My key fob stopped unlocking doors and trunk. It also wouldn't allow to start unless the fob was plugged into the dash port. While it was plugged in car would start and run but then randomly shut off. Engine light came on. Code was for Fob lost connection to immobolizer. But the car still starts and will run. While driving the car engine runs but instrument panel goes off and gauges go to zero for about 3-5 seconds then start back up again. This happens over and over while moving and engine running. I have replaced battery with 2 new batteries reading at full levels. The dealership is saying the key fobs are not sending out signal. My questions is then why would the car start? They want me to buy new key ($300) and if that doesn't fix it a new immobilizer ($700). Should I be concerned with replacing all this if there is a signal being received to start the car even though they say there isn't. Anybody have any experience with this please respond.

 

do u only have one key? if the second key works fine then u can rule out immobilizer probably. also i would suggest replacing batt with the same one that one in the key when it worked. for me the fob didnt like some batts. and u can buy a new oem from ebay for like $40 and have the dealer program it for $90.

 

Considering the instrument panel symptoms associated with the key fob problem, i think the problem is from BCM.
Not from the key fob.
Whatever happen to the key fob, the instrument panel should NOT be affected in any way.

 

i would also start identifying the issue by using your spare key fob. if there is no problem with the secondary key fob the problem you are having is with the original key. these keyless remote fobs have built in rolling codes and you may have reached the max number of codes and the immobilizer is not recognizing it properly. its definitely not the batteries in the remote since you already replaced 3 of those.