Possible culprits behind intermittent headlight loss?

Post by Doc
Have a '66 Fairlane wagon, the headlights will blank out after maybe
15 - 20 minutes on low beam. Turning the switch off for a few secs and
then turning on will typically get them back on temporarily but
they'll continue to go out. Further, hitting the hi beams is almost
guaranteed to kill the lights. Replaced the switch and the floor
dimmer, neither cures the problem.
Any suggestions as to where to begin looking?
Thanks.

I have a similar problem with the radio, turn it on, plays for about 10 sec
then goes away. Thouth it was a bad fuse, some will do that. But that did
not fix it.

Ashton Crusher

2007-06-20 02:25:39 UTC

On my 64 T-bird I found some of the crimps in the fuse block were no
longer tight and had to solder them.

Jim Warman

2007-06-20 02:39:40 UTC

What are you running for headlights or other lights hooked to "that"
circuit? The headlight switch contains a circuit breaker for the headlight
circuits only and your concern indicates high current flow in the system

Erik

2007-06-20 02:53:13 UTC

Don't most older cars have self resetting breakers for the headlight
circuit/s? Seems I remember them ocassionly cycling on and off...

Do you have a factory shop manual for it? If not, google up "Faxon Auto
Literature". They more than likely have one in stock.

Good Luck!

Erik

Sharon Cooke

2007-06-20 11:13:33 UTC

It’s a worn circuit breaker contained IN the headlight switch. The usual
fix is to replace the switch with a new one. Go one step further after
that and install headlight relays to take almost the entire load off the
switch, and the headlight switch will outlast the car. Much brighter
lights, too.

Doc

2007-06-20 11:24:15 UTC

Post by Sharon Cooke
Go one step further after
that and install headlight relays to take almost the entire load off the
switch, and the headlight switch will outlast the car. Much brighter
lights, too.

Thanks - can you advise more details on this - what's involved, where
to find the pieces etc.

Sharon Cooke

2007-06-20 17:25:17 UTC

Post by Sharon Cooke

The headlight switch is a standard auto parts place item, even for a 40+
year old Ford. The relay is available there also, or you can buy a
pre-wired harness from someplace like www.autodynamic.com that simply
‘plugs in’.

You can get the relay info by typing
headlight relays
into your browser search engine.

Comboverfish

2007-06-20 12:32:54 UTC

Did you inspect the female terminals' tension at the dimmer switch
harness? Are they corroded or clean? Other than that, you most
likely have high resistance somewhere common to both bulbs. This
could be a poor ground, splice, fuse holder, etc. in the system.

I don't know what kind of fuse protection is used on your Fairlane,
but *if* it uses a circuit breaker, the breaker could be faulty, or
the contacts between the fuse box and breaker could be loose which
would heat up the breaker and trip it thermally.

Toyota MDT in MO

dahpater

2007-06-20 12:44:26 UTC

On the old cars, (especially fords), it was usually a bad headlight
switch.

Mike Romain

2007-06-20 14:10:46 UTC

I see that happen to old vehicle when folks try to run halogen bulbs in
them without adding a power relay.

The bimetal circuit breakers in the old switches cannot take the amp
draw the modern halogen bulbs draw.

The old time conversion kits that were sold when halogens first came out
are a simple Bosch relay that is fused to the battery and wired so the
switch is just the trigger for the relay.

Here is a site on how to wire one in.
http://www.classictruckshop.com/clubs/earlyburbs/projects/bosch/relay.htm

The other reason I see the breaker cook is a bad connection in the plug
for the headlight switch. The main power wire's spade connector can get
ratty which will cause arcs and heat and breaker failure.

I see this same bad connection on the floor dimmer switch plugs.

And last, a bad ground can cause heat issues. I would verify the
headlight ground tags and the body's main ground from the battery.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's - Gone to the rust pile...
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590
(More Off Road album links at bottom of the view page)

Ashton Crusher

2007-06-20 16:59:13 UTC

There is almost no difference in the current draw between the old
bulbs and halogen.

Post by Mike Romain
Here is a site on how to wire one in.
http://www.classictruckshop.com/clubs/earlyburbs/projects/bosch/relay.htm
The other reason I see the breaker cook is a bad connection in the plug
for the headlight switch. The main power wire's spade connector can get
ratty which will cause arcs and heat and breaker failure.
I see this same bad connection on the floor dimmer switch plugs.
And last, a bad ground can cause heat issues. I would verify the
headlight ground tags and the body's main ground from the battery.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's - Gone to the rust pile...
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590
(More Off Road album links at bottom of the view page)

Mike Romain

2007-06-20 17:29:04 UTC

There is almost no difference in the current draw between the old
bulbs and halogen.

There is enough difference to blow the bimetal circuit breaker,
especially when the high beams kick in. There is a 'reason' we needed
the conversion kits, every one I have seen without it has sooner than
later cooked the switch.

Some kits (one for my 1970 Pontiac Safari Wagon) even wired the relay in
parallel with the light switch circuit so the headlights got two power
sources which was enough to keep that bimetal switch cool.

Ashton Crusher

2007-06-21 04:46:01 UTC

There is almost no difference in the current draw between the old
bulbs and halogen.

