Mungo \two sheds\ Toadfoot

A small problem: The "knackered bulb" indicator in the car is lit but goes
off if the sidelights or headlights are switched on, indicating a fault with
a day-running light.

One day-running light is brighter than the other because *both* filaments
(stop and tail bulb - 21w/5w) are lit and the other only has the 5w filament
lit. If I turn the sidelights on then only the 5w filaments are lit, both
sides. The bulb *looks* fine but I haven't got a replacement to hand, nor a
tester, which is at someone else's house at the moment.

Are both filaments supposed to be lit when the day lights are on or just the
21w one?

Si

Steptoe

"Mungo "two sheds" Toadfoot" <ufdi@hotmail.com> wrote in message
news:o62dnT-g6aaZFM_eRVnytA@pipex.net...
> A small problem: The "knackered bulb" indicator in the car is lit but goes
> off if the sidelights or headlights are switched on, indicating a fault
with
> a day-running light.
>
> One day-running light is brighter than the other because *both* filaments
> (stop and tail bulb - 21w/5w) are lit and the other only has the 5w
filament
> lit. If I turn the sidelights on then only the 5w filaments are lit, both
> sides. The bulb *looks* fine but I haven't got a replacement to hand, nor
a
> tester, which is at someone else's house at the moment.
>
> Are both filaments supposed to be lit when the day lights are on or just
the
> 21w one?
>
> Si
>
>

Hard to tell as you get reflection from the 21 to the 5 but I am sure only
the 21 should be on; failure of the 21 is the commonest fault.

Mungo \two sheds\ Toadfoot

Steptoe wrote:

>> Are both filaments supposed to be lit when the day lights are on or
>> just the 21w one?
>>
>
> Hard to tell as you get reflection from the 21 to the 5 but I am sure
> only the 21 should be on; failure of the 21 is the commonest fault.

I'm fairly sure they were both lit but I could be wrong - it's difficult to
look at a 21w bulb!

If they *are* both lit any idea why this might be?

Si

Mungo \two sheds\ Toadfoot

Mungo "two sheds" Toadfoot wrote:
> Steptoe wrote:
>
>>> Are both filaments supposed to be lit when the day lights are on or
>>> just the 21w one?
>>>
>>
>> Hard to tell as you get reflection from the 21 to the 5 but I am sure
>> only the 21 should be on; failure of the 21 is the commonest fault.
>
> I'm fairly sure they were both lit but I could be wrong - it's
> difficult to look at a 21w bulb!
>
> If they *are* both lit any idea why this might be?
>


*Thinks*

Dodgy wiring, switch, or holder, innit? Bugger. I hate electrics.

Si

James Sweet

"Mungo "two sheds" Toadfoot" <ufdi@hotmail.com> wrote in message
news:o62dnT-g6aaZFM_eRVnytA@pipex.net...
> A small problem: The "knackered bulb" indicator in the car is lit but goes
> off if the sidelights or headlights are switched on, indicating a fault
with
> a day-running light.
>
> One day-running light is brighter than the other because *both* filaments
> (stop and tail bulb - 21w/5w) are lit and the other only has the 5w
filament
> lit. If I turn the sidelights on then only the 5w filaments are lit, both
> sides. The bulb *looks* fine but I haven't got a replacement to hand, nor
a
> tester, which is at someone else's house at the moment.
>
> Are both filaments supposed to be lit when the day lights are on or just
the
> 21w one?
>
> Si
>
>

You've probably got a bad ground connection at the light.

Mungo \two sheds\ Toadfoot

James Sweet wrote:
>
> You've probably got a bad ground connection at the light.

You might be right. I just got in the car and the warning light has gone
out! It's been coming on intermittently for the past few weeks but decided
it was staying on for good recently. Until this evening. Ho hum.

Si

Peter K L Milnes

It is a well known fault of twin filament bulbs that when the earth
connection doesn't quite make good then the other filament acts as an earth
contact. The bulb itself can also fail as a Pontiac GTO owner I diagnosed
for will tell you.

All the best, Peter.

700/900/90 Register Keeper,
Volvo Owners Club (UK).

"Mungo "two sheds" Toadfoot" <ufdi@hotmail.com> wrote in message
news:j4CdnSF3vY3sNs_eRVnygQ@pipex.net...
> James Sweet wrote:
>>
>> You've probably got a bad ground connection at the light.
>
> You might be right. I just got in the car and the warning light has gone
> out! It's been coming on intermittently for the past few weeks but decided
> it was staying on for good recently. Until this evening. Ho hum.
>
> Si
>

SimonJ

> A small problem: The "knackered bulb" indicator in the car is lit but goes
> off if the sidelights or headlights are switched on, indicating a fault
with
> a day-running light.
>
> One day-running light is brighter than the other because *both* filaments
> (stop and tail bulb - 21w/5w) are lit and the other only has the 5w
filament
> lit. If I turn the sidelights on then only the 5w filaments are lit, both
> sides. The bulb *looks* fine but I haven't got a replacement to hand, nor
a
> tester, which is at someone else's house at the moment.
>
Sounds like classic symptoms of an earth fault.

Anders Wiklund

"Mungo "two sheds" Toadfoot" <ufdi@hotmail.com> skrev i meddelandet
news:o62dnT-g6aaZFM_eRVnytA@pipex.net...
>A small problem: The "knackered bulb" indicator in the car is lit but goes
>off if the sidelights or headlights are switched on, indicating a fault
>with a day-running light.
>
> One day-running light is brighter than the other because *both* filaments
> (stop and tail bulb - 21w/5w) are lit and the other only has the 5w
> filament lit. If I turn the sidelights on then only the 5w filaments are
> lit, both sides. The bulb *looks* fine but I haven't got a replacement to
> hand, nor a tester, which is at someone else's house at the moment.
>
> Are both filaments supposed to be lit when the day lights are on or just
> the 21w one?

Yes, both are supposed to lit.
I am 100 % sure, i do have the Volvo electrical diagram book for that car.
I guess Volvo made a shortcut in the design, otherwise they would have had
to arrange with an extra relay to turn the filament for the parking light
off when the day running light is on.

/aw

James Sweet

> Yes, both are supposed to lit.
> I am 100 % sure, i do have the Volvo electrical diagram book for that car.
> I guess Volvo made a shortcut in the design, otherwise they would have had
> to arrange with an extra relay to turn the filament for the parking light
> off when the day running light is on.
>
> /aw
>
>

Seems they would have just arranged the headlight switch to turn off the
small filament, that's how it is on cars without DRL, the parking lamp
filaments are only on when the switch is in park or headlights. When I added
DRL I used a relay to turn them off whenever the parking lamps are powered
since my headlight switch doesn't have provisions for them, it does have
blank spaces where more terminals could have gone though.