Electrical problem?

[Geoff W]

Hi everyone. Just been away for the weekend and yesterday morning started up fine, lowered the electric windows, went about three miles, and noticed no indicators working, tried the electric windows and these were dead too.
Pulled into a garage and switched off to investigate, but found nothing!.
Started up again and everything was as normal? Drove 150 miles today with numerous stops, and no repeat of the problem.
Is this a sign of something failing or should i forget it?
( 1997 C180 Classic.57K.)

 

[jibcl500]

diode pack on your alternator is failing, see if there is a faint battery light showing on the dash in the next few days or weeks.

jib

 

[Geoff W]

Hi. will look out for that, is this a major job, new altenator?
Regards geoff.

 

[anyweb]

if it isn't the above it may be worthwhile checked your over voltage relay protector (OVP), when it goes faulty you may experience some weird electrical issues amongst other things,

cheers
anyweb

 

[Geoff W]

Hi Anyweb, I dont have an OVP relay, I know this for sure as i once had another issue which pointed to this, but mine doesn't have it?
I will just keep running but keep an eye open, the car has behaved perfectly since, Geoff.

 

[jibcl500]

yes you will need an alternator, I bought one second hand off a chap on ebay £40 posted, have a look for SLpagoda on ebay. You can buy the diode pack off a bosch service center and fit them yourself.

jib

 

[bigasotonuk]

Hi,
I don,t mean to question or doubt peoples diagnosis on car faults, but how does indicators and windows not working equate to a 'diode pack' failing in the alternator?
The windows and the indicators run of the battery, not the alternater if the car is starting the battery is ok.

 

[television]

Since the car runs on the alternator, I cant see this as being the problem

 

[jibcl500]

I had a W202 with electrical problems like the wipers not turning off or the indicators doing what they wanted, windows opening but not closing etc, turned out to be a failing alternator, replaced it all was well there after.

I only fix Mercedes, I dont manufacture the faults, the question posted by Geoff is a request for a solution, Geoff has the same MB that I had this problem with. Many people here will offer solutions based on the problems they have had with their cars.

This model doesnt have the OVP relay if the alternator is failing and spiking the electrical system then problems like this can happen. Turn the ignition off and restart the car and these problems go away until the next time.

Dont doubt the advice given here, there are serveal people on this forum that do a ****** good job offering advice and support to others, and its FREE..



jib

 

[bigasotonuk]

I was just questioning how you come to the solution of the 'diode pack' i was,nt questioning your ability as a Technician. I am an Electrical Engineer and was trying to understand why this would be the case and as my sig. tells you i have 2 W202's and any knowledge that would increase my understanding of my own vehicle is welcome.
As it happens i have had occasional intermittent window problem but it has been on the auto down facility and sometimes the central locking won,t work from the button on the dash.(230k) these faults have appeared 2 or 3 times in a hundred thousand miles.
But i,m sorry if you took the above post personally as it certainly was,nt meant to be the case, but if you read the post after mine from a VERY well known member of this forum hes has written the same as me that he cannot see the connection between the windows/indicators and the 'diode pack'.
I appreciate that you are talking from experience of your vehicle but has,nt Geoff the right to hear from other forum members for their point of view on this fault.

 

[wireman]

What people are refering to as the diode pack is not any such thing.

The small package mounted on the alternators rear is a regulator/brush pack, the brushes supply a rotating field coil with an electric current from the regulator which measures the system voltage and gives more field current at reduced voltage and less at high voltage. The field coil is mounted inside the stator coils and is driven round by the input shaft this induces a hefty alternating current into the stator coils which requres rectification by the diode assemblies to produce the DC voltage required by the cars electrics.

The brushes given use wear down and begin to bounce about making the regulators job difficult with the result that the alternators terminal voltage (supplied to the battery and all the cars electrics) also bounces about all over the shop, this behaviour can confuse some electronic systems on the car, especialy the over voltage protection system.

The most common sign of brush trouble is intermittant illumination of the generator (ignition) warning lamp whilst the engine is running.

The alternator diodes are large bodied devices mounted in three sets of three on heat sink plates inside the alternator. you can change these but the alternator must be dismantled to do so and you need good electromechanical skills to do it properly.

If your so called auto electrician insists in calling the bit on the back a diode pack find somebody else to do the job since the one you've got is talking utter rubbish.

The reg pack costs about a tenner for the genuine bosch bit if you get one from a trade supplier, it is held in place by two small (M4) bolts and on many cars you can get it out without removing the alternator.

There is good money to be made from giving away lots of BS to unsuspecting punters, when there are lots of wires there is a lot of places to apply BS.

 

[Geoff W]

Hi everyone, I'm sorry my question has caused a bit of a ruck! it wasn't meant to!
When i post a question relating to a problem i have, i welcome suggestions and comments from anyone, whether or not it is good advice, I feel it is then up to me to judge what is probably good or bad advice, and act accordingly.
More so i feel that there is someone who has either had the same or relevant problem, or someone who is more technically minded than myself to diagnose the problem.
At the end of the day i won't be rushing out to replace anything just yet, the car has since behaved perfectly, so i feel it is wise to keep an eye on things and see if it progresses, in which case the cause may become more apparent in time.
But i do thank everyone for their suggestions, keep them coming, this to me is the whole idea of a forum.
Regards Geoff.

 

[television]

The point here is that the 2 said functions that have stopped will work in key 2 without the engine running, so the alternator should be dismissed as a likely suspect..

One thing that upsets things is water in the front fuse box, there are modified lids for this now

 

[BlackC55]

I would like to suggest another known fault.

Water gets into one of the window motors and causes this kind of problem especially if the car is parked on a slope.

 

[television]

I would like to suggest another known fault.

Water gets into one of the window motors and causes this kind of problem especially if the car is parked on a slope.

Thank you Black, sometimes post can be hard to follow, if the 2 faults did not appear at the same time, ones immediate reaction is to think that they are connected

 

[malcolm E53 AMG]

The problem might be as simple as an undervoltage battery if the unit is getting on a bit. It might have enough juice to start the car but not enough after initial start-up to run all the ancilliaries until full charge has been regained. Mercs are notorious for this from my experience. Worth checking out before going down the road of replacing parts.

 

[Geoff W]

Hi everyone. thanks for the suggestions, just to enlighten the indicators and the electric windows packed up together. first thing i did was checked for moisture in the front fuse box, but this was dry, and funnily enough it had not rained for quite a few days.
The only thing i did was to run my fingers over the top of the fuses, just to make sure they were seated properly, after that everything has been 100%.
I really don't think it is water related as the car is garaged and it has been very dry lately.
It could just have been a fuse not contacting properly?
Anyway thanks for all the help and i will keep an eye on it and keep you posted.
Regards Geoff.

 

[television]

Geoff why not clean the fuses with a non drying cleaner, it will stop all of the arcing and many problems

 

[Geoff W]

Hi Malcolm, thanks for the advice, do you have a name for the non drying cleaner, is it generally available? This sounds like a good idea.
Regards geoff.

 

[television]

Hi Malcolm, thanks for the advice, do you have a name for the non drying cleaner, is it generally available? This sounds like a good idea.
Regards geoff.

Any Maplin shop has it Geoff, I believe it is a servisol product, it will be with the cleaners in the shops