Z3M Roadster rear fog light relay

[farside]

Hi all
Recently bought a 1998 Z3M roadster and trying to rectify a problem with the rear fog lights. As it is an 'M' front fogs aren't fitted. The original switch had been replaced by a rocker switch (latching type), and the rear fogs work ok. I found the original switch which had been left in the glove box and discovered one of the brass contacts had come adrift internally, which I fixed. However, it is a non-latching (momentary) switch, and when fitted the fogs only work if the button is held in.

So I guess the original relay just needs a momentary signal to make it latch on, and another to switch if off. RealOEM parts look up shows a 'control unit' at 3 times the price of a standard relay (part no 61356903410 ), so that indicates it is more than a simple relay.

My theory is the original relay is faulty and now only works when latched on by the rocker switch, or it has been swopped out for a standard relay.

Trouble is - I can't find it. I have looked at the various wiring diagrams but none quite exactly match the wire colours on my car. I think the rear fog light relay is K49 (and the front fog lights are relay K47 which is normally in the engine bay fuse box). One of the wiring diagrams shows K49 is located on a relay carrier under the dash, but the wiring colours and relay part numbers don't match my car.

Any help greatly appreciated....

Thanks
Kieran

 

[Althulas]

K49 is in the fuse box passenger side bulk head under the bonnet. Real oem list that as front and rear lamps for my 1998 https://www.realoem.com/bmw/enUS/showparts?id=CK92-EUR---Z3-BMW-Z3 M&diagId=61_4608 but BMW auto parts lists it as the rear fog light relay https://www.bmwautoparts.net/en/catalog/part/61356903410/0/control-unit-rear-fog-light

 

[Nodzed]

The fog switch on my M is a push button switch that stays in when the button is depressed and pops out when pressed again to turn off. Id say your switch is knackered.

 

[farside]

Thanks for the info guys.

Nodzed - I did wonder if the switch that I found was faulty and should latch, so bought another one on ebay. It was the same - non-latching. So, maybe 2 faulty switches. Then I dismantled both completely to check. It is a very simple switch, with no mechanism to be able to latch that I can see. But the fact that your car has a latching switch is interesting, and would solve my problem. I don't suppose you happen to know the part number?

Looking up Real OEM, the switch options listed are:

06	Switch fog lamp and fog tail lamp		1		09/1999	61311387054	$48.12
06	Switch fog lamp and fog tail lamp		1	09/1999		61316901957	$48.12
06	Fog lamp switch		1		09/1999	61311387055	$32.07
06	Fog lamp switch		1	09/1999		61316901958	$32.07

The 2 switches that I have are the parts listed as "Fog lamp switch". I don't know what the difference is to "Switch fog lamp and fog tail lamp" - maybe it's the dual switch for front and rear fogs?

 

[Nodzed]

Thanks for the info guys.

Nodzed - I did wonder if the switch that I found was faulty and should latch, so bought another one on ebay. It was the same - non-latching. So, maybe 2 faulty switches. Then I dismantled both completely to check. It is a very simple switch, with no mechanism to be able to latch that I can see. But the fact that your car has a latching switch is interesting, and would solve my problem. I don't suppose you happen to know the part number?

Looking up Real OEM, the switch options listed are:

06	Switch fog lamp and fog tail lamp		1		09/1999	61311387054	$48.12
06	Switch fog lamp and fog tail lamp		1	09/1999		61316901957	$48.12
06	Fog lamp switch		1		09/1999	61311387055	$32.07
06	Fog lamp switch		1	09/1999		61316901958	$32.07

The 2 switches that I have are the parts listed as "Fog lamp switch". I don't know what the difference is to "Switch fog lamp and fog tail lamp" - maybe it's the dual switch for front and rear fogs?

Agree the top two are probably for non M's with dual fog lights, so 055 & 958 are probably the single switch for just rears, absolutely no idea what the difference between the two singles are though

 

[Nodzed]

Fog Light buttons

Hi there, I was innocently pushing a few buttons over the weekend and generally getting a feel for my Z3. When I pushed the rear fig light switch it decided it didn't want to switch off. Can anyone give me some advice on what I could do to release the button. Or where I could find a...

zroadster.org

Have a gander and this, could be both switches are just gummed up?

 

[farside]

It’s a good thought, but no, switch has been completely dismantled and reassembled, all working smoothly.
The switch is simple enough, as you can see from the picture, there’s not much to it.
I think I’ll try to find a latching button version like yours as that would seem to be a simple fix.

 

[Nodzed]

It’s a good thought, but no, switch has been completely dismantled and reassembled, all working smoothly.
The switch is simple enough, as you can see from the picture, there’s not much to it.
I think I’ll try to find a latching button version like yours as that would seem to be a simple fix.

View attachment 177621

Well I would say looking at the terminals that is clearly a latching switch, designed to remain in contact to bridge the terminals. The bridge part is, I would say, broken/failed internally. I can find no other switch type option.

 

[farside]

Hi Nodzed
thought you might be interested to know - sourced a new switch at a fairly reasonable £20 from BMMINIPARTS (dealer was £40), and it is a latching switch, by means of a stiff piece of wire which slides along the side of the plastic plunger body. No idea why it would be missing from both switches that I have.

Anyway, all sorted now, thanks to you and Althulas for responding.