Weard problem
 

I did a search for this and I didn’t see anyone with the same problem! Last week my check engine light was on with the following codes 0720, 0500, 1605, 0600. Well this week it’s gone! However a new one has come up, When I try to unlock the car I have to get right up to it and I still have to press the unlock button a few times before it opens, the garage door opener, sunroof, sun visor light and another thing have stopped working. I know I’ve checked the fuse and it’s good. I’ve also checked the battery voltage on the AC unit and it shows 11.5~8 with the car off and 13.2~3 with it on. Any ideas anyone? Thanks for all the input in advance.

On your E class at least, the battery in the key powers an infared transmitter to lock/unlock the doors. Try changing it.

Not sure about your other issues. Has the K40 relay ever been replaced?

Not sure what the K40 relay is but no it has not. As far as the key it has a good battery! I just don’t think its that because everything started all together.

As far as the codes you listed, I did a little research for you. Found this at IATN:

"It was suggested to me in a previous request for assistance
here that the wiring and connections at the antilock valve
was suspect since it lives under the washer tank. I have
yet to find a problem there, just really easy to break the
washer tank."

It turned out that the real problem was the ESP module was bad. But since you have more problems I would look for bad grounds and corroded plugs/connectors.

Pete

How do you know its good and not weak?

Powering the infrared for the doors is the ONLy function of that battery.

K40 provides power to numerous electrical systems. They usually begin to cause intermittent or permanent electrical faults after 5-8 years as the solder pathways on the circuit boards deteriorate.

I would expect a charging voltage ~14.2V, and at 11.9V, an idle battery is fully discharged. Probably a weak alternator or belt slippage.

Steve

Well I just replaced the car and key fob battery. However the sunroof, Dimming function on rear view mirror, interior front light, mirror lights garage door opener still don’t work oh and I still have to go right up to the door to lock and unlock the car. I’ve checked for corrosion under the water tank and it looks good. Is there any way of checking the K40 relay?

Thanks!