Hello. Something strange is happening to my E55. It started the other day. First, when I tried to start the car with the keyless go, it wouldn't start. Wouldn't even turn over. Tried a few times then all of the sudden it started normal. Weird I thought. Next day, did it again then started.

Yesterday, I hit the unlock button twice as I usually do at night so the fog lights and city lights would turn on. When I did that, the passenger side city and fog light where flashing. The drivers side was fine. I got into the car and started it. That's when all hell broke loose on the dashboard. White brake light came on, red battery light, the cluster was turning on and off. So I shut the car off. Restarted it and everything was normal. Does this sound like a loose ground or has anyone has this issue before? Any help would be appreciated.

 

First thing to do is to pull up the USB bus voltage on the instrument cluster.

Turn key to position 1, set instrument cluster to "mph", press reset button 3 times rapidly, voltage should come up in the display. Should be =>12.1 volts. If less, your main battery can't supply the electronics. While in there, check out the auxiliary battery.

Once the main battery is confirmed, then you can begin digging deeper. While you are at it, change out the batteries in the key fob. I find that using Keyless-Go tends to run down the batteries in my key fob faster than having it in the EIS.

 

Thanks for your help. I checked and the battery is at less than 12v when I checked it. When I start it the battery dips into the low 9s while it cranks. Today shortly after I started driving, the passenger headlight and fog light started blinking, the heat turned off and on, the sbc and battery light, as well as the esp came on. So this is all caused by the battery you think?? What is the oe battery specs so I can compare to the new battery that I will be getting??

 

Replace the main battery. You want AGM 900 CCA. Remove key fob from ignition; if Keyless-Go keep key fob minimum 2 meters from car when disconnecting old battery and connecting new battery. Reset windows and sunroof and you are good to go. FWIW, your car has approximately 32 distributed digital control modules and they go bonkers with low voltage.

 

If your alternator is working, it should jump up around 14v after you start it.

 

Yes, its at about 13.8-14.0