Air Pump and Alternator Faulting

[Farjer]

Hello everyone, hope your all keeping warm if in the UK.

Well after along time saving I finally got round to fitting a Recon 150amp Alternator and find all my instrument lights come on at start up and the faintly glowing battery light has gone... Hooray!

Sadly, the very cold weather has killed by dying air pump (which has been on the way out for the last 14mths).

Anyway, christmas is on hold now as yesterday got MB to fit a new pump but now find my 4 day old alternator if faulting; Back to the lack of instrument lights at start up and the battery light constantly glowing!!

I know MB didnt disconnect the battery when the air pump was fitted cos when I picked up I found all my pre-set radio station still there in the same order.

Any ideas, anyone, as to what might have caused this?

Is it necessary to disconnect battery for a new air pump and if yes, but its not done, would this knacker the alternator?

I always find MB fix a problem but cause a new one in the process.

Hope to hear with your thoughts on this matter.

[malcolm@mill.me.uk]

it is unlikely that the battery was disconnected.

you probably have a fault that is showing up, by pure chance, as the work is being done.

one possible cause is a bad battery earth... it would cause the problems you indicate..... but the radio has storage capacitors (and some can hold memory a long time) which would keep the memory with very small power interuptions... whereas other circuits would notice.

likelist problem is the -ve battery cable where it is bolted to the bodywork earthing stud (bottom end of cable)

undo connection and scrub the stud, nut, washers and cable terminal with a small wire brush untill shiney.... then reassemble.

if it doesn't cure it, it will have done no harm and you know it is a good connection

its very common at this time of year

[Farjer]

Cheers for the suggestion Malcom.

My battery is under the passenger seat along with the fuses so it should be OK but will check it out. Is there an earth lead sonewhere which might also be causing problems... On the alternator?

My non MB stereo does not hold stations when disconnected from power, got battery changes down to 10mins and always have ti reset stations on my radio.

Have a merry christmas.

[bigchrisrogers]

Originally Posted by Farjer

I know MB didnt disconnect the battery when the air pump was fitted cos when I picked up I found all my pre-set radio station still there in the same order.

Any ideas, anyone, as to what might have caused this?

Is it necessary to disconnect battery for a new air pump and if yes, but its not done, would this knacker the alternator?

I always find MB fix a problem but cause a new one in the process.

I'm not necessarily saying it is the right thing to do but . . .

I have often reomved my suspension air pump and on no occassion did I disconnect the battery. Never had a subsequent electrical problem in this respect.

Rgds
Chris

[Farjer]

Chris thanks for the message.

I make sure mechanical repairs are carried out by a friend who owns a garage.
Sadly he doesnt have any computers to plug into the vehicle so I must see mh local MB dealer.

Does anyone know where the oil pressure switch is and is there also a sender somewhere else

Just feed up with them as they fix one thing but it leave with a new problem which is conveniently missed but is always about £400 to fix (this has been on 3 occaisions).

It recently went in to check a flashing oil light... The computer said wiring fault, they just wiped it from system and gave vehicle back... Half an hour after pick, oil light flashing whilst driving and at stopping to check, the air suspension warning light flashing at engine switch off.

A new air pump was only fitted days earlier when the whole aif suspension system was checked.

[malcolm@mill.me.uk]

you don't say what model the vehicle is..... preferably with the vin number (down the opening edge of the front right hand door on 639 (new shape) or under flap between front right hand door and seat on 638 (old shape)

[malcolm@mill.me.uk]

assuming yours is a 638 v280 ambiente with the vin starting 6382..... here is the detail.......

the likely fault is a bad electrical contact on the sensor......... BE WARNED the connection is a 2 pin plug / socket... they corode like mad and are likely to have destroyed BOTH the pins on top of the sensor AND the connector on the cable.

you can get both bits from mb..... OR you can bodge the connection by attaching a "lego block" type of electrical connector strip in place of the cable connector.

[Farjer]

Malcolm, many thanks my vehicle is a 1999 V280 (638).

I was not able to open the txt document but the pdf is exactly what i need.

My experience with local MB dealer is if the job isn't a "unit replacement" (if that makes sense" they don't really know what to do or want to do it as all the mechanics are very young and (via the viewing window) rush around like mad.

What you say about the connectors is useful... I recall someone else saying its not uncommon for oil to work its way into the connectors causing problems. The initial symptoms being flashing oil lamp at start up. Goes off once engine running. Now at every pot hole it flashes whilst driving. Latest being no longer flashing at start up. Constant flashing once engine running or driving.

From the schematic and description you supplied the job appears to be really fiddly which may explain why the fault was wiped from the computer and the vehicle handed back without anything practicle being done... So i could breakdown half an hour after pick up from MB.

Many thanks again and will keep you informed of progress made to resolve this and the alternator fault.

[Farjer]

Forgot to add that as the v280 is off the road had been running around in my 1969 VW Beetle till this evening when some looon lost concentration and rear ended me whilst stopped at lights.

Bad luck seems to be lurking at every corner for me.

[malcolm@mill.me.uk]

I've changed the txt file to a pdf........ if you have never removed the grill or headlight before... its useful reading and difficult to work out without help.

take my advice and clean BOTH headlights connectors whilst you can get to them..... its the rectangular 6 pole connectors on the back...

the headlight and indicator come out as a single unit

I tend to sandblast the connectors as its quick, easy and thorough..... and I've got a grit gun.

most lighting faults are due to these connectors

KEEP THE COVER PLATE ON THE BACK OF THE HEADLIGHT WHEN CLEANING

upgrade BOTH headlight bulbs (main and dip are seperate bulbs) to Osram Nightbreakers... cleaner white light and the brightest currently made standard headlight bulbs