My 2004 E55 Red battery message

[smoothcoupe]

Hi all. Cars been parked up for 3 weeks due to dodgy crank sensor and was abroad and busy with work n stuff... last week I approached the car and pressed the remote managed to open the car greeted with reduced brake power in red and car wouldn’t start. I then proceeded to try and get into boot to gain access to boot to the battery, I then changed the crank sensor... yesterday I managed to get power to the car via fuse box and gain entry to the boot and charged the battery overnight... (only 6 month old, bought from main dealer, Changed auxiliary one at the same time also from main dealer) when I put battery back on today initially no problems at all, no malfunctions. I drove to the gym had a good workout and when I returned to the car and opened it, the temp display was reading 85degrees and it wouldn’t start with the keyless go but started fine with the key reading 14volts on the dash, other messages were brake service visit workshop, red battery warning and convenience features not available. No wipers and headlight constantly on but only on the drivers side. I came home had a shower and went back to the car and no problems at all correct temp readings and everything worked fine, went out a bit later and same again but on the dual carriage way. Convenience features available again and everything worked fine. Went for some fuel jumped back in and holy crap same exact same thing 85 degrees red battery and no convenience features.. any ideas.???? I’m thinking something to do with auxiliary battery relay any ideas chaps.. voltage at main battery is 12.6 and 14.4 running and 12.9 on aux battery... come on experts give me some clues!! Thanks..

 

[Dodipops]

Possibly the rectifier on the back of the alternator starting to fail, just coincidence it was 14.4 when you happened to check it. Or maybe battery control module. There will probably be a software update for your bcm, might just need that and a reset.

 

[smoothcoupe]

Thanks. Is it only the dealer who can do the software update. I’ve just ordered the MB2 icarsoft diagnostic reader to pull any codes. I do have a cheap autel one that did read the crankshaft sensor fault. Tried that one and zero codes!

 

[Gbrowncls55]

My wifes sl does this sort of thing on an entirely random basis. And has done for two years. Ffter many attempts to sort it we have narrowed it down to the battery control module or the ingnition switch. So they are next. Its been on star.

 

[smoothcoupe]

My wifes sl does this sort of thing on an entirely random basis. And has done for two years. Ffter many attempts to sort it we have narrowed it down to the battery control module or the ingnition switch. So they are next. Its been on star.

Thank you!

 

[Dodipops]

No you can get software updates from independents that have the capability.

 

[smoothcoupe]

No you can get software updates from independents that have the capability.

Once again cars been good as gold today no malfunctions. But sure it will come back. Last time it happened it just gradually disappeared until I started messing around again after battery ran flat... weird like it’s got a mind of its own.... spooky car..... a damn quick spooky car LOL..