1998 E300 How do you "reset" the electrical system?
 

So, I've had my car off the road for a couple weeks and I accidentally let the battery discharge to the point where even the little LED that flashes on the dash quit blinking. I did the following in this order:

1. I hooked a 1.5A trickle charger to the jump terminals over night. During the time the charger was hooked up, several of the dash indicator lights were glowing very slightly.

2. In the morning, the charger indicated fully charged so I removed the connections and tried to unlock the door with the remote. Not working. I opened the door, no interior light.

3. Next, I unhooked the battery and attached the charger directly to it and ran it for 6 hours, after which time it indicated fully charged. Still no remote unlock, no interior lights. I tried the key in the ignition and the column unlocked but when I turned the key, the alarm went off and would not stop until I removed the battery terminal.

4. I reconnected the battery terminal and now the column doesn't unlock when I insert the key and nothing else works. The only thing I notice that works is the little LED on the dash will flash when I lock the door with the key and it quits when I unlock the door. Nothing else on the car works or shows any sign of electrical life.

My question is: Is there a reset procedure for this? If the alarm is set off, is there a waiting period before the things will work again?

I have not tested the voltage yet at the battery but I'll do that tomorrow.

Thanks.

Sorry
 

The Mercedes security system has fully engaged.

It is in disabler mode.

The vehicle needs the MB dealer to unlock the system.
Some dealers have mobile technicians available to fix this at your location. :)

Or you can buy the Mercedes STAR diagnostic tool:
A China illegal version (that 50/50 odds may work) is $500.00 - $3,000.00 USD.
The legal authorized Mercedes STAR diagnostic tool is a yearly subscription of roughly $28,000.00 USD.

If I recall correctly, there is one more level to that security system = if it goes into stolen mode = not even the dealer will be able to make the car function, without replacing module$.........

.

One possibility that came to mind was that the battery charger was giving a false reading. Not that the battery charger is faulty, but rather that the battery is so discharged, it won't accept a charge. This is what I am finding with my tractor battery on my Cub Cadet when the battery is kaput. Nothing was wrong with my battery charger. Just an idea.

Usually just taking off the terminals for a bit, and clamping them back down does the trick to reset most faults. It sounds like though, it is in safe mode. You would need STAR for this to unlock it.

Hopefully the dealer provides this roadside service free of charge for making such a pos of a system.

Does the key in the trunk now work to get the alarm theft system disengaged like on teh old w124s?

Am i understanding correctly that if i take the battery out of my w210 e300D for a week and put it back it it is going to think my car has been stolen and disable it?

Wow....this is a bit disconcerting...to think that simply a drained battery could create this kind of a headache.

OK, thanks. The car is sitting on my carrier from a previous catastrophic failure so It's not a big deal to haul it down and have it reset.

Make sure the battery is a good one. I am not sure I've seen where you have verified it is a good one.

Does your car have a second battery like the CDI's for backup of critical data in case the main battery fails? If not, please add one.

If your battery was that discharged, I cannot see how a 1.5 amp trickle charger could bring it back to a fully charged state overnight. I would definitely double check the state of the battery under load conditions. You could have a bad cell that will not show up until placed under load. Good luck

What is the story on that failure??

I think would be pretty challenging to retrofit because critical circuits could have to be separated into a different circuit that could be passed over to the second battery electronically when the primary got too low. I would be interested in thoughts on how it could be done though.

This is correct, it seems like the small charger doesn't really have the power to bring back the battery from such a low charge state. I'm going to try hooking my big charger to it this evening and check the results tomorrow morning.

Imagine the automotive equivalent of an aortic aneurism but that's a story for another thread. I have pictures too! :)

Maybe easier said than done.

Identify the critical circuit and isolate if necessary.

Determine it's power requirement and choose a suitable backup battery.

Use 2 isolation diodes which powers the critical circuit in parallel with the main battery.

When the main battery dies, the backup battery continues to power the critical circuit.

I don't really understand what has gone on here. Surely disconnecting the battery wouldn't cause all of this trouble with the anti-theft device?

If it was so important (to allways have power) I'd imagine that there must be a back up battery like there is on a computer - these used to be called CMOS batteries - they'd keep basic things like the clock running whilst the computer was switched off.

Shame there isn't an online manual for the W210 I'd be interested in reading up on it. A generation earlier W201 / W124 - disconnecting the battery is a great way of clearing fault codes!

