fog lights

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Neilz3
Joined: Fri 26 Jul, 2019 23:03
Posts: 6

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fog lights

Post by Neilz3 » Sun 29 Sep, 2019 20:53

Hi,
I have got my first z3 and have been fixing some issues with the car, but have a problem I cannot currently fix.
When I got the car the front fog lights are permanently on when my head lights are on. I have disconnected the bulbs so i am not driving with them on.
I have checked the relay to ensure it is not stuck, swapped with horn relay and no issues as horn works fine with fog relay. I pulled the fog switch out of the block and both show on the dash. I have took the switch apart and cleaned with no success. Is there a way to bypass the block to switch on and off to prove out if it is a switch issue.
Or is there any other checks I should doing? :head:

LaRy
Joined: Mon 12 Nov, 2018 17:47
Posts: 50

  Z3 roadster 2.8

Re: fog lights

Post by LaRy » Mon 30 Sep, 2019 08:48

Hi, my information is valid for a Z3 -98.

Here you have an electrical drawing: https://i.imgur.com/5nOYjZI.jpg

I would actually test what happens without relay an what happens with the fuse F15 removed.
So, if the headlight is off, the fog light is also off, correct?

That test will decide if we continue to check the control circuit or the main circuit.

One test you could do is actually to take out the fog light relay and check if you have voltage at relay socket, pin 86.

Neilz3
Joined: Fri 26 Jul, 2019 23:03
Posts: 6

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Re: fog lights

Post by Neilz3 » Mon 30 Sep, 2019 16:59

Thanks, will try that tomorrow when it is dry.
You are correct when the lights are off the fog lights are off.When lights on, lights and fog light on and green fog light shows on instrument cluster.
I will remove the relay and see what happen and the f15 and report back.
I will also check pin 86 for voltage. fingers crossed. :)

LaRy
Joined: Mon 12 Nov, 2018 17:47
Posts: 50

  Z3 roadster 2.8

Re: fog lights

Post by LaRy » Mon 30 Sep, 2019 21:49

You have been writing about the fog light switch, but I want to know if you actually can switch on / off the fog light by connecting /disconnecting the fog light switch.
You have cleaned the switch, but have you made any actual electrical test of the function.

Neilz3
Joined: Fri 26 Jul, 2019 23:03
Posts: 6

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Re: fog lights

Post by Neilz3 » Tue 01 Oct, 2019 20:36

Hi,
When I disconnect the switch, front and rear illuminate on the dash. (not checked lights as I have to re-connect)
I have checked the switch for continuity.
Both seam to work the same, button in- continuity, button out no contact. (1-2 pin, 3-4 pin)
Rear works fine on / off.
Front permanently on.
Not been able to get on the car today as finished work late.

Neilz3
Joined: Fri 26 Jul, 2019 23:03
Posts: 6

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Re: fog lights

Post by Neilz3 » Wed 02 Oct, 2019 19:40

Update,

I have remove the fuse, fog light went out and dash light went out.
Put fuse back and the tried relay, relay removed, no fog light and no dash light.
Main lights worked as normal.
I check the relay locations on the fuse board, 87 and 30 had power. No power, 85-86-87b.

What I did notice is rear fog - button in the rear fogs on, to turn off push button in, it pops out, but this needs to be done twice to turn off.
(is this normal?)
All ideas welcome.

LaRy
Joined: Mon 12 Nov, 2018 17:47
Posts: 50

  Z3 roadster 2.8

Re: fog lights

Post by LaRy » Wed 02 Oct, 2019 21:46

Hi, the rear fog light button should be released by one press.
So you have power on 30 one the fuse board, with removed relay, that is slightly odd. I assume this is meassured with installed fog light bulbs.
What happens if you just remove the connections to the switch?

Neilz3
Joined: Fri 26 Jul, 2019 23:03
Posts: 6

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Re: fog lights

Post by Neilz3 » Thu 03 Oct, 2019 18:17

hi,
When checking relay for power, this is with everything else connected as it should be.
If I remove the switch, main lights on, the front fog lights are on and on the dash.
The rear fog is off and off on the dash when switch is removed.
:shake:

Neilz3
Joined: Fri 26 Jul, 2019 23:03
Posts: 6

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Re: fog lights

Post by Neilz3 » Thu 03 Oct, 2019 18:27

I read the drawing as have permanent live at pin 30.

LaRy
Joined: Mon 12 Nov, 2018 17:47
Posts: 50

  Z3 roadster 2.8

Re: fog lights

Post by LaRy » Sat 05 Oct, 2019 08:48

pin 30 should be live all the time.
We know if you take the relay out, fog light is off.
We know if you take fuse F15 out, fog light is off.
We also know, that the head light must be on, making the fog light on, independent of if the fog light switch is assembled or not.
That means that somewhere, from the output of the head light switch, the relay will get control power. You have to open the cable harness and look for bad insulation. Remember that it can actually also be in connection to the wires putting on the head lights, from the head light circuit.
I would start at the yellow/green wire between the relay and fog light switch, as close as possible to the relay, follow it all the way up to the fog light switch. This wire should go straight between the switch and relay. maybe have to split the cable harness, to follow the wire.
Sometimes, in trouble shooting, it could even be a solution to temporarily cut this yellow/green wire "in the middle", just to check if fog light is still on. Cut it between the torpedo wall, to see if the unwanted feed of power to the relay is from the engine bay area or the dash board area.

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