E39 M5 starting problems
I have scoured the internet and not come up with much hopefully someone can help.
I got up this morning went out to the car and my trunk and doors opened just fine. When I went to start the car I got about a quarter turn on the ignition and lost all power in the car. I hooked up my booster thinking the battery might just be dead let that sit for about and hour and tried starting again now had power in the car but it would not turn over. When I disconnected the booster the power now remained on and checked the voltage at the battery it was reading 12.4V. So I tried to star the car again now with no booster and when I turn the ignition I loose all power again just like I did the first time. I now went back to the trunk to check the voltage again and as soon as I touched my voltmeter to the battery the power came back on. My suspicions are a bad battery though it is only 18 months old and I have had no problems, my starter is dead but that does not explain the total power loss, I have a ground shorting issue? Thanks in advance for the help.