Central locking & AM radio do not work after battery disconnection.

[Sphinx]

Good morning guys.

I have a 2002 C200 Kompressor, Sportcoupe in manual.

Epilogue: I have only posted to this site once before, which was down to my engine light being on etc. It turned out that I had an issue with my Mass Airflow Sensor, which I replaced on Sunday. In replacing the sensor, I followed all safety procedures as outlined by a few mechanics etc, which included disconnecting my battery to safely work inside the car.

I would just like to emphasise that I am a complete idiot when it comes to cars. I learn what I learn just via forums, online help, etc. Please have patience if you suggest I tear out some bodywork to get at a receiver I've never heard of haha, it's a little beyond me (although I'd love to try).


My issue: After disconnecting my battery, performing the swap for my MAF sensor, and reconnecting it, I am now faced with an electronics/re-synch error. This was expected. My first notice was the ESP needing reconfiguration, which I did according to the manual by turning the steering far left then right. I also reconfigured my electric windows the way the manual suggested. My problem, is that my key fob no longer locks and unlocks my car via the two buttons on the remote. I am having to use my emergency key to get in and lock it instead. This is so tiresome, especially with company, or wads of shopping.

Things I've tried / noted:

• 
  First and most obviously, I tried what the manual suggested to re-synchronize the key: Popping the key into the ignition, turning it to click 2, and back out. Needless to say, nothing is ever this easy.
  
  The IR on my remote does work. The red LED lights up when buttons are pressed, and I am able to see my IR beam through a digital camera when buttons are pressed.
  
  The IR on my door however does nothing when I am trying to open it from a few inches away. No reaction. I do not have a keyhole, nor IR receiver on my passenger side to try.
  
  So far it looks as though neither the IR nor RF are responding to the key buttons, from any side of the car. Passenger, boot, driver side.
  
  I have tried a gazillion combinations of button presses, and insertions to the ignition phase 2 as suggested by many others with similar issues, including holding the lock button followed by pressing unlock 5 times, reinserting it, holding the button near the IR receiver outside, jumping in the car quickly and inserting to ignition etc.
  
  Upon reading up tirelessly on similar issues online, it has occurred to me that I may have a faulty RF receiver (though I can't explain the IR issue with this). I checked my AM radio, and have nothing on any frequency, just white noise and infinite scanning. I think I'm getting somewhere with that one. A few have replaced and mentioned a fuse responsible for these electronics (Fuse #8, amp 7.5?)

I hope I've been as informative as I can be here. If this does sound like an RF issue, could it simply be that I have blown a fuse from the battery reconnection? If so, where do I find this exact fuse on my car to replace it, and is there just one fuse responsible for RF as well as the central locking? As I believe there are around 3-4 fuse boxes dotted about or something similar.

Once I try the fuse, am I right in saying that if it still doesn't work, I am looking at a new RF receiver near my back window? (Expensive, least desirable option I'm sure).

I just want to reiterate that this issue has only started after disconnecting my battery, it would surely have to be some major coincidence or issue if my entire RF packed in after that, rather than a simple fuse replacement, wouldn't it?

I thank you all in advance, even just for making it through such a long post. I like to be thorough.

 

[richard]

I think you have 2 faults.
a) an issue with the antenna amp that is used to pick up AM and remote control
b) Some issue with the IR pickup on the door which you've never noticed as you've never needed them to work before

I'd start by checking fuse 8 in the rear SAM fusebox (in the boot) which is a 7.5Amp fuse which feeds the antenna amplifiers. If thats OK, its probably the antenna amp that has packed in but i'd check the power at the antenna amp for completeness myself :-(

Richard

 

[Sphinx]

Thanks for that Richard, I'm glad I've had somewhat of a confirmation on what I'd spent a while scanning the internet for.

Thanks also for directing me to the SAM fusebox in the boot, as I was unsure which one it would be. I'll start with that first, the cheapest possible solution.

As for the IR, I'm not totally miffed about that at the moment. I never used it before, and probably won't in future. Seems fairly odd to me that the option is even there on these cars, given the RF functionality, but what do I know.

I will aim to replace the fuse this week and try that. Quick query though Richard: You mention checking the power at the antenna amp for completeness? How do you mean, and is this something a novice like myself could do or would I need a specific tool/diagnostic (or person) to do this for me?

 

[richard]

Hi
You'd need to dismantle one of the covers over the C pillars at the rear and use a multimeter to check there is power there. The chance of the cable failing between there and the fusebox is just about zero, but i'd do it before replacing the antenna amp as a matter of completeness, because even low probability things do happen !

R

 

[Sphinx]

Thanks again, and yes you're right. Low probability things definitely happen.

I may be right in saying that it's a low probability thing happening right now, as it was caused by something as seemingly innocent as disconnecting the battery as I fitted an irrelevant part. *Sigh*.

We'll see how I get on this week.

 

[Dec]

As it’s a 12 year old car, its worth testing the alarm after you replace any blown fuses, for a W202 in the link, simelar to a W203… http://www.mbclub.co.uk/forums/electronics/169666-w202-how-test-car-alarm.html

The alarm siren has rechargeable batteries inside, the don’t like being deprived of a 12v power supply when the get old, the can get very irritable and can cause all sorts of faults.

Dec