electrically stupid

"ThaDriver" <imangeloneAThotmailDOTcom@> wrote in message
lkaboutautos.com...
> > They'll both pass current through *both* filaments, but you'll only see
> > one of them glowing (the smaller one)
> >
> > nate
> >
> > --
> > replace "fly" with "com" to reply.
> > http://home.comcast.net/~njnagel
>
>
> Separately, how does this current in both circuits thing work. I don't
> have
> anything showing on the second circuit with a test light, and I'm not
> registering anything on the multimeter. If there is supposed to be
> current
> in both circuits, does that mean there is a common area where the light
> switch and the brake switch could be connected or close together? Do you
> know where that would be?
> *******
> Ignore what Nate said. Apparently he hasn't read your posts where you said
> only one circuit has current, & both the brake/turn & taillight is feeding
> that circuit.
> If at this point you're still not getting current in one of the curcuits,
> it must be either a bad turn signal switch or crossed wires somewhere in
> the loom. Use a continuity tester (disconnect the car's battery) to check
> what will carry current to where.
> ~ Paul
> aka "Tha Driver"
>
> Easy on the Giggle Cream!

I'm on it. I'd still like to get that brake switch out, too, and replaced.
But, damn, it's hard laying upside down, half in and half out of the car.
I'll let you know what turns up.

>But, damn, it's hard laying upside down, half in and half out of the car.
I'll let you know what turns up.
*********
I can dig it. It didn't use to be a problem for me, but at 50+ I have a
hard time crawling under the dashes too - especially on these "newer" cars
with all the crap they put in there now...
~ Paul
aka "Tha Driver"

Giggle Cream - it makes dessert *funny*!

Okay. Now, for the bulb itself, a few things have changed and a few things
haven't. There is still only one filament being used in the bulb by both
the tail light and the brake/blinker light. However, each system works if I
turn it on independently. All three light-requiring functions use the lower
of the two filaments in the bulb.

On the right bulb, the running or tail lights utilize the top filament, and
the brake/blinker uses the bottom filament.

Currently, I can have the brake or blinker on and turn on the tail lights
and it no longer goes dead. If the blinker is on, it keeps blinking, but at
a much slower rate. The other filament doesn't light, so I don't know if
current is coming into that bulb for the tail light and being diverted to
the brake/blinker filament, but it certainly appears that way.

In all cases, the bulb on the left is much, much dimmer than the bulb on the
right, and if I try two functions, the left bulb gets even dimmer.

If it weren't for the fact that the tail lights and brake/blinker lights are
sharing the filament or circuit, it sure would look like a ground problem.
But, they are sharing the circuit somehow, AND the circuit being shared
lights the opposite filament in the left bulb than it does in the right
bulb.

My back is broken. No change out yet on the brake switch. I cannot find
anything obvious. So, it's obviously hiding.

More food for thought:

Are both bulbs (right and left) the same type? Have you switched or
replaced them to make certain the problem doesn't follow the bulb?

I am not that familiar with a 77:

- are the inner (backup) lamps essentially the same as a tail light?
Ie, is there a completely different type of bulb and socket in the
backup lamps, or is the backup lamp essentially the same as a tail lamp
except that it has a different lens and the wires that go to it only
activate the bright (or both) filament(s) when the car is put in reverse?

- Is the socket part of the tail lamp assembly, or is it part of the
wiring harness?

- how difficult is it to get at the wiring from behind the lamps (can
you reach them to disconnect them, or can you unbolt and move the tail
lamp housing out far enough to disconnect the harness)?

My thinking here is that IF the wiring connector is separate from the
socket, and you have a bad socket (which can easily happen as moisture
corrodes the hidden insides of the fixture over time), then you might be
able to test for that in several ways...

1. switch the connectors between the lamp housings (tail light and
backup light) and see if the problem follows the wiring harness
connector (ie, the backup lamp would behave as a tailight), or...

2. Similarly, if the wiring harness is accessible and it runs from the
left side across the back end to the right side, and if you could free
the harness to get enough slack, you could connect the right-side
harness to the left-side housing to see if the problem persists (or use
test leads to do the same thing) when the right blinker and brakes and
lights are on, which would again indicate a housing/socket issue. Or...

3. Similarly again, if the connector can be removed from the socket,
that would isolate the harness from the bulb socket; then just test the
leads in the connector by using use 3 test leads to connect a loose tail
lamp bulb to the harness connector to see if the bulb functions normally.

If the wiring harness connector is not separate, but integral with the
bulb socket and the socket plugs into the housing, then probably the
only way to test for a bad socket is to cut the attaching wires, test
the harness wires with a loose bulb (as in 3, above), and/or test the
socket by checking for continuity between the cut socket wires with the
bulb removed (I think all 3 should be independent, no continuity between
them) and re-splice the harness wires.


