Newbie -few (hopefully !) small probs with A class

[wilsonio]

Hi there ,am new to the forum and have recently bought a little A class ,is a cool little car for the money I think ,have had a couple before including a 2.1 evo (that thing was like a dodgem car on steroids ! proper good fun car !).
Firstly and most importantly I have to guess how much fuel is in it ! have had the instrument cluster out earlier and checked the connection ports are good and free from crap but no avail ,have also disconnected the battery and reconnected but no good (windows puzzled me until I googled wtf was happening !) any help /suggestions appreciated and many apologies if this thread is in the wrong place ! -Scott

 

[AMGeed]

Welcome to the forum Scott.

The following website is a mine of good info for your A Class.

http://www.aclassinfo.co.uk/mypage.1.htm

 

[wilsonio]

Ok buddy no probs thank you ,shall have a nosey on that too

 

[AMGeed]

Copied from above website. It may help with your fuel gauge problem.


Hi, Lofty
Great site (just purchased CD).
I wonder if you or any of your site visitors can shed any light or offer any tips on this issue.
I have just bought an A140 year 2000 and it has a problem with the fuel gauge reading high.


My first thought was that the sender was the cause so I purchased a new one from Merc A168 542 09 17, removed the tank and pump but the sender was for a new pump design by VDO (I think) and mine is a Pierburg. The pierburg pump I see for sale on e bay, but not the sender on it’s own. Merc do not support the old pump any more so I would have to buy a new pump and sender complete.

New sender looked like this (mine was like the photo below and there was a different method of attachment to the pump)
This is fitted to my car, float rises in anti clockwise direction. Sender slides down onto pump when replacing.

I returned the sender to Merc but I did a dry test first by plugging it in and checking the reading on the fuel gauge. To my surprise the reading was identical to the Pierburg sender, i.e. when the sender float is in tank full position the gauge reads full and when in empty position the gauge reads HALF FULL? To me it seemed clear that the sender was not at fault so I refitted everything including a new fuel filter as suggested! Unfortunately I did not carry out a resistance test on either sender.

I then looked at the cluster which has at some point been changed as it has breakers white pen on. Whilst in Merc I photographed the Part numbers for the correct cluster for my VIN off the computer screen. The part number on the clocks in the car (A168 540 2947) did not match so I figured maybe the clocks fitted were calibrated for a different size tank?
I bought a new cluster A1685400447 from Euromerc (euromercwebstore) for £76 including delivery instead of £350 from Merc. I then had Merc Leicester fit and programme for £80.00 (1st quote was £150 Merc Birmingham)

The car has just run out of fuel at slightly above ½ full. After 11 pounds of fuel the reading is ¾ full and at about 25 pounds of fuel it’s full?
Any thoughts on this one?

In summary both the “incorrect fitment but new” and the “existing” senders give the same incorrect gauge readings
New cluster fitted with part number matching my VIN
If a new sender measures 0 ohms at full then I can’t see how I could have a poor connection problem in the wiring as the problem would be the reverse as I would not be able to obtain a full tank reading with a poor connection?
I have read on internet forums that on other mercs you can disconnect the pump connector and turn on the ignition to somehow reset the system but no one I have spoken to at merc has any suggestions about this on the A-Class.
Any advice would be greatly appreciated.
James.

Hi James thanks for your order for the CD I will put it in the post am tomorrow hopefully your get it Tuesday .
My reply
Wow you have has some work and cost trying to sort that out, My immediate reaction was that the wrong instrument cluster has been fitted, that does certainly cause a problem and as you have discovered all parts must match your Vin or you will have problems.

That also applies to the pump and sender unit, What I do not understand is why these have not matched up at some point while you have been chop changing.
As far as I'm aware all the A class w168 models have the same size tanks so I do not think the problem lies there but I know this problem has reared it is head before and do not recall seeing what the answer was . I do know the instrument clusters are not interchangeable

I am surprised that MB were not able to sort this out using 'star' Diagnostics if it is adjustable then it is on the equipment that the re adjusting would be done, did you raise that with them?
If you have now got the correct pump with sender unit and the correct inst/cluster then there is not other option as I see, other than getting them to do a diagnostics test to see if the circuit is showing a fault.

The cheapest way over that is to buy a had held diagnostics tool see my page from a company who will allow a discount, although the model shown I understand is not now available then do your own test and see if it comes up with a fault code.
The only other thing that comes to mind is if the previous owner tampered with the wiring to try and cure the fault of which he obviously would have been aware, a diagnostics test would hopefully show that in the form of a fault code.

Diagnostics tools are fine but located the meaning of the code is something again there are sites on the web that will give you the meaning of the code once you have the readings.
I sorry I can't be of more help on this one, you I think have done everything and more that I would have suggested the Inst /cluster being the first stop.

Owners feed back
Lofty,
Hi, CD received thanks.
Also I have good news in that the fuel gauge is now fixed.
I asked MB to check that they had not simply copied the error / incorrect settings onto the new cluster and indeed they had.
They have now corrected this for free – I think it’s a tank size option or something like that.
This means the cluster I removed would more than likely be ok if it was programmed correctly in the first place, but I bought the car with this problem so could not have known.

It is useful to know that anyone encountering this can sort it easily as long as MB listen to what you are saying they wanted to charge a lot more money to check the whole system before they checked their own programming. As I had already checked the sender it seemed pretty likely to be the problem.
Anyone who’s gauge says ½ full and the car runs out.
fill 10 litres from empty and the gauge says your 3/4 full., and 20 litres from empty and the gauge shows full, has a problem but as can be seen it can be corrected if Mercedes Use their diagnostics tools to re calibrate the readings shown in the fuel gauge which forms part of the instrument cluster.
James that's great news very pleased indeed to hear you have at last got a result. Good luck with the car.
Best wishes 'lofty

So if you have instrument cluster problems followed by a fuel gauge not reading correctly get mercedes to re-calibrate the instrument cluster, this can onnly be done by mercedes Bens or mercedes-Benz independent garages with 'STAR' Diagnostics equipment. do not be put off you like James do not need the complete system serviced or even checked, so do not get stung by MB service departments trying to charge more than is necessary.

 

[wilsonio]

Oh crap I thought this may have been a very simple thing ! lol ,well I shall have a good read through that but am thinking maybe not a quick easy fix for me ,am no mechanic at all but have had a lot of experience modifying and fixing bmws (e36's) ,a quick browse through that info is telling me that my prob could poss be the cluster has been replaced (there was a small amount of wear on the screws so somebodys been in it methinks ) ...to be continued shall report any fix I manage !

 

[AMGeed]

Before throwing any money at it, get a Mercedes indi' to put the car on STAR (MB diagnostics) and have any fault codes interpreted. If the cluster needs recalibrating, the indi' is the best person to do it. I wouldn't use a main dealer simply because of their inflated labour rates.

Let us know if you find the cause and fix.

 

[wilsonio]

Certainly will do my man ,many thanks ;-)

 

[wilsonio]

Ok so I havent fixed this yet but there is something I missed in the fuse box see pic thats hopefully attatched ! this leads got to go somewhere right ?

 

[AMGeed]

That is just an earth lead to the cover over your battery.
See a photo of my missus A160 battery.

 

[wilsonio]

Ahh crap oks well I'll connect the thing anyway -this is my car btw only a cheap old thing ,not bad for £500 though eh ?! Am going to get some new blue wheel centres (not sure if theyre advantgarde what Im thinking of ) and respray the wheels either gunmetal or black not sure which yet .

 

[AMGeed]

For £500 you can't go wrong really. Hope you get the other issue sorted soon.