C240 2001 Alternator

[dave@mdsys.co.uk]

Chaps. My alternator is not giving what it should and I need to replace. But reading postings tonight it looks as though I need to buy a 'reg pack' and not replace the whole unit.

Any advise on where I can get these and how to fit would be appreciated.

Thanks in advance,.,

 

[tamrsoft]

Try just replacing the brushes first, the regulators tend to either work or not work. Another possibility maybe blown diodes and if like my alternator they maybe impossible to replace.

 

[television]

How do you know that it is not giving what it should

 

[type49]

Try just replacing the brushes first, the regulators tend to either work or not work. Another possibility maybe blown diodes and if like my alternator they maybe impossible to replace.

The regulator pack includes brushes & diodes

 

[dave@mdsys.co.uk]

Thanks for the info so far.
My problem is as follows:
Flat battery when the car is left for more than 2 days.
Battery checked and all O.K
Alternator checked by RAC and they say that it is putting out only 12 amps at peak.

My concern is therefore that:
a) the alternator isn't charging sufficiently to recover the battery after starting.
b) that the RAC man found that there was approx 1 amp being drawn even when the keys are removed and left for 30 minutes.

a) is one problem but b) indicates something is not switching off as it should.

Using basic 'looking and listening' I have found that in the overhead console there is a grid type of space which seams to have a fan noise comming from it. I thing this is something to do with the air con but could be wrong. I can't find anything running other than the alarm, which I have taken to switching off the internal sensors and read lift sensor.

Any more ideas please.... 'television' you seem to know about such things....

 

[type49]

Behind the grill is an aspheric motor. You are correct, it is to draw in air to measure cabin temperature.

 

[dave@mdsys.co.uk]

Should this not turn off

Thanks for that learn't something new again, But shouldn't this motor turn off.? Could this be causing the amp draw?

 

[television]

for a start, a 1 amp drain will flatten the battery in 2 days, I believe that the little fan runs for about ½ hour after switch off, maybe type 49 knows if this is the case

I do not think that you have alternator problems as the engine draws 30 amps, anything thats left over goes to the alternator, but these things are not designed to charge flat batteries, so I fail to accept the Patrol mans diagnosis

What are the first 6 numbers of the vin

 

[dave@mdsys.co.uk]

Well that bit matches the two day bit.

I take it that the number is the one on the black sticker inside the drivers door. if so then 1718252 8.

When running at 3000 rev's with everything off there was an amp measurment of 12 amps. When all lights etc on the amp measurment of 32amps.
This was done with a clamp on amp meter. I have also had the battery checked with tricky kit at a local garage and they said that there wasn't any problem with the battery or the alternator.

Can you see why I need help. I'm sure the local Merc dealer would help but would want to do a full electrical diag at a huge cost..

 

[television]

The VIN is on log book or at the bottom of the window front

 

[dave@mdsys.co.uk]

Dough!!! as homer would say.

WDB203261. I have the full number and happy to exchange privately if required.

 

[television]

Dough!!! as homer would say.

WDB203261. I have the full number and happy to exchange privately if required.

Thats fine, I never need the full number

 

[dave@mdsys.co.uk]

...............................

 

[dave@mdsys.co.uk]

I'm still looking for help on this subject. Can anyone help?

 

[television]

I will check for known issues this eve (early) if there are no known faults its a matter of getting an ammeter and checking the current flow

 

[dave@mdsys.co.uk]

Thankyou..............

 

[television]

I have been through the whole data base and there is nothing known. This means that you will have to get an ammeter and connect it up and withdraw the fuses one by one until you find the circuit that the fault is on

Re the little fan in the roof, this may run for a bit after stopping, perhaps you could leave a window down and check it after ½ an hour to see if it is still running to see if that is the fault, The Command may not be going to sleep

 

[dave@mdsys.co.uk]

Thanks for that... as you sound like you know your stuff could you advise on..

a) where all the fuses are
b) How best to check the circuit using an ammeter to check the circuit
c) anything I need to avoid doing, don't want to cock it up.

?? would the men at Merc be able to plug in and diagnose the system or would they need to do the same step by step?

 

[television]

MB cant do any more than you can, and there is no diagnosis for this, just working your way through the circuits.

In the link you will need to open 062-064-080-084

http://www.detali.ru/cat/oem_mb1.as...722.696&GM=716.623716.634&CT=F&Cat=69J&SID=54


The meter must be connected in series with the battery, the reading noted, should not be more than around 70m/a once the car has gone to sleep.

Common faults = boot light, mini fan, Command

See how it goes

 

[dave@mdsys.co.uk]

Update

Hello, thought I would drop an update in here for future reference, as I'm in here looking for info about Crank position sensors (as mine has just packed up, leaving me stranded in wales....) anyway the fault was tracked down to the drivers seat control unit.
This is located under the drivers seat....

£289 to replace, but I'm the only driver it's unplugged and all the power issues have gone away.

My local Merc dealers comment was "oh, we've had a number of those fail..." They were still offering to do a full diagnosis though, even when they had this information....

Anyway back to the CPS and thanks to Television who I see posted a doc link on this some time ago. It's now down to the nice merc road side man to source one and try to fit and get me away from Wales.....

Cheers and thanks to all on this forum..