Lamp Defective error (rear fog light)
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Junior Member
Joined: Apr 2014
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CLK230 W208
Lamp Defective error (rear fog light)
I have been having lots of lamp defective error recently:
1. Error when high beam/flasher turned on. Fixed by changing LED bulb to regular bulb. No error
2. Error when braking. Fixed by replacing my rear brake bulb.
3. Error when turning on rear fog light (front fog is fine). I have replaced bulb and seat base but still seems not working. Multi functions light switch still lights on (amber) when turning it on so not sure where problem is.
4. Error when switching my main headlight OFF. Note that switching daytime light off will not cause problem. I cant figure out what might cause the problem.
I think i might read someone says that when headlight switched off, it might related to rear fog lamp.
While I can live without rear fog light, Can somebody please help me out with #4??
1. Error when high beam/flasher turned on. Fixed by changing LED bulb to regular bulb. No error
2. Error when braking. Fixed by replacing my rear brake bulb.
3. Error when turning on rear fog light (front fog is fine). I have replaced bulb and seat base but still seems not working. Multi functions light switch still lights on (amber) when turning it on so not sure where problem is.
4. Error when switching my main headlight OFF. Note that switching daytime light off will not cause problem. I cant figure out what might cause the problem.
I think i might read someone says that when headlight switched off, it might related to rear fog lamp.
While I can live without rear fog light, Can somebody please help me out with #4??
Junior Member
Joined: May 2014
Posts: 20
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From: Hampshire, UK
Mercedes CLK 320 (W208), '73 Chevy Nova
Fixing 3 may remedy 4, so it's probably worth doing that and having working lights all round.
If the fog lamp is not coming on at all, it would be worth testing the metal base (where you screw in the lamp holder) with a volt meter to see if you have 12v. If not, check the other side as only one side seems to be function (I intend to wire up both sides to work as I like the symmetry). Anyway, that's the first thing to do, make sure you have power there. I'll post up a pic when I take a break and can get to the car.
With regards to 1, you can get LED lamps that are CANBUS approved, and they will work. However, unless you buy and expensive LED lamp, the brightness will be a lot lower than the conventional incandescent lamp. It's always wise to check that the output of the LED in lumens is comparable to the lamp that you are replacing.
If the fog lamp is not coming on at all, it would be worth testing the metal base (where you screw in the lamp holder) with a volt meter to see if you have 12v. If not, check the other side as only one side seems to be function (I intend to wire up both sides to work as I like the symmetry). Anyway, that's the first thing to do, make sure you have power there. I'll post up a pic when I take a break and can get to the car.
With regards to 1, you can get LED lamps that are CANBUS approved, and they will work. However, unless you buy and expensive LED lamp, the brightness will be a lot lower than the conventional incandescent lamp. It's always wise to check that the output of the LED in lumens is comparable to the lamp that you are replacing.
Thread Starter
Junior Member
Joined: Apr 2014
Posts: 51
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CLK230 W208
Thanks Darren,
Yes, I use "el Cheapo" non Canbus LED for high beam but have switched them to 6000K halogen. My daytime LED is canbus so no error on that. You are right, in order to use LED as main beam, you have to use very high quality or better off with halogen if cant afford xenon. I use Xenon as low beam and will stick with 6000K halogen for high beam for now.
Back to #3, Yes I think I should be working on the right side because passenger side rear fog lamp housing doesn't even have seat/bulb on it. Please bear in mind that the error only appear when main headlight (low/high beam) switched off or turned to daytime light. Turning daytime light to off does not generate error.
I have never seen rear fog light work since I bought the car but I also have no check bulb error when turning rear fog light on or when switch off main beam until recently.
Yes, I use "el Cheapo" non Canbus LED for high beam but have switched them to 6000K halogen. My daytime LED is canbus so no error on that. You are right, in order to use LED as main beam, you have to use very high quality or better off with halogen if cant afford xenon. I use Xenon as low beam and will stick with 6000K halogen for high beam for now.
Back to #3, Yes I think I should be working on the right side because passenger side rear fog lamp housing doesn't even have seat/bulb on it. Please bear in mind that the error only appear when main headlight (low/high beam) switched off or turned to daytime light. Turning daytime light to off does not generate error.
I have never seen rear fog light work since I bought the car but I also have no check bulb error when turning rear fog light on or when switch off main beam until recently.
Junior Member
Joined: May 2014
Posts: 20
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From: Hampshire, UK
Mercedes CLK 320 (W208), '73 Chevy Nova
That's likely because the fog will only operate when main or dipped headlights are on, they won't work with only sidelights/running lights on.
If you put a voltmeter between terminal 1 and terminal 2 with the ignition on, dipped headlights on, and fogs on, it should read around 12v (or -12v if the + and - are on the wrong terminal).
If you haven't got power there, then you'll need to start looking at the wiring and tracing it back, or have a look at the switch to make sure that the problem isn't that end. If you do have power there, the problem is in the lamp or lamp holder, possibly not making a good contact.
If you put a voltmeter between terminal 1 and terminal 2 with the ignition on, dipped headlights on, and fogs on, it should read around 12v (or -12v if the + and - are on the wrong terminal).
If you haven't got power there, then you'll need to start looking at the wiring and tracing it back, or have a look at the switch to make sure that the problem isn't that end. If you do have power there, the problem is in the lamp or lamp holder, possibly not making a good contact.
