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Omega Help Area => Omega General Help => Topic started by: terry paget on 18 June 2019, 14:35:00

Title: Rear fog lights not working. Fuse 28 OK
Post by: terry paget on 18 June 2019, 14:35:00
2003 3.2 manual ex-police car.
MOT tester observes neither rear fog light illuminates. I have checked fuse 28, it's OK. Is there a relay?
Title: Re: Rear fog lights not working. Fuse 28 OK
Post by: Enceladus on 18 June 2019, 17:05:09
If it's a saloon also check the wiring loom that feeds the left of the boot lid. By the hinge. It breaks there and then you get funnies with lights.
Title: Re: Rear fog lights not working. Fuse 28 OK
Post by: Andy B on 18 June 2019, 17:05:40
wiring over the boot hinge?
or the black/blue bridging wire in the back of the boot on what would be the supply to caravan/trailer wiring is where I'd be looking first.
Title: Re: Rear fog lights not working. Fuse 28 OK
Post by: TheBoy on 18 June 2019, 18:08:32
You are trying with the headlights on?
Title: Re: Rear fog lights not working. Fuse 28 OK
Post by: Migv6 le Frog Fan on 18 June 2019, 18:51:44
Good point.  :y...……...not that Ive ever made a mistake like that.  :-X
It isn't possible to make this mistake in the old 190. Designed in the time when Mercedes knew how to design and build cars better than everyone lese did.  :)
Title: Re: Rear fog lights not working. Fuse 28 OK
Post by: terry paget on 18 June 2019, 18:58:30
You are trying with the headlights on?
Yes. The indicator light in the speedometer comes on, but not the rear fogs. The front spots com on normally, along with their speedo indicator.
Title: Re: Rear fog lights not working. Fuse 28 OK
Post by: Andy B on 18 June 2019, 19:07:45
Good point.  :y...……...not that Ive ever made a mistake like that.  :-X
It isn't possible to make this mistake in the old 190. Designed in the time when Mercedes knew how to design and build cars better than everyone lese did.  :)
Is this the same Mercedes that had the tell tale for the lights & fog lights on the switch that informs your right knee that the lights/fog lights are on? (think early Omegas vs later Omegas  ;)) At least they sorted it for my later ML  :y

 Also, the same Mercedes that illuminate the rotary parts of the lights switch but not the static part? In the dark, you can see what you're moving, but not what you're moving it to.  ::)

Title: Re: Rear fog lights not working. Fuse 28 OK
Post by: robson on 19 June 2019, 09:00:16
mine was boot broken wire near boot hinge :y
Title: Re: Rear fog lights not working. Fuse 28 OK
Post by: terry paget on 19 June 2019, 10:44:56
Thanks for all tips. I have found the wires by the boot hinge; Haynes confirms that blue/black wire is the feed to the rear fog lights; no wire is broken near the hinge, disappointing. I thought I would check volts at this point; I have done this in the past by thrusting  needle through the insulation, but it's not easy, what I need is a tool I can easily push through the insulation. Please advise.
Title: Re: Rear fog lights not working. Fuse 28 OK
Post by: Nick W on 19 June 2019, 11:51:58
Thanks for all tips. I have found the wires by the boot hinge; Haynes confirms that blue/black wire is the feed to the rear fog lights; no wire is broken near the hinge, disappointing. I thought I would check volts at this point; I have done this in the past by thrusting  needle through the insulation, but it's not easy, what I need is a tool I can easily push through the insulation. Please advise.


you can buy them ready to plug into your multimeter. Mine came as part of an expensive set, but they're cheap on Ebay.
Title: Re: Rear fog lights not working. Fuse 28 OK
Post by: terry paget on 19 June 2019, 15:11:17
Thanks Nick. There were some in my mulimeter box, I just had not identified them.
I can detect no volts on the blue-black lead at the boot hinge, rear fogs switched on. I can detect volts on the reversing light black-white lead, reversing lights on.

I removed again fuse 28, still looks good and shows continuity on the meter, I was about to check 12 volts one side of the fuse, but found that without the fuse in place the warning light does not light. Conclusion - there is power one side of the fuse.

There is therefore a break between the switch and the rear hinge.

Do the wires go along the nearside sill?
Title: Re: Rear fog lights not working. Fuse 28 OK
Post by: Doctor Gollum on 19 June 2019, 15:14:36
Yes. But it's a moot point.
Title: Re: Rear fog lights not working. Fuse 28 OK
Post by: Doctor Gollum on 21 June 2019, 21:44:42
Try this...

http://www.omegaowners.com/forum/index.php?topic=66602.0 ;)
Title: Re: Rear fog lights not working. Fuse 28 OK
Post by: Doctor Gollum on 22 June 2019, 01:05:02
Try this...

http://www.omegaowners.com/forum/index.php?topic=66602.0 ;)
To add, it might be that the pins are corroded and causing the fogs to not work.
Title: Re: Rear fog lights not working. Fuse 28 OK
Post by: Doctor Gollum on 22 June 2019, 12:13:52
And not to overlook the obvious...

Are the bulbs OK?