BDragon wrote:
> Okay. Now, for the bulb itself, a few things have changed and a few things
> haven't. There is still only one filament being used in the bulb by both
> the tail light and the brake/blinker light. However, each system works if I
> turn it on independently. All three light-requiring functions use the lower
> of the two filaments in the bulb.

That's probably not good. The rhetorical question is, where is the
current leakage across to the lower filament... at the light fixture or
further upstream?
>
> On the right bulb, the running or tail lights utilize the top filament, and
> the brake/blinker uses the bottom filament.
>
> Currently, I can have the brake or blinker on and turn on the tail lights
> and it no longer goes dead. If the blinker is on, it keeps blinking, but at
> a much slower rate. The other filament doesn't light, so I don't know if
> current is coming into that bulb for the tail light and being diverted to
> the brake/blinker filament, but it certainly appears that way.

You don't really mean the "bulb" do you? Surely you have swapped or
changed out the bulb already, so the problem has to be outside the bulb.
And, surely you have used a multimeter to check the voltage at both
terminals inside the socket while varying the lights, signals, brakes.

>
> In all cases, the bulb on the left is much, much dimmer than the bulb on the
> right, and if I try two functions, the left bulb gets even dimmer.
>
> If it weren't for the fact that the tail lights and brake/blinker lights are
> sharing the filament or circuit, it sure would look like a ground problem.
> But, they are sharing the circuit somehow, AND the circuit being shared
> lights the opposite filament in the left bulb than it does in the right
> bulb.
>
> My back is broken. No change out yet on the brake switch. I cannot find
> anything obvious. So, it's obviously hiding.
>
>

Ok let me double-check this; Have you unplugged the socket to that
taillight & tested the feed(s) using a 12v volt test light? I believe you
said you have but I want to re-check that anyway. If you have, & there is
only one wire getting current from both circuits, find those wires where
they enter the cabin (near the dash) & check them there. If only one wire
gets current from both circuits there then it must(?) be in the fusebox or
a switch...
~ Paul
aka "Tha Driver"

Giggle Cream - it makes dessert *funny*!

Ok let me double-check this; Have you unplugged the socket to that
taillight & tested the feed(s) using a 12v volt test light? I believe you
said you have but I want to re-check that anyway. If you have, & there is
only one wire getting current from both circuits, find those wires where
they enter the cabin (near the dash) & check them there. If only one wire
gets current from both circuits there then it must(?) be in the fusebox or
a switch...(or under-dash wiring..)
~ Paul
aka "Tha Driver"

Giggle Cream - it makes dessert *funny*!

BDragon spoke thusly...

> My back is broken. No change out yet on the brake switch. I cannot find
> anything obvious. So, it's obviously hiding.
>
What was the quote from Sherlock Holmes? Something about once you have
eliminated every possible explanation, it's time to look at the
impossible ones, or something to that effect...

--
-|>|- Diode -|<|-
'68 L-79 Coupe
'79 Triumph Bonneville
Shut up, dave.
Professional driver on a closed course. Do not attempt.
Actual mileage may vary.

"WayneC" > wrote in message
...
> More food for thought:
>
> Are both bulbs (right and left) the same type? Have you switched or
> replaced them to make certain the problem doesn't follow the bulb?

I have put new bulbs into each socket.
>
> I am not that familiar with a 77:
>
> - are the inner (backup) lamps essentially the same as a tail light?
The backup lights are separate from the tail lights.

> Ie, is there a completely different type of bulb and socket in the
> backup lamps, or is the backup lamp essentially the same as a tail lamp
> except that it has a different lens and the wires that go to it only
> activate the bright (or both) filament(s) when the car is put in reverse?
>
> - Is the socket part of the tail lamp assembly, or is it part of the
> wiring harness?

No positive I understand this. The wires run out of the loom and directly
into the socket where they attach to the terminals that connect to the
bottom of the bulb.l
>
> - how difficult is it to get at the wiring from behind the lamps (can
> you reach them to disconnect them, or can you unbolt and move the tail
> lamp housing out far enough to disconnect the harness)?

There isn't a place to disconnect from the harness. The wires run all the
way from up front to the rear.
>
> My thinking here is that IF the wiring connector is separate from the
> socket, and you have a bad socket (which can easily happen as moisture
> corrodes the hidden insides of the fixture over time), then you might be
> able to test for that in several ways...

