CEM-1E04 Lamp Switch Module

[Wentworth]

Hi All,

I hope someone can help with the following issue that's come up on my 2002 V70.

Symptoms:
=========
Light Control switch no longer operates the headlamps, fog lights, rheostat or headlamp levelling. Main beam flashes only (as if lights are set to pos 0).

Backlit LCD displays in car (e.g DIM readouts for gear, mileage etc) and Radio are all very dim.

Just to add to the fun/confusion:
=========================
I have driven the car over a rough road and the LCD display lights will brighten again and may stay on until the ignition is switched off then on again. This does not always happen over bumpy roads though.

I recently removed and recharged the battery (thinking that it could be voltage related) and the displays and Lamp Switch worked as normal.... for a single drive, then back to the above.

I have read the codes on the car:
=========================

Codes are:

CCM0021 - Air Quality Sensor
CEM1E04 - Communication with LSM control module Signal missing
PDM0025 - Mirror motor signal missing
UEM0004 - Siren Communication fault

VIDA states that the likely causes of CEM-1E04 are a faulty Lamp Switch Module, or a circuit fault between the LSM and the CEM.

I have swapped out the LSM for a working 2nd hand unit, no change.

Has anyone come across this before and can you give me any pointers before I start pulling things apart to get to the wiring between the LSM and the CEM?

I have searched the forums and can't find reference to this error code above. I would guess that a faulty indicator/beam flash stalk would throw a different code and in all descriptions of this problem no mention is made of the lamp switch being dead. In fact as we know its usually the case that the lamp switch has been set to the 3 o'clock position and so won't hold main beam.

The only other clue I have, bearing in mind that all the backlights are very dim is that maybe the light sensor is dying. This was mentioned in post 9 of the attached query about light functions, but the user is no longer active, so I can't check...

http://www.volvoforums.org.uk/showth...ht=Lamp+Switch

This is the relevant bit:

"So my 04 S60 D5 encountered a similar problem; unable to engage full beam and the cockpit light display was very dim.

Volvo dealer replaced the light sensor and the main-beam switch/sensor thing under the warranty - no questions asked."

I'm wondering whether a failing light sensor could affect the light circuit.... VIDA says:

"If the nightfall sensor is covered, the climate control module (CCM) does not receive any signals regarding light intensity, and the brightness of the LED buttons cannot be regulated"

So, maybe this could explain the backlights being dim, but I can't find any connection to this preventing the CEM from reading the LSM?

Thanks for reading this far... any help or supportive comments would be greatly appreciated.

Cheers,
Paul.

[Clan]

i would say the CEM cant read the Light switch module , which has only 3 wires , a live feed , an earth and the LIN communication wire , To test the LIN get a LED in series with a 500 ohm resistor and connect it between earth and the LIN wire , you should see very fast flashes if there is data on the line , also check volts on the LIN should be somewhere less than 12 depending on how much data is going along it , say 9 volts . + or - a bit . check the power feed to the light switch and check the earth wire . If you are sure your second hand light switch is good , then run a new LIN wire from light switch to CEM to prove a point , still failing then a faulty CEM ..

[Wentworth]

Thanks Clan, much appreciated.

Cheers
Paul

[DeeJay]

This is spooky! For a few months now I have had , and still have, an almost identical problem on my 2000 plate V70.

It started late last year the day after a longish drive in very heavy rain and wet conditions. Started the car in the morning, everthing dark pretty much as Wentworth described then, as if by magic, after driving for about ten minutes, everything came back.

Since then, it comes and goes although my initial thoughts that it may be related to wet weather driving are now not so sure.

What I have which Wentworth doesn't describe is that when all the lights come back on, including the light switch, that unit will "go out" after a few minutes with no control of any of its functions leaving the remainder of the lights on.

Another deviation I have is that when starting the car first thing after it's been standing for a while, overnight, at work or been parked shopping (groan!) , all those lights will brighten up after about ten seconds if they are all on, or if the dash binnacle is black, then they come on at dim.

Wentworth, I'll be interested to know if/when you achieve a resolution if you don't mind sharing with an old geezer!

[Wentworth]

So glad i'm not alone!

I also has some mixed combinations of lights etc, but now all dim all the time. I am hoping to get out and take a look at the wiring if the rain ever stops!

I will post back if i get to the bottom of this.

Cheers
Paul.

[DeeJay]

Saturday very wet, lights off then on at various times through the day, but always in the sequence off after being parked, then on at some time.

Sunday dry, off and on a couple of times then on for the last trip of the day.

Yesterday (Monday) dry, all on at first start in the morning, same again when leaving work late p.m. Out again in the evening for trip to supermarket, about 4 miles away, all on....but!!...the external temperature was showing minus 12 without the snowflake symbol being lit!! Jeez! Cold enough to freeze the nutz off a brass elephant, but local population of said elephants not trumpeting in squeaky voices so deduced not that cold! During drive to shop, temp increased gradually, snowflake lit up at minus 6, when I reached the s/m, temp at plus 2 with snowflake on.

In the shop about 15 minutes, started up, all lights on with temp showing plus 7.

I think I'm getting more closely observant as this condition progresses as I noticed this morning that petrol was indicating just above the red mark and as my commute progressed, the gauge rose gradually to reach the first dividion on the gauge which is where I expect it to be.

I mention the weather conditions as I still have a niggle in my mind this problem seems to be related to wet/damp.

[Rainbird]

With it being damp related, it could be a dodgy earth somewhere or a corroding connection. As these get warm with current flow or dry out, then the resistance drops and things work better

[DeeJay]

Even though mine is almost identical to Wentworth's situation that has been in the back of my mind Rainbird. I purchased the car around May last year and it was mostly dry, and had no issues until the first time I drove in that very heavy rain I mentioned earlier.

I might get a chance to see if that is the case today as the rain has started in again.

I've looked at Mr Haynes "typical" wiring diagrams which are about as much use as an ashtray on a motorbike! One thing I keep seeing however, is a "canbus" which I presume is similar to a busbar in normal electrics.

I'll keep this update going.

Cheers!

[nickbw898]

Originally Posted by DeeJay

Even though mine is almost identical to Wentworth's situation that has been in the back of my mind Rainbird. I purchased the car around May last year and it was mostly dry, and had no issues until the first time I drove in that very heavy rain I mentioned earlier.

I might get a chance to see if that is the case today as the rain has started in again.

I've looked at Mr Haynes "typical" wiring diagrams which are about as much use as an ashtray on a motorbike! One thing I keep seeing however, is a "canbus" which I presume is similar to a busbar in normal electrics.

I'll keep this update going.

Cheers!

Take a look at this link for an explanation of canbus
https://en.wikipedia.org/wiki/CAN_bus

What year and model do you have? I will try to post a link for a proper Volvo wiring diagramme in PDF format. - I cannot do so now as am on a windows laptop -the documents needed are on my home iMac.

[Chris_Rogers]

Originally Posted by DeeJay

Even though mine is almost identical to Wentworth's situation that has been in the back of my mind Rainbird. I purchased the car around May last year and it was mostly dry, and had no issues until the first time I drove in that very heavy rain I mentioned earlier.

I might get a chance to see if that is the case today as the rain has started in again.

I've looked at Mr Haynes "typical" wiring diagrams which are about as much use as an ashtray on a motorbike! One thing I keep seeing however, is a "canbus" which I presume is similar to a busbar in normal electrics.

I'll keep this update going.


Cheers!

Proper diagrams here:

http://www.volvowiringdiagrams.com/?dir=