seattleblue

Hoping to get a quick a quick YES or NO answer to this. Background is that transmission on 2004 E60 545 recently went into limp mode (no reverse). Towed to dealer, they replaced battery saying it was only a low voltage protection due to dead battery. OK everything fine except a few blocks away noticed that what ever they did blew out the radio (M-ASK), AMP relay, what ever? So it scheduled to have it diagnosed to fix. BUT the bigger issue is that a couple days later the vehicle again will not go into reverse. Volts on resting battery under 12, so I notice I hear amp fan running and fiber optic is lit. Charge the battery and remove radio and amp fuse, next morning the battery is at 12.6 volts. So my question is... the fuse for the radio; should it be showing 12 volts when car is off and key removed? I know traditionally in an old school radio hook-up the radio has a constant feed to keep memory and a second feed which is circuited off when either the vehicle is turned off or a delayed relay that switches off after a few minutes even with key in and car off.

1600

wrong section

seattleblue

Yes new to forums, my apologies

Only Bimmers

Hey Seattle,

Do this, get an analog multimeter at your local sears, harbor freight, etc. Run the car and put the meter on the battery terminals and read the voltage. If it is below 13.x volts you have a charging issue. Also a second test is watch the needle on the multimeter and see if it fluctuates back and forth a bit, that is another way to tell if the rectifier is going out.

The car has an auto off function built into it i believe after 15 mins of no interaction. So no you should not have voltage. But! These cars go crazy with low voltage, really strange behaviors. Start with your charging system as i stated and save allot of $.

Although this is the M5 section, as you stated you are new and it isn't a big deal. No worries, we are here to help.