Boomerang32

After the winter stop and an occasional recharge with Ctec, the rear battery still seemed to be low on power.
The red battery sign came on after starting the car.
After a ten minute drive, the battery sign went out and the top could be opened again.
So far so good.
But: both key fobs are not able to activate remote locking anymore.
New batteries in both, IR function checked and ok, red led active on both.
Also: no blinking signal lights when pushing buttons.
Open/close buttons on the dash work, button “open trunk” works, so the PSE must be ok. (Dry trunk floor, seal below rear window repaired years ago)
Soft close trunk, works as it always did.
Seems the car does not recognize the RF/IR signals of the keys anymore.
Also found no defect fuses till now.

please respond if you have any idea in wich direction to look for a solution.

MBCO

Have you checked fault codes via OBD? Do you have access to Mercedes electronic diagnostic tools? HOW old are your batteries? Intermittent ctek charge may not be enough to keep battery fresh. Low battery conditions can create various issues in r230s. perhaps a restart using proper battery disconnects procedures would clear intermittent faults created. upon restarting fault occurring would enter fault codes as current, which will give clues? Trunk battery ground off first. Then disconnect front battery. Wait 15 minutes. Reconnect front then rear. Restart engine. Search forum on battery replacement procedures to double check my from memory notes. If battery is more than 5 years old, replacement is in order.

Boomerang32

Thanks for your reply MBCO!
I only have a very basic diagnostic tool for engine failures, no Star.
Rear battery only two years old, Bosch AGM.
Already disconnected both batteries ( in the correct sequence) for one night, next morning everything the same after hooking up first front and then rear.
Some extra info; When I first started the car, everything seemed normal, (except for the red battery indicator) drove to my hobby garage, a 10 miles drive, to wash the car.
After washing the car, problems started; the car would not start anymore!
Was the problem related to water ingress maybe?
Of course the message convenience not available popped up and, not seen that ever before, something about reduced brake power.
I then started shifting the gear lever from park to neutral and back, stil no starter motor action.
Then I started checking some other functions, like windows up and down, seats, mirrors in/out, all good. Gave it another try and suddenly the engine did start and everything seemed ok.
Took the car for a nice drive, top down after the battery signal had gone, everything fine again.
-Only remote locking still not working-
Dash buttons-open close still work, when I start driving, car locks doors automatically, all good.

Yesterday and tonight we had quite some rain, quite common in Holland
This morning I checked SAM housing driver side and passenger side, for water ingress, took away carpet passenger side and floorboard to check if everything was dry; all good.
Checked fuses yet again, all good.
Do not know where to look anymore, will need STAR to get any further with this I am afraid.
(Had contact with BenzNinja already)

Its a 2002 Japan 500SL, bought it with only 35k kilometers, (Checked with star at a dealership)and after two summers including big Italy trips, now at 61k kilometers.
Apart from exchanging the rear battery, I never had any electronic problems before and every module or electronic part looks as if its brand new.
something must have suffered from low rear battery voltage now, I am afraid.

RScott

I don't have any advice, but it might help you get on track to know the components involved. When you press an lock/unlock button on the remote the signal is received by the right antenna amplifier, relayed to the Overhead Control Panel (OCP), and then transmitted to the ignition switch (EIS) over the interior CAN. If the EIS recognizes the key, then it signals the PSE accordingly.

Boomerang32

Thanks Rscott, the OCP also was a suspect indeed, but things get stranger and I doubt the OCP is the problem now.
A few minutes ago, meanwhile its dark in Holland, I tried both keys again, keeping them close to the drivers side door handel and suddenly, the doors locked, alarm active again as if nothing is wrong.
But opening...no way.
That means opening mechanically again and then that annoying alarm will go off

So, VERY occasionally locking succeeds, only when the key is very close to the door handel (ir) , but opening never succeeds, with none of both keys.

MBCO

This is where Star comes in handy. These intermittent items typically can be found with diagnostic routines. For example, on my S-class, the interior door lights change 3 different colors via Command. The rear passenger door only does one (the one I like fortunately). Star says its a bad ground inside door panel. All the work instructions to remove the door panel, and repair. (i have not done it yet). Benzninja helped me, his service is included with the package.

For what its worth, you have a very early R230, and Japanese version as well. Your software probably has never been touched. Many updates have solved software issues over the years. My cars have all been updated, running better than when I purchased.

BenzNinja

iTrader: (4)

we will find the problem easy with Xentry
don't worry

Boomerang32

Flabbergasted! Wanted to check the antenne amp left, under dash. Took it out to check wiring and smd capacitors. If I understood correctly, this unit was crucial for remote functions, recieving the left top windshield antenne signal for remote central locking. Now that
it is outside the car, suddenly remote works again, even from a greater distance. Who can explain?

Boomerang32

My guess now: The information on "HehlHans" is not completely correct.
Presumably they switched L/R in the description of the several parts that are involved with remote locking.
The left amp, that is outside the car now, can not be the one responsable for directing FM/TV and remote signals, since remote works again.
Question that remains; why did remote stop working after a low rear battery and why did it start working again after being connected to a fresh battery for a few days?
Detoriated capacitors in some modules involved maybe?
.

Boomerang32

Ok, the info @ Hehlhans seems to be correct for a lhd version.
BUT: my car is a Japan version and the antennas in the windshield are mirrored compared to the picture in WIS/@Hehlhans website.
So the RF antenna is at the passenger side of the windshield in my car, while it’s normally left in a lhd car.
One would presume that the RF antenna would always be at the drivers side of the car though.
Strange Japanese version.....lhd car with a rhd windshield.

BenzNinja

iTrader: (4)

Japan is a problem since years as for some reasons they are using their own command hardware in the cars on many models
that is why in many cases there is no way to convert a Japanese Command system to Euro or USA
but there are many cheap parts all over ebay

Boomerang32

Finally solved this issue. Bad soldering at the smaller 20 pin chip on the passenger side antenna amp. Checked signal from amp to overhead control module at te grey/yellow wire with a scope and saw changes when pressing that chip. After re soldering its contacts, everything works like a dream now.

Oldmenscar

as you all know that batteries for MB are very expensive but if you go on youtube on how to make your old batteries last for ever. It will teach you how to do it and keep recharging your old batteries and you won’t have to ever buy new ones anymore