Mysterious Mercedes Fault

[EnthuZiaZT]

Had a problem with our Merc over the weekend, the battery ran flat on Friday, which is not surprising as Sandy only does 3 miles to work and back each day, driven mostly in the dark at this time of year.

Jump started the car on Friday and left the engine running to charge the battery. Fine all day, not used at all Saturday.
Battery dead again on Sunday morning, so decided to put the battery charger on it. Disconnected the leads to the battery, unscrewed the plugs to vent the dangerous gases and charged the battery for seven hours. Reconnected the battery to the car, switched on the ignition and warning lights appeared on the dashboard including ESP? Car started fine and all appeared normal otherwise.

This morning, went to get into the car, but it would not unlock electronically, so used the emergency key to gain entry, got in, tried the key in the ignition and the car started perfectly. However no other function, lights, indicaters, guages etc worked. Warning light on the dashboard advising visit to workshop.

Took car to the Mercedes Specialist, who services it regularly, expecting it to be something simple like a relay. Diagnostic checks did not indicate a fault in any area. They fitted another battery on loan, but still no change.

Anybody any ideas?? It is booked in on Thursday, but the garage is puzzled by the fault. Has anyone had anything similar happen???

 

[badman gee]

Had a problem with our Merc over the weekend, the battery ran flat on Friday, which is not surprising as Sandy only does 3 miles to work and back each day, driven mostly in the dark at this time of year.

Jump started the car on Friday and left the engine running to charge the battery. Fine all day, not used at all Saturday.
Battery dead again on Sunday morning, so decided to put the battery charger on it. Disconnected the leads to the battery, unscrewed the plugs to vent the dangerous gases and charged the battery for seven hours. Reconnected the battery to the car, switched on the ignition and warning lights appeared on the dashboard including ESP? Car started fine and all appeared normal otherwise.

This morning, went to get into the car, but it would not unlock electronically, so used the emergency key to gain entry, got in, tried the key in the ignition and the car started perfectly. However no other function, lights, indicaters, guages etc worked. Warning light on the dashboard advising visit to workshop.

Took car to the Mercedes Specialist, who services it regularly, expecting it to be something simple like a relay. Diagnostic checks did not indicate a fault in any area. They fitted another battery on loan, but still no change.

Anybody any ideas?? It is booked in on Thursday, but the garage is puzzled by the fault. Has anyone had anything similar happen???

not had a good weekend have we

loose wiring anywhere? or a loose earth wire?

thats all i can think of.

:|

 

[GazHyde]

I would have though knackered battery as a first call, but clearly not that. Second thought would be dodgy earth connection as b.m.g. says.

Other than, I guess it's sit back and wait for the diagnostic fee from the garage :-ss

 

[EnthuZiaZT]

Had a problem with our Merc over the weekend, the battery ran flat on Friday, which is not surprising as Sandy only does 3 miles to work and back each day, driven mostly in the dark at this time of year.

Jump started the car on Friday and left the engine running to charge the battery. Fine all day, not used at all Saturday.
Battery dead again on Sunday morning, so decided to put the battery charger on it. Disconnected the leads to the battery, unscrewed the plugs to vent the dangerous gases and charged the battery for seven hours. Reconnected the battery to the car, switched on the ignition and warning lights appeared on the dashboard including ESP? Car started fine and all appeared normal otherwise.

This morning, went to get into the car, but it would not unlock electronically, so used the emergency key to gain entry, got in, tried the key in the ignition and the car started perfectly. However no other function, lights, indicaters, guages etc worked. Warning light on the dashboard advising visit to workshop.

Took car to the Mercedes Specialist, who services it regularly, expecting it to be something simple like a relay. Diagnostic checks did not indicate a fault in any area. They fitted another battery on loan, but still no change.

Anybody any ideas?? It is booked in on Thursday, but the garage is puzzled by the fault. Has anyone had anything similar happen???

not had a good weekend have we

loose wiring anywhere? or a loose earth wire?

thats all i can think of.

:|

One of the best, life can't get much better than this. ~x(

What a weekend, If not covered in cement or kerosine,(see East Anglian pub thread) it's now car electrics.

Zed safe in garage, but perhaps I better not say that. [-x :-ss

 

[EnthuZiaZT]

I would have though knackered battery as a first call, but clearly not that. Second thought would be dodgy earth connection as b.m.g. says.

Other than, I guess it's sit back and wait for the diagnostic fee from the garage :-ss

The garage have already done that today, Gary and are totally foxed :-\

 

[Titan]

Electronic systems seem to get more and more sensitive. It seems as though yours has got its wires well and truly crossed.
Is there a "factory reset" or similar?
Have you tried disconnecting the new battery for eg an hour to see if that may clear some parameters?
These are just guesses and come with no guarantee!


Sent from m'iPhone using Tapatalk

 

[EnthuZiaZT]

Electronic systems seem to get more and more sensitive. It seems as though yours has got its wires well and truly crossed.
Is there a "factory reset" or similar?
Have you tried disconnecting the new battery for eg an hour to see if that may clear some parameters?
These are just guesses and come with no guarantee!


Sent from m'iPhone using Tapatalk

Thanks Titan
I'll try both of those and see what happens. :ympray:

 

[DangerousDave]

Have you tried disconnecting the +ve lead (wait 30 secs) and earthing it? This ensures that the whole vehicle is at 0v before you reconnect the battery.

The 30 sec wait allows any capacitors to discharge before you earth the +ve lead.

Have you have tested the static voltage (12v ish) and the running voltage (14v ish). What does voltage drop to when starting (11v ish)? What is the static current draw (0.1A ish)?