Diode isolation would separate the two batteries, we call that a "best battery selector" at work. Problem is that you also have to figure out how to keep the aux battery charged. They make a device for travel trailers that does this function.

That whole adventure scares me, about 2 weeks ago my W210 battery was getting weak. No problem, I thought. I pulled out the battery at probably 8 am, threw it in the back of the ML, ran a bunch of errands, and finally got back to installing it in the car about 5 pm. Luckily for me the car started normally and all I had to do was re-sync the windows and sunroof and put the CODE back in the radio.

If I had to do it now that I know about your situation, I would have set the battery from my 124 in the battery well and hooked it up, just to keep the electronics happy in the W210. Scary stuff that the car can lock itself up just from lack of power. Or ran jumper cables between the 2 cars.

That should not be a problem. Use 2 diodes in series. Main battery go through both diodes to the isolated critical circuit. Backup battery go through one diode and gets charged. Critical circuit sees 2 diode drops (1.2 V) of main battery and one diode drop (0.6V) of backup battery, which shouldn't be a problem.

FYI
 

The 1.5A trickle charger is for maintenance only.

On this, and most newer vehicles the computer strategy is set with power thresholds = the owners manual requires disconnecting a dead battery for charging.

If the dead battery is connected during charging, a 15, 25, 50, 100 AMP charger will voltage SPIKE the electrical system at least once.

Using the 1.5A trickle charger is worse, because it crosses the module power threshold = engaging/dropping, engaging/dropping, etc, the self check systems that when new/perfect draw 1.2A - 1.4A.

The security system is also seeing this on/off cycle a huge number of times, before/if the trickle charger rises above the module power threshold = the strategy assumes someone is trying to steal this vehicle.

Once the security system is engaged = a current subscription Mercedes STAR diagnostic tool is required to unlock it.

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Something does not sound right with this one. I have had a 99 E300 in the shop for a couple days without a battery in it and did not have any issues whatsoever. My suggestion is to put a known good battery that is appropriately sized in it and see what happens.

My 99 never had the computer module die, but it has happened to friends' of mine that also had the same '99.

I'm thinking a fresh battery might tell a lot about the system.

I was thinking the same but it seems as though whunter has the answer here =>


<= message is don't attach a trickle charger to the battery when it is fitted to the car (???)

This is somewhat what I have experienced so nowadays if I want to charge a battery while it is in the car I just disconnect the negative cable.

It's alive! Last night, I disconnected the battery and gave it a proper charge for a couple hours with my charge/booster and now everything is working again.

Looking back on the sequence of events, on that first morning, after charging all night with the trickle charger, I believe the battery voltage was still down around 10v. Switching on the key must have pulled the voltage down below one of those "thresholds" that Roy spoke of earlier and that knocked the car out completely. It's not like older cars that will give some indication of battery weakness, it just flat out doesn't respond - as if the battery isn't there.

The take home, mistakes I made:

1. Not checking battery voltage before and after charging.
2. Placing a trickle charger on a highly discharged battery. (Don't send a boy to do a mans job.)

There's a somewhat dodgy video on youtube concerned with changing a battery on a W210 - the chap makes silly mistakes like disconnecting the positive side first etc but does show how you can check the battery supply voltage on a control panel for the a/c

I don't know if your car has this feature of course...

KarTek, what kind of voltage readings do you get from the panel? Both of mine show 13.3, maybe 13.5, after car running for a few minutes, no accessories on. I'm told that this reading is skewed low by design.

The w210 has a battery disconnect going to the pos terminal. It's located under the rear seat by the carpeting.

The car won't be running again for a few months while I do some major modifications. I know that when I tested the battery about 12 hours after a proper charge, it was showing 13.2 v.

That's interesting, I just took the terminal off the battery. I'll have to look for the disconnect.

I made a mistake and wrote things out of order. It should read:

"On that first morning, after charging all night with the trickle charger, I tested the battery voltage and it was down around 10v. Switching on the key must have pulled the voltage down below one of those "thresholds" that Roy spoke of earlier and that knocked the car out completely. It's not like older cars that will give some indication of battery weakness, it just flat out doesn't respond - as if the battery isn't there."

I fixed the original post for more detail and clarity.

Not the positive terminal but the negative terminal has a disconnect behind a cover plate on the dividing wall between the under seat area and the right rear passengers foot space.

Takes a 13mm or 1/2 inch socket.