Ok...here we go. First off, I got the "Brake Failure" message about a year ago. I lived with it by just pulling the front battery cable for a minute and it usually would let me drive for a while without the message coming back. It has gotten a lot worse over the past year however. The car has been sitting for a month or so. I just went out today and had a dead battery (which is less than a year old). No big deal. I took it to Autozone and they charged it for free. I got home, installed the battery and when I went into the car to start it, there was a clicking sound coming from under the left side dash. When I turn the key the starter clicks, but it doesn't start. I let the car sit for a while, hoping the clicking would go away, but when I went to start it again it, the battery was dead...again. I'm assuming the cause of the clicking sound drained the battery. I don't know whether the CEM completely went out or if there are relays under the dash that may have gone bad. I'm afraid it is the CEM since I have heard that it is the main cause of the "Brake Failure" message and I really don't want to spend a ton of money to fix it. I'm hoping one of you have had a similar problem and could help. Thanks!

 

I'm not sure how mechanically inclined you are, but alot of the time a bad starter will make a click noise. It also would drain your battery when you turn it over. I always say check the most obvious things first.

 

If the battery is low it will not have enough power to start the car and you will hear the click. I think the battery is still to weak or bad.

 

The clicking happens constantly...even with the key out of the ignition. The auto store tested the battery and said it was fine. The noise is coming from behind the dash where the CEM is. I'm just not sure if it is just a bad relay or if because the other issues, i.e. "brake failure" message, the whole CEM is bad. What I was trying to say (I probably didn't word it correctly) is that with the battery charged the STARTER clicks as is normally should, but the vehicle doesn't turn over. After an hour sitting there, with the other weird ticking happening as it constantly does, the battery is dead. I'm pretty good with cars so I know it's not the starter.

 

My s80 had a bad ground and it would do that from time to time. Have you tried to jump the car using cables and grounding it out on the frame? Also, what codes (if any) are you pulling? That might help.