I have put a new socket in with no change to the problem.
>
> 1. switch the connectors between the lamp housings (tail light and
> backup light) and see if the problem follows the wiring harness
> connector (ie, the backup lamp would behave as a tailight), or...
>
> 2. Similarly, if the wiring harness is accessible and it runs from the
> left side across the back end to the right side, and if you could free
> the harness to get enough slack, you could connect the right-side
> harness to the left-side housing to see if the problem persists (or use
> test leads to do the same thing) when the right blinker and brakes and
> lights are on, which would again indicate a housing/socket issue. Or...
>
> 3. Similarly again, if the connector can be removed from the socket,
> that would isolate the harness from the bulb socket; then just test the
> leads in the connector by using use 3 test leads to connect a loose tail
> lamp bulb to the harness connector to see if the bulb functions normally.
>
> If the wiring harness connector is not separate, but integral with the
> bulb socket and the socket plugs into the housing, then probably the
> only way to test for a bad socket is to cut the attaching wires, test
> the harness wires with a loose bulb (as in 3, above), and/or test the
> socket by checking for continuity between the cut socket wires with the
> bulb removed (I think all 3 should be independent, no continuity between
> them) and re-splice the harness wires.

Apparently the problem is further upstream and the socket itself tests okay,
but the current coming to it does not light up the one side or filament.
>
>
> BDragon wrote:
> > Okay. Now, for the bulb itself, a few things have changed and a few
things
> > haven't. There is still only one filament being used in the bulb by
both
> > the tail light and the brake/blinker light. However, each system works
if I
> > turn it on independently. All three light-requiring functions use the
lower
> > of the two filaments in the bulb.
>
> That's probably not good. The rhetorical question is, where is the
> current leakage across to the lower filament... at the light fixture or
> further upstream?

Apparently further upstream.
> >
> > On the right bulb, the running or tail lights utilize the top filament,
and
> > the brake/blinker uses the bottom filament.
> >
> > Currently, I can have the brake or blinker on and turn on the tail
lights
> > and it no longer goes dead. If the blinker is on, it keeps blinking,
but at
> > a much slower rate. The other filament doesn't light, so I don't know
if
> > current is coming into that bulb for the tail light and being diverted
to
> > the brake/blinker filament, but it certainly appears that way.
>
> You don't really mean the "bulb" do you? Surely you have swapped or
> changed out the bulb already, so the problem has to be outside the bulb.
> And, surely you have used a multimeter to check the voltage at both
> terminals inside the socket while varying the lights, signals, brakes.

I didn't say this well. I don't mean the diversion is occuring in the bulb
itself, but somewhere before it gets to the bulb.
>
> >
> > In all cases, the bulb on the left is much, much dimmer than the bulb on
the
> > right, and if I try two functions, the left bulb gets even dimmer.
> >
> > If it weren't for the fact that the tail lights and brake/blinker lights
are
> > sharing the filament or circuit, it sure would look like a ground
problem.
> > But, they are sharing the circuit somehow, AND the circuit being shared
> > lights the opposite filament in the left bulb than it does in the right
> > bulb.
> >
> > My back is broken. No change out yet on the brake switch. I cannot
find
> > anything obvious. So, it's obviously hiding.
> >
> >

"ThaDriver" <imangeloneAThotmailDOTcom@> wrote in message
lkaboutautos.com...
> Ok let me double-check this; Have you unplugged the socket to that
> taillight & tested the feed(s) using a 12v volt test light? I believe you
> said you have but I want to re-check that anyway. If you have, & there is
> only one wire getting current from both circuits, find those wires where
> they enter the cabin (near the dash) & check them there. If only one wire
> gets current from both circuits there then it must(?) be in the fusebox or
> a switch.
> ~ Paul
> aka "Tha Driver"
>
> Giggle Cream - it makes dessert *funny*!
>
I have unplugged the socket and tested the feeds using the mutimeter,
mainly just checking for voltage. Only one wire receives anything. And
no matter what I check, it seems as if I'm just going to have to camp under
the steering wheel for a while. I agree on the switch probability. I still
haven't taken the brake switch out and replaced it. By the time I get
squared away under there, all the wires are about two inches from my
face and I can only get one arm under there so I can't hold one thing while
I pull on another. I'm starting to think just pulling the dash might be
easier.
I've done it before and while it took some time, it wasn't all that bad.
Just
a bowl of spaghetti. I've got to get my shop manual out and see if I can do
the brake switch by braille.

"Diode" > wrote in message
...
> BDragon spoke thusly...
>
> > My back is broken. No change out yet on the brake switch. I cannot
find
> > anything obvious. So, it's obviously hiding.
> >
> What was the quote from Sherlock Holmes? Something about once you have
> eliminated every possible explanation, it's time to look at the
> impossible ones, or something to that effect...
>
> --
> -|>|- Diode -|<|-
> '68 L-79 Coupe
> '79 Triumph Bonneville
> Shut up, dave.
> Professional driver on a closed course. Do not attempt.
> Actual mileage may vary.

The scary part for me now is discovering that the problem is so incredibly
obvious I missed it. That will be after I tear everything apart, of course.

It's been getting down to under 20 degrees here and my hands freeze up
pretty quickly so this whole thing is taking way too long.