Phantom Warnings

[Cheltenhamshire]

Any help would be appreciated on this one.

I have a case of phantom warnings on my car. It is a 2003 C200k Sport Coupe. It has done 31,000 miles and it has had an attack of the gremlins that should not happen in a Merc....and I used to own Alfa's and even they were not like this!!

1. It has automatic lights. Yet, on a cold or frosty day tells me the sensor is broken but switches the lights on anyway! Microsoft style turn the ignition off and then on again 'fixes' the problem. I think it is actually frost over the sensor that actually causes the problem, can anyone confirm this?

2. Alternator failure.....car bleeps at me in red. I stop, turn off and on again and gone. Never happended since.

3. Rear brake light bulb blew. I replaced it and 2 weeks later it blows again, except when I go to replace the bulb it had not blown. Switch off and on still says the bulb has gone. Bulb has not gone!! Try again this morning...nothing at all.

The car is out of warranty in 2 weeks, I am tempted to book in and get them to just check it all out, worthwhile??

 

[steve kane]

I would think its worth getting it in quick for a check under warranty just in case, I have to say that as a home mechanic its the electrics on modern cars that worry me and from my limited experience of Garages they are as bamboozeled as I am most of the time, it does not bode well for those of us running older cars in the future I fear.
Steve.

 

[robbo]

Its most likely low voltage on your battery. All sorts of strange warnings come up when the battery is on its last legs.Try a new battery, 10:1 it'll solve all the gremlins.

Word of warning. Dont do it yourself to save a few quid, get the dealer to do it. The rear SAM unit on the C class has a habit of failing when the battery is reconnected. That'll cost you around £500 to fix.

 

[Cheltenhamshire]

Should a battery really be on its last legs after just 3 years and 31,000 miles? That seems a bit daft to me, I know batterys do more these days than back in the 70's & 80's but battery technology has also moved on to give more power etc and reliability.

There has been no issues with starting, running etc and the dealer never said anything at either the recent service A and mot or the service B of last September.

 

[television]

Most batteries do last 5 years on average. do you have a volt meter.if so test before you start the car. If you have to drive somewhere to test, after you stop the engine , turn headlights on and leave for 5 mins, and test with lights on.

Malcolm

 

[robbo]

That seems a bit daft to me.

well its up to you whether you take my advice or not. I'm not fussed either way.

When the battery voltage is low, all sorts of random faults show up. The car can start and drive fine. It wouldnt be unheard of for three year old cars to have battery faults. I personally know people who have had this problem.

when the faults next occur, take it to the dealers and ask them to check the battery voltage.

 

[Cheltenhamshire]

Robbo, chill mate! I am not criticising you when I said it sounded daft....it is just that I have never heard of that happening before, it is the kind of thing you hear when describing an old banger!!!

I have the car booked into the dealer for Saturday but I will ask them to check that as well, the car is on its last 2.5 weeks of warranty. The brake light said it had blown again today, so 3 days on the trot...and of course it is fine!

I will let you know what the dealer bods say on Saturday.

 

[jonnyb1]

Hi, must agree with robbo.my battery seemed ok .started fine etc but no cruise no rear wipers......... changed battery on advice and cruise and rear wipers returned.....so there you go cheers

 

[robbo]

Robbo, chill mate! I am not criticising you when I said it sounded daft..

No worries, long day at work and all that

 

[SJMaxson]

Me too?

I'm interested in this, as I was going to mention an intermittent rogue warning when my service next falls due.

Four or five times I have had a warning "Check left brake light", only to find that the bulb is working fine. Every time I restarted the car for the subsequent journey, the fault had cleared.

On one occasion, the bulb seemed to have failed, but the same bulb came back on on the way to Halfords, and has been working fine for the last two months!

Isn't there some kind of issue relating to batteries in C classes (as it is in the C class that I am having the problem)?

 

[television]

Talking about batteries, they are no different to any other piece of the car, that is though everything was fine when it left the factory things break down. When the battery is going down normally you can tell by the way the car starts. batteries cost little more than the oil and oil filter, yet so many people wait till the AA has to be called to start the car. those that leave it too late risk the damage caused by incorrect jump or boost starting. A meter to test the battery can be bought for £4 (digital) When first thing in the morning its under 12volt then the time has come to replace it. If no boost or jump starting has taken place, one can plug a battery back up in the cigar lighter and change the battery, No steering angle to be reset no anything other than peace of mind know that the car will start during those cold mornings. Always fit a premium brands, no house specials.
Don't forget too that your starter motor over heats the field coils with a bad battery as the cranking speed is reduced.

Malcolm

 

[Cheltenhamshire]

Okay, I have just got back from Country Merc (authorised Merc service centre) and they ran my car through the computer....and .....

It needs a new alternator (this one is over-charging)
It needs a new 'SAM' (which is some kind of module that controls electrics at the back of the car)
It needs a new light sensor

Lucky this will all be paid for by warranty....holy crapola...the bill would have been over a grand otherwise!!

So in the 1 year I have had my Merc it has had more electrical and electronic problems than my previous 3 italian cars (2 Fiats and 1 Alfa) over a combined period of 6 years.

Incidentally the battery is fine!

As it goes out of warranty next month....the part ex against a Honda / Mazda / Skoda is becoming much more attractive.

 

[CLK Man]

Robbo, does this SAM unit (whatever it is) apply to CLKs? I get the odd message - mainly about BAS - but was thinking it was battery, going to change itself myself, but now wary of damaging anything.

It's not a dealer job is it - changing batteries on mercs, surely?

Regards,

CLK Man

 

[robbo]

Don't know about CLKs, but the SAM module on the C class is reputed to be prone to failures. I have heard of a number of SAM failures occuring when the battery is reconnected. Put it this way, when my battery finally gives up (its on its way out now) it will be getting replaced at the dealers.

 

[robbo]

It needs a new alternator (this one is over-charging)
It needs a new 'SAM' (which is some kind of module that controls electrics at the back of the car)
It needs a new light sensor

Good news about the warranty. let's hope that replacing all these parts at vast expense solves the problems. It wouldnt be the first time if it didnt.

 

[Cheltenhamshire]

Well I hope so too Robbo....because if not then this will have been my first and last Merc.

I can't be bothered to put up with such crap reliability from an otherwise very nice car....