yeezer1

I've searched this forum, and there have been similar problems, but I couldn't find my exact issue, so I hope you can help me with this.

I only drive my 2004 SL500 about once a week, and when I do, it's usually just to somewhere like the local grocery store. Every time I drive, the consumer electronics are offline (I get the error message in my display), but they come back on after a few minutes. This has been happening for quite a while, pretty much ever since I stopped driving it every day. So this may be normal, but I'm wondering if it's an indicator of other problems?

For about the last month, my keyless go has no longer worked. I have to stick the fob into the ignition in order to drive. When I try to hit the Start button without the fob in the ignition, I get the "Key not recognized" error message. I've tried it with the fob in many different locations, inside and outside of my purse, in my hand, etc. But I can still lock the car by touching the handle button, or unlock it by touching the handle... usually. It's fairly consistent that I can unlock/lock it normally on the driver side door, but I haven't had much luck with the passenger door or trunk.

I only have one smart key which was newly replaced about 2.5 years ago. I used a battery tester to see that the battery is still good.

Before I go to a dealership, I'm wondering if you have any ideas of what should be checked? From what I gather, I possibly need to:

• Change the battery in my smart key (even though it tested good)
• Change my secondary/consumer electronics battery
• Check the main/starter battery because the consumer battery will auto-disable itself if the main battery is weak
• Check the alternator or other electrical system?

Any other ideas? I don't know anything about car mechanics, so let me know if I'm off.

Thanks!

sifis

It is the battery in the trunk. Buy a CTEK 3330 (battery maintainer) on ebay for $52, connect the battery in the trunk to the CTEK 3300 all the time (except when driven). Problem solved. Do not waste any money on the stealer.Thank you.

AMGfan

+1

Benz-O-Rama

Agree with the above. I drive my SL600 maybe once a week during the cold months. If it's not connected to my battery tender, I'll get the same messges. Luckily, my car has an MB one, permanantly hard wired.

yeezer1

Thanks everyone!

sifis

You will have to replace the battery in the trunk first, then follow the rest of the steps.

NCE500

My car started displaying the "no consumer electronics" more frequently this winter, more bad weather, and resultant less driving probably also made it more apparent.

Last year the car could sit 2 weeks without the message or symptoms. This winter, that window had reduced itself to about 5 days. I had my indie replace the rear battery, no message or symptoms since. Better to have a shop with Star do the swap as disconnecting the battery will cause several codes that should be cleared.

The net is that rear batteries in the 2004 - 2006 cars are nearing end of life, depending on climate, how the car has been used, etc. I'm sure these cars never did this so frequently when new.

The OEM MB rear battery runs about $200, and add a little for install, money well spent IMO.

AMG903L

Part number for the MB hard wired tender? I need one if it isn't way more than a CTEK.

04sl55mb

It's exactly the same part. CTEK makes the part for MB and MB jacks the price up. CTEK is the way to go.

AMG903L

CTEK isn't hard wired like the one in the SL600 picture. I don't think MB makes that one anymore. I got desperate and went to the corner auto store and bought a Schumacher XCS15. It looks like a nice unit for $50 but I think I'll order a CTEK 7200 and return the Schumacher XCS15 when it comes in.

theunderlord

I just bought the battery tender jr. I too only drive mine one or twice a week, short distances.
Mine could sit no more than 5 days and it would be dead. Problem solved for 40 bucks.

AMG903L

This looks like a good one if you want to hard wire one in the trunk. It only charges AGM batteries.

AMG903L

My car battery was at 82% when I hooked the charger up. After an overnight charge everything worked but still had the Key Not Recognized message and I had to use the key to start it. I replaced the two 2025 batteries in the key and everything was good to go. I replaced the key batteries about a year and a half ago so I will replace them every Halloween from now on.

SL600Mojo

If you end up needing a battery - Autozone carries AGM batteries and installed it's about $150 versus the much higher cost of the dealer battery. The front battery different story - had to replace it and dealer was the only place I could find one. But it's cheaper than the AGM one that runs the consumer electronics.

AMG903L

BatteriesPlus has both in stock. I spent the extra cash and bought Braille Endurance Batteries online. The main and the front batteries are both AGM.

Rear Main = B10049

Front Backup = B14115

rune solem

The original front battery in my sl 55 is a standard one, not AGM.

I reckon the sl 600 have the same standard battery?

Maybe the E55 is different, or it has been upgraded by another owner?