Bulb fail warning light W202

[tonyc280]

Well the bulb fail warning lamp has decided to come on even when my lights are not on. Have checked all around and no bulbs out including reverse and brake lamps. All bulbs are tight in their holders too. Any ideas chappies ?. Cheers, tony.

 

[martyz]

number plate?

 

[tonyc280]

Ahhhh. Didn't check that, cheers, T.

 

[andy27168]

Exactly when does it come on? when you first switch the ignition on? with light switch off? Make sure you are have not got your foot on the brake pedal when you switch the ignition on.
The failure light should only come on when a bulb is switched on and the failure unit then detects it has blown/high resistance in that circuit, from this info you can, by a process of elimination tell which circuit is causing the issue.

 

[PeterE320Cdi]

I had this problem and it was due to a rusty earth. All the lights worked but spotted that one brake light was slightly slower coming on so cleaned up the earth on that side and have not seen the error message since.

 

[tonyc280]

Well chappies have re fitted every bulb and every single one is working and bright but the warning lamp is still on. As i said its on all the time, even when I've not turned my lights on and its not cos i have my foot on the brake. Cheers, Tony.

 

[Dec]

Rear fog lights? on my car there are 2, left and right.

Dec

 

[andy27168]

Rear fog lights? on my car there are 2, left and right.

Dec

Strange Dec, both of mine only had one rear fog (O/S) the factory, just an empty bulb holder in the N/S rear light cluster with an empty pin on the connector presumably where the wire should be if the car was a LHD.
One of the things that you might just want to double check is that you have two rear lights per side at the rear, as a lot of people just see that there is a light working and think its ok and one of them could be out.
I had a reoccurring problem similar to this, I ended up replacing all the rear bulbs with brand new ones (except the number plate ones) and 2 years on touch wood everything been ok since.

 

[tonyc280]

still not sorted. Guess i'll just have to live with it. T.

 

[Dec]

Strange Dec, both of mine only had one rear fog (O/S) the factory, just an empty bulb holder in the N/S rear light cluster with an empty pin on the connector presumably where the wire should be if the car was a LHD.
One of the things that you might just want to double check is that you have two rear lights per side at the rear, as a lot of people just see that there is a light working and think its ok and one of them could be out.
I had a reoccurring problem similar to this, I ended up replacing all the rear bulbs with brand new ones (except the number plate ones) and 2 years on touch wood everything been ok since.

My previous 1994 W202 had one rear fog, my current car has two, I was working on thee assumption that there were changes made since 1994 but now you have me wondering what will happen if I remove the bulb, will the bulb fail warning light come on, will check when it stops raining.

The car passed two NCT tests (Irish MOT) so it cant be illegal.

Dec

 

[balge]

The bulb-failure relay is very sensitive, even a tiny variation in draw between sides can throw it even though the bulbs light up fine, on my 300TD I bought several pairs of new bulbs and juggled them around till the relay was happy...

 

[DSM10000]

Also make sure the bulb holders are bright and have no sign of corrosion on them as this can affect the monitoring circuit.

 

[Dec]

My previous 1994 W202 had one rear fog, my current car has two, I was working on thee assumption that there were changes made since 1994 but now you have me wondering what will happen if I remove the bulb, will the bulb fail warning light come on, will check when it stops raining.

The car passed two NCT tests (Irish MOT) so it cant be illegal.

Dec

The left rear fog light has a dual filament bulb, one filament for fog and one filament for one of 2 tail light bulbs, right side is the same arrangement.

If I remove the bulb then the bulb fail warning light comes on, it all seems to be factory wired, it would be interesting to know if Tony has the same two fog lamp arrangement on the rear of his car?

Dec