Help! 03 C220 CDI completely dead

[Big Slippy]

Hi,

Parked car earlier today, no problems. Wife went to start, remote wouldn't unlock (driver's door lock sticks tho) she opened door, alarm went off, pressed key fob again and nothing. Put key in ignition, but wouldn't turn.

Alarm stopped, car now completely dead, no lights, can't lock/unlock, auto wont move from Park, no interior lights, no hazards, no radio, key wont turn at all. Absolutely dead.

Tried disconnecting the battery and reconnected, made no difference.

Anyone had this? Anyone any ideas?

Thanks

[RBrown]

Is the battery completely flat?

I had a similar problem where the battery drained overnight (faulty tailgate problem) and car was dead. If it is this, I would recommend the car gets a health check by MB as it mucks up some of your electrics eg my electric windows wouldn't work after battery got going.

Good luck!

[magnum555]

Sounds like a flat battery, try recharging or replace the battery.

[rassi]

Be very careful when jumpstarting or replacing battery on the W203 - there are several relays that are very sensitive to any spikes in voltage, so there is a specific procedure to be followed. See e.g. here: http://forums.mercedesclub.org.uk/showpost.php?p=2...

[PrinceofWheels]

I had similar on my 04 270CDI. Locked it up mid morning, went back an hour or so later and nothing.
Mine was a heater element in the engine block that helps the engine block get up to temperature. When it fails it causes a short circuit which drains the battery at an alarming rate. After disconnecting and charging the battery it was reconnected and the discharge rate was measured. I cannot remember the exact values now but there was not much on the car with the ability to drain at that rate and the engine block heater element was swiftly identified as the culprit.
Hope it is something more simple for you as it was not a cheap fix.

[GregE240]

Try another key.

[GregE240]

Sorry - more info - had the same problem with my 210 - although it was more gradual - basically I think there was a dry joint in the key itself. Got back from holiday, got to long stay car park, exactly the same symptoms. Phoned my friendly neighbourhood MB specialist who said shake the key, then put it in the ignition, and if the steering column unlocks, start the car and just drive it home without turning the engine off.

Sure enough, tried the spare key at home, no problem at all.

Would also echo sentiments re jump starting - I wouldn't. Better to isolate battery and charge. Too many relays etc to potentially pop.

Good luck, keep us posted.

[Big Slippy]

I've tried both keys, same thing.
Took the battery out, charged it and checked it....battery tester showing good battery. Charged overnight, re fitted and car started straight away. Everything good.
2hrs later, completely dead again.

Is it just a process of elimination to check what could be draining the battery so fast. there must only be a few items that have that kind of draw.?

[GregE240]

Big Slippy said:

I've tried both keys, same thing.
Took the battery out, charged it and checked it....battery tester showing good battery. Charged overnight, re fitted and car started straight away. Everything good.
2hrs later, completely dead again.

Is it just a process of elimination to check what could be draining the battery so fast. there must only be a few items that have that kind of draw.?

Well, yes, but if you've got a 70aH battery, that's something pulling 35amps???

I think your battery might be shot. Can you put a multimeter across it and find out what the draw is?

[rassi]

GregE240 said:

Well, yes, but if you've got a 70aH battery, that's something pulling 35amps???

I think your battery might be shot. Can you put a multimeter across it and find out what the draw is?

I'd agree, that battery is almost certainly dead. Once it has been fully discharged and is of a certain age (has done thousand of cycles), it will not hold a charge.

[mbtech01]

Make sure you've got a good battery on car, either charge it up to strength or replace it & then try both keys again. Hopefully your problem will be solved. If you still can't unlock the car using the remote keys & the ignition won't turn then I'm afraid your ignition switch is likely to have failed. I've just had this problem on a friends C270cdi & had to replace the switch at a cost of £450 for the part. It's a bit of a procedure to replace as it has to be coded etc & is also classed as a theft relevant part so you'd need proof of ownership of the vehicle & photo I.d of the registered keeper. It also was on back order & took nearly 4 weeks to get from Germany. Fingers crossed you've only got a flat battery though.

[Big Slippy]

Update.

Battery charged up and drain was from an emissions thing that can't really see, but disconnected now and all OK. (Until we work out what it does (did!)
It's at the manifold near the starter but not really accessible.

Thanks for comments.

[mbtech01]

Glad you got to the route cause of the problem. The item your unsure about is the heater booster & this is a common problem on various cdi models in the Mercedes range causing battery drain.
Its basic function is to compensate for the reduced heat output of a cdi engine by warming up the engine coolant. It has a direct battery feed & if the internal circuits fail in the heater booster it basically allows for a huge current drain to occur. I've replaced several over the years but they're not cheap to buy & labour wise the starter motor has to be removed & cooling system drained & refilled.

[Big Slippy]

Thanks for that, most helpful.
Is it ok to run with it disconnected?

[mbtech01]

Should be ok. I know of a couple of cars that have the heater booster totally disconnected & they're still running ok with no problems. you'll obviously get a fault code flash up in the cdi control module if you scan it but it wont put the engine light on.

[DennisTheMenace]

My block heater failed 2 days before christmas, the current pull is around 25amps. no change in warm up time even with it disconnected.

[jeremyc]

PrinceofWheels said:

I had similar on my 04 270CDI. Locked it up mid morning, went back an hour or so later and nothing.
Mine was a heater element in the engine block that helps the engine block get up to temperature. When it fails it causes a short circuit which drains the battery at an alarming rate. After disconnecting and charging the battery it was reconnected and the discharge rate was measured. I cannot remember the exact values now but there was not much on the car with the ability to drain at that rate and the engine block heater element was swiftly identified as the culprit.
Hope it is something more simple for you as it was not a cheap fix.

Looks like PrinceofWheels wins the prize for the first to suggest this was the problem.

Seems like a remarkably common failure.

[GregE240]

If I'd known there was a prize I'd have tried harder