Bad battery? Bad starter? Bad something else?

[Darragh1]

HI again,
Re: WDD2122032A...2010 E250 Estate OM651.

Bad battery? Bad starter?

I have an intermittent problem which is rearing its head.

Sometimes when I press the fob unlock button it doesn’t work even at close range. Fob battery is new and replaced twice, just in case.

Similarly, when I turn the key all the rest of the car including lights indicate it’s ready, but no start. I hear no click or clicking either.

If I turn the key back to the off position and then try again, the car starts.

Is it a bad battery? I don’t have the stop/start option and I think I have just the one main starter battery. I don’t know how old the Fiamm vr800 is as the date has not been stamped. It is probably a few years old. I own the car one year and it is my first diesel Merc. The alternator was rebuilt when I got the car if that is relevant.

Using the phone and ok buttons on the steering wheel and the key in position one, the car battery voltage reads 12.2v or 12.3 and it once read 11.9. However, with ignition on and when driving it goes to a fairly steady 14.6v.

For this car is 12.2 or 12.3 high enough or could this be the source of the intermittent fob not unlocking or locking and the non start?

If this is a starter issue, where might I start? Or something else obvious?

Much obliged for your ears loaned
Thankles,

D.

 

[AMGeed]

Possible starter relay or ignition switch fault if the engine doesn't turn over.
Really needs an indy with Star diagnosis to check what is going on.

 

[johnsco]

Does the OP have a second key to try ?
This will eliminate the possibility of a dodgy key.

 

[Darragh1]

I connected to my ctek5.0 for a few hours and the battery is charged fully. I then read 12.2V inside the car (pressing phone and ok on the steering wheel). Then I checked the actual battery with the multimeter and it read 12.62V. I'll check it later but I can presume for the moment the battery is okay and not the issue.
The starter relay (0025422319 mb/tyco) contacts are shiny and clean. I have another from another working mb car which I can try into it next time the fob delays or doesn't unlock/lock/start. The starter fuse 20amp.no.7 in the main fuse-box is good.
Also I will also try the second key.
I really like the car but I can safely say it has been the most expensive merc I have owned, in terms of throwing at it replacement parts, labour and vat.

I'm back at the indie soon for something else and I'll ask him to do a plug in for codes. I must buy a code reader.
Any more suggestions that I can be getting on with meantime, are welcome.
Thankliest regurgitations,
D.

 

[grober]

THEORETICALLY A 12 VOLT LEAD ACID BATTERY= 6 CELLS AT 2.2 VOLTS =13.2 VOLTS ----12.62 AFTER A CHARGE SEEMS A BIT LOW- SHOULD BE A DATE CODE ON THE BATTERY SOMEWHERE? 14.6 IS YOUR ALTERNATOR VOLTAGE

 

[Benzowner]

Battery at 12.2 to 12.3 would indicate a failing battery should be nearer 12.6 and the 11.9 reading would suggest a cell gone. The 14.6 is normal charging voltage.

 

[Darragh1]

With engine off , according to the steering wheel buttons menu it reads 12.2 but the 'real' reading with multimeter contacting the battery is 12.6.
With engine on , the car is a fairly steady 14.6.
No date stamped on battery.

 

[DSM10000]

With engine off , according to the steering wheel buttons menu it reads 12.2 but the 'real' reading with multimeter contacting the battery is 12.6.
With engine on , the car is a fairly steady 14.6.
No date stamped on battery.

The on board voltage reading is always lower than that taken at the battery due voltage drop through the wiring etc.

Your battery sounds OK.

 

[BigJase88]

The on board voltage reading is always lower than that taken at the battery due voltage drop through the wiring etc.

Your battery sounds OK.

You won't drop .4 of a volt in a car wiring loom. Its not possible

 

[Darragh1]

Does this intermittent issue (which didn't arise today) point towards a fob problem?
If there is an ignition switch or starter problem, I presume that would not effect lock/unlock?

 

[mioba]

I cant see the fob being issue as it starts second
time, but use second fob,
I was thinking alarm control module under wheel arch.

Needs
code
readp

 

[Darragh1]

This morning inside the car battery was 12.1 and multimeter to battery was 12.26. Key turns but the final ignition switch didn't work, the car didn't start. I tried the second fob too to no avail. There is no cranking to be heard. I attempted jump start but no change. The Headlights work and all the instruments etc. The starter relay clicks when I turn the key and I can hear what is probably fuel pump engaging.
I know it will need to be brought to my indie for codes. Is there any other basic check I could do myself ( without code reader) to isolate the problem?
Thankles,
D.

 

[Darragh1]

I checked the starter fuse and it was broken. I replaced it and the car started three times i.e. it didn't blow. Either pulling the fuse yesterday upset it a little (unlikely) or I have a starter? Issue which will blow the fuse again.....
Wisdom appreciated,
D.

 

[colinallcars]

This morning inside the car battery was 12.1 and multimeter to battery was 12.26. Key turns but the final ignition switch didn't work, the car didn't start. I tried the second fob too to no avail. There is no cranking to be heard. I attempted jump start but no change. The Headlights work and all the instruments etc. The starter relay clicks when I turn the key and I can hear what is probably fuel pump engaging.
I know it will need to be brought to my indie for codes. Is there any other basic check I could do myself ( without code reader) to isolate the problem?
Thankles,
D.

Try another battery?

 

[Darragh1]

I need the correct mb part number for the starter and I don't have access to the russian parts site i usually use. Is there a magic way of looking it up myself that you guys know about? Or could someone give me the p/n. My car s212 e250 2010 204bhp wdd2122032A295207. It has agm batrery but no stop/start option if that's relevant.
Thankliest regirgitations,
D.

 

[alecmascot]

A6519060026 for non start-stop, Denso

 

[Railwayman]

This morning inside the car battery was 12.1 and multimeter to battery was 12.26. Key turns but the final ignition switch didn't work, the car didn't start. I tried the second fob too to no avail. There is no cranking to be heard. I attempted jump start but no change. The Headlights work and all the instruments etc. The starter relay clicks when I turn the key and I can hear what is probably fuel pump engaging.
I know it will need to be brought to my indie for codes. Is there any other basic check I could do myself ( without code reader) to isolate the problem?
Thankles,
D.

Think you need to replace the battery based on those readings.

 

[E55BOF]

If the starter relay clicked when you turned the key (post 12), that suggests to me that the fuse was not blown then. If it was subsequently blown, that would suggest a fault in either the starter solenoid or the wiring to it.

 

[Darragh1]

Okay.I will check the click of the relay again. I know how involved it is to remove the starter motor -

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The solenoid sits on top of the motor, right? If so, i presume it is the same labour to replace the solenoid as replace the starter, or is there a shortcut? More cost effective to do the whole starter? (2010 car with 235000kms) Mb starter is €500&vat, oem denso is €170.
Thanks,
D.

 

[Darragh1]

Think you need to replace the battery based on

I do wonder if a new battery might fix the problem. There is a software update due and a recall on the positive battery 'pre-fuse' terminal so I wonder if that is connected. It will be a month before I get the car in for that. If related.