Low beam lights not working

[blompa]

Hi,

So my low beams stopped working out of the blue. My volvo is a 2001 2.4T with halogen lights. The high beams work just fine.
I've checked the three fuses in the car. They are all ok. I've switched out the relay and the shunt. Which I think was unecessary.

I measured the voltage over pin 1 and 3 on the relay on the CEM. That showed 12v+ when the lights were supposed to be on.

I measured the voltage at the light end and it shows 45mV.
I then measured pins 2 and 3 on the shunt and that shows 45mV too...

When I switch the lights off the voltage goes down to 0v as it should

what could cause the shunt and the lights to only have 45mV?

[yagger]

Can you change of brightness of back-lights on your cluster (DIM)?

[blompa]

Can you change of brightness of back-lights on your cluster (DIM)?

Hi,

I can regulate the lights up and down but interior DIM wheel does nothing!
Is it as simple as replacing the LSM?

[Varieze]

yagger,

Could you please contact me. I am a new member and cannot PM yet. Have 09 S80 with
used replacement SRS module that needs to be cloned to original module.

Varieze[*]

[yagger]

Can you change of brightness of back-lights on your cluster (DIM)?

Hi,

I can regulate the lights up and down but interior DIM wheel does nothing!
Is it as simple as replacing the LSM?

A bit confused...
DIM - Driver Information Module (this is a cluster)
Can you regulate of brittleness of back-lights for it?

[blompa]

Hi, I apologize forv the confusing reply.

The LSM has two wheels. The one controlling exterior light angle works.

The one that controls interior light brightness does not work.

Does this mean that the LSM is at fault?

[yagger]

Looks like yes. )

[blompa]

Hi again

I tested with another LSM that had a working brightness wheel. Same problem!

It appears I made a mistake when looking at the my original brightness setting. It does work after all so the problem is then outside of the LSM?

[yagger]

Ok. In this case check power on fuses numbers 4, 10 and 11 on the fusebox located left from steering wheel.

[blompa]

@yagger is my summary below at all useful?
Thank you so much for your time and effort!

My apologies. I can rebuild engines, I can tune trim cams but I cannot check the right damn bulb

It is sorted now and my lights work just fine!

Here's what I learned at least.

1. Check the lamp. Measure it for resistance using a multimeter if is unclear.
Lamp ok? go on.
2. if the lamp is ok, then measure voltage at the connect with ignition on 2 and LSM set to auto.
0v? go on
3. check fuses 1 & 2 (11C/1 and 11C/2) (in the car)
Both fuses ok? go on
4. Measure the voltage at the fuse? (each point on the fuse against ground)
0v? go on.
5. Measure the shunt on the CEM. Measure the middle pin against ground.
0v?
6. Test that the shunt is not broken between pins 2 and 3. (if it is, test with another shunt on the CEM. Make sure they have the same parts number)
It is complete,
7. measure the the connection between the relay pin #1 and shunt #3. (if this is Not ok then the CEM or the pins are bad)
Looks ok: Go on
8. Test the relay on the CEM, swap it for another and see if it clicks when you turn the LSM light switch to parking lights and back. (Other things to note: The voltage should be 12v over pins 1 and 3 on the relay when lights are on. If the voltage is +12v here then the LSM is most likely also correct)
It clicks, and seems fine.
9. Measure the (11C/3) fuse and check that it is ok and its pins has 12v against ground
fuse is ok and 0v?
Not sure what else to test if you reach this point and everything is ok.

on a sidenote: You can make sure it is not the LSM light switch module by testing whether the brightness wheel changes brightness on your dashboard back lights