740 day running lights

  • Thread starter Thread starter Mungo \two sheds\ Toadfoot
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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
 
Mungo "two sheds" Toadfoot said:
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
Click to expand...

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.
 
Steptoe said:
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.
Click to expand...

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 said:
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?
Click to expand...


*Thinks*

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

Si
 
Mungo "two sheds" Toadfoot said:
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
Click to expand...

You've probably got a bad ground connection at the light.
 
James said:
You've probably got a bad ground connection at the light.
Click to expand...

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
 
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).
 
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.
Click to expand...
Sounds like classic symptoms of an earth fault.
 
Mungo "two sheds" Toadfoot said:
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?
Click to expand...

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
 
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
Click to expand...

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.
 
Mungo "two sheds" Toadfoot said:
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
Click to expand...

iirc they use a special bulb, NOT a stop tail (very similar)
 
James Sweet said:
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.
Click to expand...

Rear lights is also on with DRL so they would have had to separate tail and
front parking lights.

What is the problem?

The solution has one bonus: When the 21 W filament goes out there is still
some light from the 5 W.

/aw
 
Anders Wiklund said:
The solution has one bonus: When the 21 W filament goes out there is still
some light from the 5 W.
Click to expand...

yes it's normal, I had an old Saab 99 and both filaments were lit. I much
preferred those DRL's to the permanent headlamp ones.
 
Mungo "two sheds" Toadfoot said:
Are both filaments supposed to be lit when the day lights are on or just the
21w one?

Si
Click to expand...

My C reg 740 had double filament dlrs. the 21w lit with no other lights on
and the 5w lit when headlights were switched on. My G & J reg used single
filament 21w bulbs that go out with headlights on.
 
The Canada Safety Council disagrees with your preference and option provided
by OEMs. They prefer normal headlights on. The purpose of DRL is help
make an oncoming driver aware of your presence on the road. Regardless of
the cost of the bulbs it is very inexpensive if it prevents an on coming car
from getting in your way. An accident between on coming cars at closing
speed of 225 KPH or 140 MPH would not be a very pleasant experience even in
a Volvo.

My Volvo setting is "headlights on". Day or night I do not think about
headlights at all. One less thing to remember
 
The message <[email protected]>
from "Gunner said:
The Canada Safety Council disagrees with your preference and option
provided
by OEMs. They prefer normal headlights on. The purpose of DRL is help
make an oncoming driver aware of your presence on the road.
Click to expand...

Though research is now being conducted into whether the unintended
consequence of this is that drivers concentrate more on the cars with
lights and fail to notice pedestrians and bikes. Early indications
(IIRC) show that this is the case.
 
Eh?

I think you'll find that DRL are better than OEM headlights. Headlights are
for when it is dark, period.

Hammo
 
The message <BF7B4A06.13072%[email protected]>
from Hamish Alker-Jones said:
Headlights are for when it is dark, period.
Click to expand...

That may be true in Australia, but in the UK it's different.

Rule 201: You MUST use headlights when visibility is seriously reduced,
generally when you cannot see for more than 100 metres (328 feet). You
may also use front or rear fog lights but you MUST switch them off when
visibility improves.

http://www.highwaycode.gov.uk/21.htm#211
 
Gunner said:
The Canada Safety Council disagrees with your preference and option
provided by OEMs. They prefer normal headlights on. The purpose of DRL
is help make an oncoming driver aware of your presence on the road.
Regardless of the cost of the bulbs it is very inexpensive if it prevents
an on coming car from getting in your way. An accident between on coming
cars at closing speed of 225 KPH or 140 MPH would not be a very pleasant
experience even in a Volvo.

My Volvo setting is "headlights on". Day or night I do not think about
headlights at all. One less thing to remember
Click to expand...

Dipped light isnt designed to be seen they ar for seeing.
This problem is obvious with Xenon lights, they have poor visibility.
Maybe thats why Hella has introduced DRLs:
http://www.tagfahrlicht.de/daytime-running-lights/
 
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