Technical Why won't my park lights work?

'54 Customline w/12v conversion. Everything is brand new. I have 12v at the park light terminal on my H/L switch. I have 12v at one*****on terminal inside the bulb socket (the other terminal reads 0v cuz that's for the turn signal). I thought maybe the bulb wasn't' grounding in the socket so I squeezed the socket together, tighter against the bulb......no joy. I even soldered a wire to the back of the socket and grounded it......nothing. Bulb is a known good 1157 dual filament. What am I missing?

 

If you have good power and good ground, the problem has to be at the bulb or socket.
I had a tail light that the two power pins did not line up with the bulb to make good contact.
Also be sure the inside of socket and outside of bulb are not corroded.
Does the turn signal work ok?

 

I have seen sockets that take a bulb with the indexing nubs at a different place than normal. So the bulb contacts end up in-between the socket contacts.

 

Could have a iffy connection causing major voltage drop when you load that circuit. Will it light a test light?

 

By your description I doubt this is your problem but ... A '54 Ford will have power to the park light only in the park and tail light position on the switch. With the headlights on the park lights will be off.

As I said probably not your problem, but worth a mention, just in case.

 

The bulb contacts and socket contacts line up perfectly and no corrosion on the bulb or socket as both are new. Also, the turn signal works fine.

12.37v at the one socket contact and yes, it lights a test light.

No power to parks with H/L's on which is normal. H/L, tailights, turn signals, dome light and license plate light work. Just not the parking lights.

 

Instead of a test light, use a park light bulb with a couple of wires soldered to it. Start at the headlight switch, and test along the circuit. Your test light may only draw a few milliamps, and a bad connection will supply this easily, but when you start drawing more current, the voltage drop across the bad connection gets higher.

 

With the park lights on 12.37v at the park light socket contact. The other contact reads 0v. With the park lights on and turn signal activated, 11.90v at park light socket contact and a fluctuation of 3v to 10v at the turn signal contact.

 

Did you test the bulb to be sure it was good? Just because these things are new no longer means they are good. Power the pin and ground the bulb case to light it up, I'd test both pins.

Power to the pin, and a good ground should light a good bulb. You may want to ground your test light or meter to the socket housing and check the pin for power, with your tester or the test light. If you then have power between the pin and the socket housing, and the bulb tested good above, but the bulb doesn't work it has to be a socket or bulb terminal contact problem.

The new stuff they are producing these days is very questionable. The sad part is often there is only one source for the parts, and everyone has to sell the same junk.

 

The local repair shop put single element bulbs in my O/T nova and when I stepped on the brakes the park lights came on. Or maybe it was the other way around. LOL

 

You might try a 3496 bulb. By the looks they have a longer reach on the bottom for the contacts and the same locking tab pattern, better contact? It seemed popular as a upgrade on the older Chevelle/Camaro forums as well as they draw close to the same current as a 1157 but are brighter.

 

Since you have a voltmeter, a voltage drop test should determine the problem. The problem is that you need to be able to tap into the park light power lead near the bulb socket with everything connected and the bulb in place. With the park light on, you should read within 0.5 volts of battery voltage (negative voltmeter lead connected to a good ground, I recommend the battery negative post). Anything less points to a high resistance connection between the headlamp switch and the bulb. If you have within 0.5 volts of battery voltage at the power lead, move your positive voltmeter lead to the bulb socket case. You should read no more than 0.1 volts. Anything more points to a bad ground.

Based on what you have posted, I suspect you will find the source of the problem with the first half of the test. FYI, battery voltage at the socket pin with no load won't show up bad connections.

 

Just thought of this, are the sockets new or old? If old, the springs that push the contacts up may have rusted and lost a few turns on the coil spring. This would make one contact lower than the other, but still test at 12 volts when probed.

 

Are we talking the front park light it uses a single contact bulb

 

Just a couple of thoughts. Are you using a regular bulb type test light or an led, I like the old bulb type as it helps test the circuit (plus if you use it enough you can tell by how bright the bulb is if it's close to 12v).
First take the bulb out and run a ground from the battery to the jacket and then a jumper wire from the battery positive to each contact on the bottom of the bulb (both filaments should light up one at a time). Next run a jumper wire from the battery ground to the bulb jacket (the little part sticking out past the housing when the bulb is installed), if the bulb lights up then touch the bulb socket housing, if it doesn't light up then there's a problem with the connection between the two. Never trust a ground point unless you test it.

 

The park light and the turn signal use the same filament the other filament is for brake light and not used as a front light.

 

Are you testing the voltage at the socket with your test lamp or meter?
If you have the ground lead placed anywhere other then the ground in the socket you aren't testing the voltage at the socket

 

Our '54 ranch wagon had a similar problem and after fighting with it I replaced the pigtails in the sockets, that cured my problem. HRP

 

On some old cars the park lights do not come on when the headlights are on,had a 65 chevy truck like that.I wanted the park lights on at the same time,but they were made like that from the factory,was in the headlight switch.If yours is all stock,maybe thats how it is. harvey

 

OK, tried that. I soldered a wire to the back of the socket and grounded it to the back of the grille. Metered it with Pos probe to the pin and Neg to the socket....got 2.5v. Pulled the wire off the grille and grounded it to a better ground. With Pos probe on pin and Neg probe on socket case, I got 12.23v. Looks good. Then as soon as I inserted the bulb into the socket, there was a spark and I blew another 20a headllight fuse! I'm getting frustrated!

 

Disconnected the ground wire from back of the socket and just put a clamp on the socket with a wire to ground and the light works! So......the socket isn't grounding. Why wouldn't my soldered wire to the back of the socket work as a ground? I did that because the socket wouldn't fit tight in the park light housing and I had to super glue it in, thereby negating the ground.

 

If it blew the fuse then you created a short with the soldered on wire. Post a pic of the back of the socket, also you could use JB weld, shim stock or maybe tin foil around the socket to tighten it up in the housing.

 

I wish when car guys talk auto related electrical, they wouldn't use the term "ground". It's not a ground. It is a Negative that in this case is bonded to the metal of the car and uses that the complete a circuit back to the Negative of the battery. The vast majority of the time it will be a bad Negative connection that causes electrical problems in an old car. All Positive connections are made through conductors that travel from the device through a switch and to the Positive source. When I rewired both of my cars I ran a Black wire throughout the car for all my Negative connections. I've never had a problem.

 

BING BING BING, WINNER WINNER HE GETS A CHCKEN DINNER.

Before somewhere well into the 60's the park lights didn't stay on when you turned the headlights on as the switch wasn't designed for it. That is most every American car out there not just Fords.
Most guys who want the park lights on on older rigs move the park light wire over to the tail light post along with the tail light wire.

 

That only works if you have a battery and system that is Negative ground. Many older rigs were and are positive ground and that is why we say "ground" rather than confusing the issue with some********* about "Negative", because it isn't always the negative side.

 

I get it, the way it's been described for eons is ground. It's funny that Ford actually had it right when they used the car as the Positive connection. DC voltage travels from the Negative to the Positive on the outside of the battery. On the inside of the Battery the voltage flows from the Positive to the Negative. I'm just so used to seeing these posts with electrical problems mostly always end up with a bad connection to the Negative of the battery. No matter how it is said, it is as simple as that.

 

So if I did that, the park lights would be on at the same time as the headlights, correct?

 

Yes they would. I did my 56 that way in 68 when I was in high school.

 

Let's just say this thread came out positive, the park light is now grounded and it works. HRP