Electrics: Main beam issues

[a993lad]

I have this problem too. No beam, no beam indicator no headlight flash.

Light switch is vertical (on)

My car is 2006

Does anyone know if it would have a relay for main beam?

Dip beam, all fuses and bulbs are okay

[Clan]

Originally Posted by a993lad

I have this problem too. No beam, no beam indicator no headlight flash.

Light switch is vertical (on)

My car is 2006

Does anyone know if it would have a relay for main beam?

Dip beam, all fuses and bulbs are okay

No there is no relay , the headlamps are driven directly by the Central Electronic Module , the main computer ( CEM ) , fuses F22 and F23 drive the main beams , these fuses are in the CEM abover the accelerator pedal , are these fuses live with the headlamp switch on?

Sounds like water may be getting in the CEM which is possible on a 2005 and 2006 ...

[a993lad]

Originally Posted by Clan

No there is no relay , the headlamps are driven directly by the Central Electronic Module , the main computer ( CEM ) , fuses F22 and F23 drive the main beams , these fuses are in the CEM abover the accelerator pedal , are these fuses live with the headlamp switch on?

Sounds like water may be getting in the CEM which is possible on a 2005 and 2006 ...

Thanks. I've now removed the panel and found the cem. All the fuses seem okay but don't seem to be numbered so can't easily identify f22 f23. I'm guessing they are the 10amp ones about half way along the bottom row (6th and 7th along counting from the left)?

[a993lad]

Originally Posted by a993lad

Thanks. I've now removed the panel and found the cem. All the fuses seem okay but don't seem to be numbered so can't easily identify f22 f23. I'm guessing they are the 10amp ones about half way along the bottom row (6th and 7th along counting from the left)?

I have now located fuses 22 and 23 tested both and the fuses are fine but there is no power coming to those fuses though. So to recap the engine is running the lights are switched on the dipped beam is working okay but the main beam is not. Both of the headlight fuses under the Bonnet in the Main fuse box are fine.

There is definitely power at the CEM because I tested a couple of other fuses and they were receiving power. But f22 and f23 are not live when the lights are switched on. Do they become live all the time headlights are on or only once you switched on the full beam?

[Clan]

Originally Posted by a993lad

I have now located fuses 22 and 23 tested both and the fuses are fine but there is no power coming to those fuses though. So to recap the engine is running the lights are switched on the dipped beam is working okay but the main beam is not. Both of the headlight fuses under the Bonnet in the Main fuse box are fine.

There is definitely power at the CEM because I tested a couple of other fuses and they were receiving power. But f22 and f23 are not live when the lights are switched on. Do they become live all the time headlights are on or only once you switched on the full beam?

fuse 22 and 23 are in the bottom row of small fuses bottom right is fuse 30 so count back along to the left ..

The 2 fuses will be live when the headlamps are on main beam only ..

check the fuse INPUTS to the CEM , ( it is in the fuse box by the side of the battery , you will have to take battery out to check , they are in a row of 7 bolt on fuses .. fuse 5 the middle one..
But if this was blown a lot more circuits wouldnt be working ..

Failing all that you need to get it to the dealer so they can see if the signal from the stalk is getting to the CEM to turn main beams on . If it IS , then a new CEM will be required and the waterproofing kit fitted if this is the cause ..

[a993lad]

Originally Posted by Clan

fuse 22 and 23 are in the bottom row of small fuses bottom right is fuse 30 so count back along to the left ..

The 2 fuses will be live when the headlamps are on main beam only ..

check the fuse INPUTS to the CEM , ( it is in the fuse box by the side of the battery , you will have to take battery out to check , they are in a row of 7 bolt on fuses .. fuse 5 the middle one..
But if this was blown a lot more circuits wouldnt be working ..

Failing all that you need to get it to the dealer so they can see if the signal from the stalk is getting to the CEM to turn main beams on . If it IS , then a new CEM will be required and the waterproofing kit fitted if this is the cause ..

Okay thanks this is really helpful and much appreciated.

So I guess it's not surprising that the fuses in the CEM are not live because I can't switch the headlights on to main beam.

Also from what you are saying it can't be the fuse under the battery because everything else is working on the car except the main beam as far as I'm aware. Out of interest do you know what other functions would fail if it was the Main fuse under the battery?

Do you know how they check if the signal from the stalk is reaching the CEM?

Is failure of the main beam lights a common symptom of water getting into the CEM? I have read a few posts now about CEM failure due to water and it seems to cause far more serious issues than just the main beam lights packing up - such as all the electrics failing, windows, air conditioning etc and the engine stopping.

Thanks again

Marc

[Clan]

Originally Posted by a993lad

Okay thanks this is really helpful and much appreciated.

So I guess it's not surprising that the fuses in the CEM are not live because I can't switch the headlights on to main beam.

Yes the fuses are on the output of the CEM so only live when main beam is on ..

Also from what you are saying it can't be the fuse under the battery because everything else is working on the car except the main beam as far as I'm aware. Out of interest do you know what other functions would fail if it was the Main fuse under the battery?

Do you know how they check if the signal from the stalk is reaching the CEM?

They check the input signal for main beam from the stalk to the CEM via VIDA , it is send down the network as a digital signal ..

Is failure of the main beam lights a common symptom of water getting into the CEM?

No it isnt actually , stop lights are affected sometimes though ...


I have read a few posts now about CEM failure due to water and it seems to cause far more serious issues than just the main beam lights packing up - such as all the electrics failing, windows, air conditioning etc and the engine stopping.

Thanks again

Marc

I would get it diagnosed first , or if you are feeling like it get the CEM out and take the covers off and look for corrosion on the plug pins and circuit board .. simply a clean with a wet toothbrush may do it , or you might get it repaired ...

[a993lad]

Thanks again clan.

I have found a replacement indicator/ light stalk on eBay so I have bought that and I will swap it out to see if it is the switch in the stalk.

That doesn't solve the problem then I guess I am off down the dealers to get it diagnosed.

Marc

[Chilly]

A while ago I had problem with the indicator on our car. It did not work on the right side. No fault codes where set. The local volvo garage wanted to change the streering wheel module. I read about a guy here in swedish forum with a same problem as me. The volvo garage solved his problem after a couple visits and changing parts. The fault was in the wiper stalk. Somehow the error in the wiperstalk disrupted the indicator stalk. So I removed my wiperstalk and voila everything worked. Maybe you could have a similar problem.
//Carl

[a993lad]

Originally Posted by Chilly

A while ago I had problem with the indicator on our car. It did not work on the right side. No fault codes where set. The local volvo garage wanted to change the streering wheel module. I read about a guy here in swedish forum with a same problem as me. The volvo garage solved his problem after a couple visits and changing parts. The fault was in the wiper stalk. Somehow the error in the wiperstalk disrupted the indicator stalk. So I removed my wiperstalk and voila everything worked. Maybe you could have a similar problem.
//Carl

Thanks chilly. I just removed my wiper stalk but the beam lights still won't switch on. Just wanted to check if you really meant "remove" the wiper stalk rather than "replace" it.