SL320 Electrical Problems

[adaptive]

I'm having an absolute nightmare with my 1995 SL320
The car had a problem with hunting at idle so it was booked in for a diagnostic with the main dealer who diagnosed it as a faulty Air Mass Sensor. They swapped it out but it made no difference.
After further investigation, they discovered that a fuse keeps blowing that handles some of the engine managment gubbins, including the o2 sensor. They couldnt trace waht was causing the fuse to blow, but they could change it while the engine as running and it would be fine, but as soon as the engine was switched off then restarted, it would blow
This has now been in the garage for almost a week with a bill so far of over £800 - anyone had anything like this before so I can give the mechanic something new to consider?

 

[kth286]

adaptive

One: it needs to be in a Merc specialist garage.

Two: you need to ask them what codes have been read off the diagnostic plug and you need to list them here for us to comment.

Three: ask them specifically what fuse keeps blowing

If they think someone else is on the case "they might get their finger out"

What miles has the car done ????

It's the same engine as in many W124 coupes, so lots of knowledge here.

Regards

 

[jberks]

I strongly second the 'specialist' advice.

It's outrageous that you are being charged £100 per hour so the mechanic can learn on your car. Just because it's a main dealer does not mean that they are experts on YOUR car. Think about it. The mechanic has probably been there for 2-3 years, 5 if he's an old timer. Most of the work he does is plugging in computers and changing the oil on cars like mine, at £100 per hour!. When he started, your car was already 6 years old, well out of warranty and many had already gone into the indie circuit so he simply hasn't seen many.

I've said before - cars over 6 years old are far better maintained at the specialist than the dealer. Chances are that yours is the first that mechanic has ever seen. He's very unlikely to have seen a 124 either. Even 210's are starting to be a rarity. A specialist however will probably have cut his teeth on these and will still work on them daily. As a result he probably knows whats wrong with it before opening the bonnet. Also, when I had an odd problem on my 4 year old E class, the dealer couldn't even recognise it had a problem. The indie agreed it had a problem, had it for 3 days, probably spent the best part of a full day on it (and fixed it!) but only charged me for 3 hours as he felt he should have found it sooner so the 3 hours was fair. He owns the place so can make such judgements. A service manager has to account (and charge) for every minute.

I'd agree a minimal charge with the dealer and take it away from them. Perhaps £200. In all fairness they can't charge £800 for failing to even diagnose, let alone fix a problem. Then give it to a genuine expert, who, by way of an extra bonus, will charge half what you're currently paying.
The longer you leave it, the bigger the blank cheque and the harder its going to be to negotiate it down again.

 

[adaptive]

Only me again!

i've just picked the car up after having the car sent from pillar to post
It's been to Mertrux in Derby (merc specialist - supposedly) and an auto electrician in Nottingham.

Unfortunatley, the problem is still there - hunting at idle and the constantly blowing fuse

the fuse that keeps blowing is fuse B according to the fuse panel and it blows everytime the engine is started

The car has done 114k

any sugegstions would be greatly appreciated, along with any recommendations for specialists in the midlands

cheers
Jim

 

[kth286]

adaptive

That's very vague.

Were you not told what the fuse controls.

With a car's ongoing develpment, fuses and relays get added to, depending on what extras are on the individual car concerned, so it would be useful if you could be more forthcoming, as this should not be a guessing game on our part.

Help us, to help you help yourself.

What fault codes were showing when plugged into the diagnostic connector - did you ask ????????

Look forward to hearing from you again.

Regards

 

[adaptive]