There is enough difference to blow the bimetal circuit breaker,
especially when the high beams kick in. There is a 'reason' we needed
the conversion kits, every one I have seen without it has sooner than
later cooked the switch.
Some kits (one for my 1970 Pontiac Safari Wagon) even wired the relay in
parallel with the light switch circuit so the headlights got two power
sources which was enough to keep that bimetal switch cool.

There was a long discussion of this in a T-bird group. With the
headlights from 66 bird what was measured...

with a battery charge of 12.6 static volts...
"Old" style headlamp.... low beam: 2.2A. @12.18V,......... high
beam:4.2A.
@12.07V.
"Halogen" headlamp.... low beam:***@...,.......... high
beam:***@....

So the maximum draw with the halogens was actually LESS then with the
old style bulbs. Not really surprising since one of the benefits of
the halogen bulbs was that they are more efficient so for the same
legal max output they actually draw LESS current. The newer bulbs had
brighter low beams, that's why the low beam current was higher, but
still less then on high beams which is the max current draw when all
four bulbs are lit up.

Mike Romain

2007-06-21 14:04:15 UTC

There is almost no difference in the current draw between the old
bulbs and halogen.

There is enough difference to blow the bimetal circuit breaker,
especially when the high beams kick in. There is a 'reason' we needed
the conversion kits, every one I have seen without it has sooner than
later cooked the switch.
Some kits (one for my 1970 Pontiac Safari Wagon) even wired the relay in
parallel with the light switch circuit so the headlights got two power
sources which was enough to keep that bimetal switch cool.

There was a long discussion of this in a T-bird group. With the
headlights from 66 bird what was measured...
with a battery charge of 12.6 static volts...
beam:4.2A.
@12.07V.
So the maximum draw with the halogens was actually LESS then with the
old style bulbs. Not really surprising since one of the benefits of
the halogen bulbs was that they are more efficient so for the same
legal max output they actually draw LESS current. The newer bulbs had
brighter low beams, that's why the low beam current was higher, but
still less then on high beams which is the max current draw when all
four bulbs are lit up.

Real life says someone is playing fast and loose with the numbers!

Got any 'real' numbers for the watts of the bulbs, not something someone
made up with who know what kind of skill or meter?

Once again I will say 'every' old vehicle I have seen with halogens that
were not included stock burns up the headlight switch unless the
conversion kit or a relay is used!

I see this 'lots' due to being a wiring tech for a owner owned fleet of
old vans on one 9 year contract and all the old Jeeps I play with and
repair.

On the fleet I would have to hot wire one or two headlights a year so
they could deliver that night when their switches smoked out. It was
the Ford switches that went the most, followed close by the GM switches.

Scott Dorsey

2007-06-21 14:08:09 UTC

Post by Ashton Crusher
There is almost no difference in the current draw between the old
bulbs and halogen.

On many American cars, the current supply for the lamps was very marginal.
Going to a halogen doesn't pull a lot more current, but it still pulls
too much more.

This is opposed to some British cars where the switches just burn up all
the time anyway, even using the stock lamps.

Post by Mike Romain
Some kits (one for my 1970 Pontiac Safari Wagon) even wired the relay in
parallel with the light switch circuit so the headlights got two power
sources which was enough to keep that bimetal switch cool.

Hmm, that's a cute idea. I like that.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Sharon Cooke

2007-06-21 15:50:00 UTC

Post by Scott Dorsey

Post by Ashton Crusher
There is almost no difference in the current draw between the old
bulbs and halogen.

On many American cars, the current supply for the lamps was very marginal.
Going to a halogen doesn't pull a lot more current, but it still pulls
too much more.
This is opposed to some British cars where the switches just burn up all
the time anyway, even using the stock lamps.

Hmm, that's a cute idea. I like that.
--scott

The CB built into all the Ford headlight switches even back in the '60s
was rated at 22 amps, which was plenty of capacity to run all the
exterior lights, when new; the main real culprit is age, affecting
current draw and CB reliability. In the case of Ford, it was compounded
by using marginal quality parts and very light gauge wire; there's a
reason why it's always been called the "Ford flashing headlight
syndrome", even though other makes have reportedly done it (just not as
much).

Doc

2007-06-26 22:04:04 UTC

Just as a follow up, replacing the headlight switch so far seems to
have cured the problem. Curious since the one that was in there wasn't
that old.

Thanks again to all who replied.

Dear Leader @ Ryugyong Hotel

2007-07-26 23:51:23 UTC

Post by Doc
Just as a follow up, replacing the headlight switch so far seems to
have cured the problem. Curious since the one that was in there wasn't
that old.

cheap china stuff.

Les Benn

2007-07-27 03:49:32 UTC

Post by Dear Leader @ Ryugyong Hotel

Post by Doc
Just as a follow up, replacing the headlight switch so far seems to
have cured the problem. Curious since the one that was in there wasn't
that old.

cheap china stuff.

only problem is the headlights point straight up when using Chinese lights
since they are calibrated on the wrong side of the planet.

Mike Romain

2007-07-27 13:34:08 UTC