Fog Lamp

[BigYin]

where to start????

KerrSurf and I spent a good few hours yesterday trying to sort a knackered rear fog lamp.

Replaced the old lamp with a new one, connected up, nadda....

different bulb - nadda

located the switch, the warning light, the wiring, removed the warning light from the circuit in case that was the problem - nope.

No power at the switch. hmmmm.

Found a cable that wasn't connected to anything, not part of the original loom, that did have 12v when tested from cable to earth.

Tested switch with continuity tester - working.

connected switch to the powered cable, and tested switch to earth - 12v when switch closed, 0v when switch open.

Now, bring lamp into the front (to prove it's a break in the cable from the switch to the rear of the truck) - so power to switch, switch to lamp, lamp to earth.. - NOTHING!!

Continuity tests on bulb and lamp housing connectors all good.

WHAT THE HELL IS GOING ON????

Next thing is to buy a full fog lamp kit - switch and all - and fit that from scratch, using the instructions from that to see what stupid mistake we've been making....!

[BigYin]

Just bought a full kit fog lamp kit from ebay - says it comes with all the bits needed and full instructions, so fingers crossed....

[jpinhorn]

Not all but quite allot of fog lamps only work when your ignition is on and your lights are on dipped beam. It's not an mot requirement for it to work that way but most do. Worth checking.

[Albannach]

It's not an mot requirement for it to work that way

Are you sure?

[jpinhorn]

http://www.motuk.co.uk/manual_110.htm


6. Rear fog lamps
The inspection of rear fog lamps is confined to the one rear fog lamp which is required to be fitted to the centre or offside of
vehicles first used on or after 1 April 1980.
Note: On some vehicles the front fog lamps need to be switched on before the rear fog lamp(s) will work
.
Note: A rear fog lamp is permitted to operate independently of headlamp, position lamp or ignition systems.

Note: at least 50% of light sources in a lamp must illuminate

6. With dipped headlamps and the ignition switched on, operate the rear fog lamp switch and check that a rear fog lamp
. is fitted to the centre or offside of the vehicle

. is working, and

. does not flicker when tapped lightly by hand.

Check also that the drivers tell-tale works properly.

7. Check the presence, condition, security and operation of the switch.
6. A mandatory rear fog lamp
a. is missing, does not emit a steady red light or emits a light other than red
b. incomplete, not in good working order or not visible from a reasonable distance
c. is insecure, obscured or not facing to
the rear
d. flickers when tapped lightly by hand e. tell-tale does not work
f. adversely affected by the operation of
any other lamp.
7. A rear fog lamp switch
a. missing
b. faulty
c. insecure
d. not able to be operated from the normal driving position.

[Albannach]

Yes would have been fine, it's one of the test anomalies. There aren't many left.

[BigYin]

The cable I know has 12v power only has it when the ignition is on - we sussed that early on

It didn't matter whether the lights were on or not - the cable had 12v so long as the ignition was on.

Not going to have time to do anything with it until late on this week - kit needs to arrive first anyway.

[Albannach]

I'm not going to say this is correct, but it is my understanding of the C&U Regs. I think, legally, fog lamps should only be operable on dipped beam (in the same way that Driving lamps should only operate on main beam).

I wasn't aware of the MOT ruling, so I may be wrong here too.

Irrespective of whether I'm right or wrong with regards the law, it's good practice to take the relay switched supply from the dipped beam circuit.

[Bogus]

Yes would have been fine, it's one of the test anomalies. There aren't many left.

Yes would have been fine I suppose but as an answer the one provided was much better. Why do say that its a test anomaly, whats anomalous about it?

Bogus

[Albannach]

Why do say that its a test anomaly, whats anomalous about it?

Nothing with regards the test, but it doesn't seem to match the C&U regs. But I may be wrong; as I posted above.

[wishbone]

Make sure the switch is only used to switch the relay. You can use the dash lights feed to power it. Will only work when the lights are on then.

Rob.

.

[Bogus]

Nothing with regards the test, but it doesn't seem to match the C&U regs. But I may be wrong; as I posted above.

I was typing that question while you posted that one about theC&U regs, and when I read it ( after posting) I realised that you were referring to a possible anomaly between the MOT manual and the C&U regs, so in effect my question was being answered before I asked it.

Bogus

[BigYin]

I'm not going to say this is correct, but it is my understanding of the C&U Regs. I think, legally, fog lamps should only be operable on dipped beam (in the same way that Driving lamps should only operate on main beam).

I wasn't aware of the MOT ruling, so I may be wrong here too.

Irrespective of whether I'm right or wrong with regards the law, it's good practice to take the relay switched supply from the dipped beam circuit.

Current switch location is on the center console, behind the gear shift - I'm a total novice at car electrics, and haven't the first clue how I would locate the dipped beam circuit!

As far as the MOT regs go, a visible 'driver tell-tale' lamp is all that's really required. I'm quite happy to wire it into the powered wire we found as that is only powered up with ignition on, so no risk of leaving the lamp on with the ignition off and draining the battery!!

I think that's good enough for the MOT, and saves me worrying about where to draw power from the lamp from

[Albannach]

Current switch location is on the center console, behind the gear shift - I'm a total novice at car electrics, and haven't the first clue how I would locate the dipped beam circuit!

As far as the MOT regs go, a visible 'driver tell-tale' lamp is all that's really required. I'm quite happy to wire it into the powered wire we found as that is only powered up with ignition on, so no risk of leaving the lamp on with the ignition off and draining the battery!!

I think that's good enough for the MOT, and saves me worrying about where to draw power from the lamp from

The fog lamp switch there is usually for front fogs, not the rear? The rear tends to be a switch near the idle up button, so the driver can see the tell-tale.

[BigYin]

no front fogs installed - probably used to be - the switch is there, but not connected to anything.

The aftermarket rear fog is definately wired to the switch I mentioned - we traced the wire to it!!