twinz

Hey everyone,

Just purchased a 2003 Sl55 with keyless go. The car was starting and running up to par. For some reason this morning the car was completely dead. There is no power to anything, no lights, doors dont unlock or lock(good battery in keyless go card), etc..So I dont have the little mechanical key to open up the trunk because all I recieved was the keyless go card, so I cant get to the rear battery. I put jumper cables onto the battery under the hood and what do you know, the car still didnt have any power even with the cables attached. Is there some sort of security mode that shuts down the batteries with the keyless go? Did I do something wrong with the card? Please any info would really be appreciated!!!

Ausmbtech

You need a normal key. You really should have 2 normal keys for the vehicle and however many keyless go cards you want. Even in the owners manual it makes reference to the fact that if you are using the keyless go card that you should have a std key with you in case there is too much interferance for the keyless go to work. That's why the new keyless go system uses the std key as the keyless go key aswell.

Basicly the rear battery will be dead. The front battery operates the starter motor and EIS (electronic ignition switch) only. So to start the vehilce you either need a std key and insert it in the EIS or you need to get into the boot to jump the rear battery to allow keyless go operation.

m4xm1l10n

Well addressed answer

horrible

I thought I read on this forum that there was a switch of some kind
That if the start battery goes dead that it will allow the rear battery
To start the car. Is this not true?

moretech

I'd try pulling the starter battery and having it charged or at least checked for an adequate charge level and try again to start car. If it now runs you can order a regular key made at the dealer, you really must have that. My rear battery cut out one day for no real reason and I started the car using the starter batt. I had left the car unlocked in the garage so I did not use the manual key. Once running I then opened the trunk tightened my cables at the rear battery and no trouble since. it's been months now since that happened. If you lock up the car at night you really need that manual key or you are plain locked out without it. I often get message "chip card not recognized" and have to play with things a bit. As far as I can tell there is not any switch as you describe to use the rear battery to start the engine. forum members seem to agree the best front battery is from Mercedes, which also is mine, and jump starts may blow a small fuse in the front passenger floor well difficult to replace. I seem to remember members comments if that fuse blows the alternator will only charge the rear battery till replaced.

sl55_maniac

Never jump-start the starter battery!

horrible

Why? I have!
Only way I could start the car.

sl55_maniac

Best to trickle charge it and then attempt to start again. Jump starting can cause shortage to other modules/fuses which can end up being extremely costly.

horrible

Ok,Thanks but what if your stranded away from home and call triple A
Or MB.
How will they handle it?

stykshooter

I know on my SL when the starter battery died it gave no warning it just quit...

Girlfriends SL died @ at the store & wrecker service from MB replaced a battery on the spot, 200.00.


Had another friend who's serpentine belt broke between Dallas & Houston Triple A came out & towed to Houston, under warranty

bobterry99

This is unlikely to happen. The Starter battery is electrically isolated from the rest of the vehicle electrical systems except in the case where the Starter battery is healthy and the Systems battery is weak -- a situation identified by the "Consumers Offline" message in the instrument cluster.

CPDay

Jump starting can blow the fuses located in your 'Pass-Through Plating' located under the passenger floor. If any damage was done, it will likely show up as the 'Red Battery Icon' display on your dash.

It is much safer to slow-charge the starter battery and best to first disconnect it.

I learned this the hard way. See my thread elsewhere on this forum: 'Dreaded Red Battery Icon - How I Fixed It'

https://mbworld.org/forums/sl-class-...w-i-fixed.html

horrible

I called the service center at the local MB dealer here in New Orleans
And spoke to a technician.
I told him what some people on this forum were saying about jump starting our cars.
He said he never heard of any problems from jump starting our cars.

Rudeney

Having once worked at a dealership where cars would sit for weeks at a time and not get started, I became an expert at jump-starting MBZ's. I've jump started many R230's and there's no trick to it other than connect the cables properly to the starter battery. Don't "stutter" the final connection, otherwise you generate sparks and that could cause problems ranging from blown fuses to damaged SAMs.

At the dealership, we used a portable jump pack and it was often not strong enough to overcome a dead battery. Sometimes dead batteries act like giant resistors so the output of the jump back (or donor car battery) is reduced so low it won't run the starter. In that case, you need to disconnect the negative lead from the battery, then reconnect after starting the engine. Again, carefully and deliberately so as not to create sparks and surges.

If you really want to know how to jump start an SL, check the owner's manual - it's in the "Practical Hints" section.

CPDay

Perhaps this technician needs to listen a little more. There are plenty of first-hand stories right here on these forums.

RocketBoots

The owners manual seems to describe all the usual things to be careful of when jump starting any car. Just do it on the front battery only; very straightforward.