David, I'll try and speak to the mechanic at mertrux tomorrow and get him to give me the fault codes.
The initial problem was diagnosed as the O2 sensor and I know this has been swapped as the old one is in the car in the new parts box.
The original diagnosis was hampered by the continually blowing fuse and all I have gathered so far (from the garage I bought the car from) is the the fuse controls some of the engine management - very vague, i know
So far, parts swapped out have been the O2 sensor and the air mass sensor - again, dunno if these are the same thing as one was swapped at the main dealer who finally didnt charge for any of the work.
The O2 sensor was swapped at mertrux who thought they had fixed all the problems (hunting and blowing fuse) but after a couple of miles, the fuse started blowing again and again, the engine was hunting, so I think the 2 are linked. It was mertrux who charge £800 for their work.
After picking the car up today from the gar(b)age who sold me the car, they stated they had sent the car to Nick Ince Auto Electrician who had located the fault and fixed it. Got the car home, checked the fuse (which had blown) - swapped it for another, started the car and it instantly blew again.
I called the auto electrician who stated that he had the car in but didnt do any work as the garage had told him the fuse blew after a couple of miles of being swapped (this is incorrect as it blows everytime the car is started) and that he was under the impression that it was an intermittent fault.
The fault has been there since the day after I bought the car and the garage initially refused to do anything and would be passing on the mertrux costs to me on collection of the car. After getting trading standards involved, they have waived the cost but stated today that if the car still had a problem, they wouldnt incur any moe expense, pretty much washing their hands of it. (I'll sort this out with Trading standards as thats b******t)
At the end of the day, I love the car and want it fixed but it seems like its a needle in a haystack

 

[jberks]

If Mertrux have waived the £800 I suspect they are p..sed off and have thrown their teddy out of the pram. Not very professional but their perogative. They are not a dealer as such, but they aren't really an indie either as they are MB approved and probably charge accordingly. I suspect they used to be a dealer but lost their franchise in the recent changes, so chances are they are in some ways the worst of both worlds, in so far as they are too big for the owner to know who you are or to care. What care and effort you recieve has been decided by an accountant in exactly the same way as the main dealer would. You need an owner operator establishment.

All I can suggest is that you find another indie (perhaps a smaller properly independent one) and hand them the car. When I had a problem with my E240, in the end I handed it to my local specialist (gave the owner the keys) and said 'give me a call when it's fixed, not before, however long it takes.' . Took a few days, but it came back purring.

 

[hawk20]

The more I read on these forums the more I think the best advice is to go to Mercedes main dealers with factory trained mechanics. My dealer (Southampton) would be straight on to Mercedes Technical Department for advice on how to fix it. I don't know if you can get through to them via Mercedes Customer Service (the link is : -CustomerService@cac.daimlerchrysler.com ). But your main Merc dealer certainly can and they must have met the problem before. Good luck.

 

[Blobcat]

The more I read on these forums the more I think the best advice is to go to Mercedes main dealers with factory trained mechanics. My dealer (Southampton) would be straight on to Mercedes Technical Department for advice on how to fix it. I don't know if you can get through to them via Mercedes Customer Service (the link is : -CustomerService@cac.daimlerchrysler.com ). But your main Merc dealer certainly can and they must have met the problem before. Good luck.

This problem was first seen by a main dealer and diagnosed as a faulty air mass sensor which it clearly isn't. IMHO main dealers are good at providing the servicing on new cars and reading fault codes. If your car is >5yrs old then very few main dealer technicians will have any experience of them. Independant Mercedes specialists on the other hand will have trained with MB then setup on their own and know these car much better.
As your own car is only a year old and of the 'S' class variety then I expect the £100 per hour is not so much of an issue .

 

[hawk20]

I take your point on older cars. A good indie may have more experience with them. BUT it still staggers me why on so many threads nobody has contacted Mercedes Technical who have experience of all these cars, new, old and medium. I just feel from experience of my dealer, that a main dealer would have that as an early port of call if stumped. But no reason why indies can't use that source of information that I know of. And I assume owners can make contact too if they wish????

 

[Blobcat]

Another issue with dealers is that they do not mind charging you whilst they learn on your car. I know it sounds crazy but they will quite comfortably change black boxes until they find something. Even if they don't find the problem they will still expect you to pay for their time!
At a decent Indepentant Mercedes specialist they will generally find the problem faster as they will have more experience and charge you a lot less. Even if they don't find it as fast they don't always charge the diagnostic time as they are rising to the challenge and know that the owner will not be prepared to pay the full rate.
On a side issue I did note that there were a lot of Independant Mercedes garages in Germany which had previously been franchised. (You could still see the old signage). Looks like they have have a shake up same as over here.