Brutu5

Hi Guys,


1st time poster here. I have a query relating to starting/stopping the car using keyless go.

Right so, opening and locking the car works fine. No problems whatsoever there. But sometimes starting and stopping the car doesnt work. I've noticed that it does this mainly in the morning or if the cars been off for a couple of hours. Usually after the first start of the day using the key in the ignition, using keyless-go to start and stop the car works bang every time for the rest of the day.


Is it possible that it's a battery voltage problem? I've only just got the car and I don't know how old the battery is. I did notice that it wouldnt start at 12.4v and it did at 12.8v. Is this relevant?


Any help would be great, I just got the car and it's my 1st Merc after a string of BMWs. I must say, it's considerably more lux than the beemers. I just want everything to function

Cheers in advance

Brutu5

I just did that an hour ago. Won't be able to tell for sure until tomorrow morning. I just want to see if the battery voltage is an issue that'll affect the start/stop keyless function but not the opening/closing function.

Brutu5

Seems to be worse with the new battery. The old one was a 100ah and the new one is an 80ah. Thinking slapping in a 120Ah would solve the problem.

Theories anyone?

Kevwood

I'm kind of having a hard time imagining that this is a battery issue. My reasoning behind this thought is that the car is recognizing the key, it is allowing you to enter the car, it is not flashing the message "key not recognized" when you try to start the car. Even when the batter in my key fob was so weak that it wouldn't lock/unlock the doors with the manual buttons, it still worked as the keyless-go fob and was recognized by the car. Eventually the battery gave up the ghost but I was given the "key not recognized" message.

It's a Mercedes so who knows what electrical gremlin this one is

Brutu5

Thing is with this battery, if I go for a drive turn off the car with the key and switch it on wIth keyless, it starts every time and a few mins after that. Could it be an electrical leak ?

Kevwood

I really dont know pal, it's very odd what is happening. The 209 is notorious for electrical gremlins, I've had to hard-reset mine a few times - luckily it was solved the issues without fail.

Brutu5

What do you need to do to hard reset? Is it a dealer thing?

Kevwood

Nope, just disconnect your battery for a good 20-30 minutes. Yeah, sounds like a very Shade-Tree Mechanic thing to do on a German luxury car but it works.

Brutu5

Worth a shot! I'll do it now then. Thanks Kevwood

Rudeney

Also, it could be the battery in the key fob. When using the key in the ignition switch, the fob's battery is not used as the EIS supplies inductive power, but of course the RF functionality of KeylessGo needs the fob's battery to work.

Brutu5

I changed the batteries in the key yesterday aswell. No difference. I'm thinking it's either an electricity leak or I need a 120Ah battery.

Got an appointment with a Merc specialist tomorrow. Fingers crossed its something stupid.