Crazy headlight switch 2001 V70 2.4T

Draaz · Post by **Draaz** » 10 May 2012, 19:39

So I am the proud owner of a used Volvo, my first one. It is a 2001 V70 2.4T and I love it except for one minor issue. the headlight switch is bipolar or schizo one. Sometimes the switch works and I can use my high beams, other times it is just the Day Time running lights and such. Time of day, weather, bumpy roads, it is purely random. I am hoping someone has heard of this and knows a solution. I have gone over the entire car for fuses and relays and everyone of them check out. Any assistance on this problem would be greatly appreciated.

Skip Isaacs
2001 V70 2.4T

Post by **steve850** » 10 May 2012, 23:18

This is a US model, i take it?

Post by **jimmy57** » 11 May 2012, 08:16

The light switch is a module connected to the CEM, it is called the light switch module, LSM.
There may be codes related to it or communication with it in the CEM. The issue could be LSM or the CEM.
If the problem happens regularly then it will not be hard to find. If it is infrequent then it is much harder as it may check out all OK when things are being checked.
To start you could unplug the LSM and see if the irregular behavior happens when the LSM isn't connected. If it does then the wiring to CEM or the CEM are the things to check.

Draaz · Post by **Draaz** » 03 Jun 2012, 20:21

Steve in Montreal.... Yes it is a US model.

Jimmy57....... Thanks for the info. At least it is a place to start. I appreciate the info very much. I will reply if I find anything out.

Skip Isaacs
2001 V70 2.4T

keithatcpt · Post by **keithatcpt** » 06 Jun 2012, 09:31

My us-model S40 has daytime running lights, so the lights are on anytime the engine is on. The light switch seems redundant except if I want parking lights only. But, if you leave the light switch in the "off" position, the high-beams don't work. This is a feature, not a bug. If you turn the switch to the "headlights on" position, the high beams work and the lights still turn off when I shut the engine off. Is it as simple as that? Maybe your headlight switch is flaky, making the computer think that the switch is in the off position intermittently?

Post by **steve850** » 09 Jun 2012, 12:43

Operation is as keith said, but some years there were differences on canadian and us models. In 96 (and maybe later) there was a small screw next to the switch to disable the DRL's. This option was not available in Canada as we've had mandatory DRL's for years... I doubt you have the little screw, but it would be to the bottom right of the switch.

Post by **jimmy57** » 09 Jun 2012, 15:41

Software replaced the little screw and the light switch is not a switch. It is a unit that sends via a digital signal to the CEM, the inputs you have requested by your turning of the knob, rolling of the light level control, and depressing of fog light buttons.

itllbemethen · Post by **itllbemethen** » 12 Jul 2012, 10:56

I maybe able to "throw some light" on this !

....and the previous writer provides the answer and the reason.

When is a switch not a switch ? When it's a module !

Had the very same problem with my V70. The "crazy" switch problem.
No main beam, always the same lighting configured, regardless of switch selection, no fog lights...oddly no centre consule radio/cd illumination either !

Then I found this.....

Hi,

I have some electrical gremlins with my 2000 (new shape) v70 - I am hoping that someone may be able to help track down whether it is the DIM or CEM I need to take out and fix!

Symptoms are:

-Start engine and instrument panel illumination stays off for several seconds before coming on (warning lights work as normal)

-Radio / CD player works but no display or backlights to controls

-Controls for climate control switches very dim

-No backlights on auto gear selector

-Instrument panel clock, odometer and message display very dim, but appears to work OK

-Headlight switch does nothing and appears to have no power - the daylight running lights are always on whether you select sidelights or night running and the main beam wont stay on in any setting.

The car runs and drives fine otherwise with no messages or warning lights.

From my search of the forum I suspect the DIM or CEM, but before I tear the car apart, which should I target first!?

At first I thought I'd written it myself !!!! Or he's stolem my car !

The answer he got was virtually a "one liner"

"Sounds like the light switch module !

We'll there ya go !

BillyBob · Post by **BillyBob** » 18 Dec 2012, 09:12

Can this be replaced by average Joe driver? If so, how??

thank you!

Post by **packetfire** » 01 Jul 2013, 20:14

I assume that the switch modules have been replaced by now, but for the record, one opens up the fuse access panel at the end of the dash, and one can then push the switch module out from behind. No screws, just a metal spring tab at the bottom of the unit. The single cable detaches easily.