaneStone1964

Richard, where are you sourcing your third brake light? The auto parts stores around here don't seem to carry after markets any more. Thanks! shane

53jetman

Try Google & E-Bay

RichardD

Here is the third taillight I am running. Not the cheapest by any means, but I love it; goes on with suction cups. Available in 6 volts AND 12 volts. Has signal lights incorporated. Note that the automatic 'strobe' effect in my videos is by taillight strobe modules (on eBay): not for 6 volts.

>>>>   http://www.jandlenterprise.com/products/products.htm 

ShaneStone1964

Thanks for the info, Richard. We ordered from J and L yesterday. Couldn't have been nicer or more helpful.

shane