asicman

Hi Everyone,

I got a problem with using my smart keys and while I have found a great many posts that talk about smart key issues, I have yet to see one that discusses the specific issues I am having. Here is what I know:

Info: 2003 C32 4-Door Sedan

Symptoms: After the car sits for a while 1+ hours the smart key fails to unlock/lock the car. After manually unlocking the car and placing the key in the ignition, regardless of whether I started the car or not, the key will work once again.

Diagnosis:
1. At first I thought it was the batteries in the key so I checked them. I also tried my spare key....the problem persisted with both keys, which points to the problem being in the car.

2. I thought I had an issue with the battery in the car. I had the charging system tested and it seems to be working fine.

3. I thought there could be a draw or short on the battery, so last night I record the battery voltage when I parked the car 12.87V, this morning I went out and checked the voltage to see how much it had been drained but it showed 12.47V.

4. Since the smart key works part of the time, I doubt it's the IR or RF antenna.

My theory:
There is something wrong with the EIS or the receiver in the the car? Has anyone else experienced something like this?

iJimpanzee

There is some faulty logic in statement 4?

asicman

I guess I only meant that if the IR or RF were at fault, shouldn't the keys fail all the time?

I tested to make sure both the IR and RF worked, testing the IR by lowering the windows using the key, and the RF by unlocking the car with the key in my pocket and ir blocked.

nobli

from what u said, i think its the rf transmitter. something is wrong. the reason the key works after inserting in the car, so there must be some type of interference between the 2. it cant be from the car's end because anyone who had their car parked for a couple hours would be screwed so it must be the key. does your spare work without problems?

asicman

that's the weird thing....the same thing happens with both keys!!! Which is why I thought there must be something wrong on the car's end.

nobli

hmm maybe it is from the cars end, but that would require something like this.
after a specified amount of time (1 hour), the car goes into a "sleep" mode. IF thats the case, then yes its on the cars end. if both keys are doing that and its consistently 1 hour after, then i would say it is definitly on the cars end.

asicman

next experiment to try is to let the car sit overnight, go out in the morning with both keys and see if either one unlocks the car....if neither does than I guess it's something in the car

asicman

both keys still dont work