SLK 200 Multitude of faults!

[trejo]

Hi All,
New here so bear with me!
SLK 200 (2005) No central locking, roof, indicators, main beam, interior lights flash on and off at will, dip beam head lights on all the time, no main beam, no windows, key does nothing (no lock or unlock), fuel guage works when it wants to, no wipers, dash display faulty, SRS stays lit, no ESP, no A/C radio on and off at will, can't get into menu, shows 2 malfunctions, but it runs!
Battery voltage 12.8 constant, rises on running to 13.2 V
all fuses OK, all feeds to fuse boxes OK, leave it running for 3 hrs and eventually it will all come back and no malfunctions!
Runs for a couple of days and all OK, following day go to unlock and we're back at square one!
Vehicle was on a roro ferry for two weeks and when it arrived battery was totally dead, jump start (correct procedure followed) ran fine, but noticed both dipped beam headlights blown................. any ideas???

 

[trapperjohn]

Welcome trejo. Thats quite a list. The roro ferry? Did it stay on top of the water for the whole journey!!
Now I am to car electrics what fireguards are made out of chocholate. But I have picked up a few buzz words! Perhaps start with the Over Voltage Protection Relay (OVP) That is, if a 2005 car has one. My old girls do. Your charging circuit sound ok. I'm sure our techno peeps will be along to sort you out soon. Good Luck with it and again. Welcome to the forum.

 

[trejo]

Thanks for the welcome, hopefully someone has had similar fault! roro = roll on roll off, multimeter at the ready!

 

[BlackC55]

You don't have an OVP.

The running voltage should be 14.4V or there abouts when tested at the alternator. This maybe causing the issue.

 

[trejo]

OK not been able to reach 14.4V at battery, will check output at alternator tomorrow, can't help thinking it's battery/alternator related as opposed to a rear sam unit fault.....

 

[alibally]

I know this sounds daft but do you use the same key all the time or is it ok with the second key. (If you have one) . There can be a fault it the coil inside the key that causes the ignition supply to the front sam unit (fusebox) not to be supplied to it via the can network, and can cause a similar fault to yours. But the car still starts. Try this first and repost please .

 

[tagnut]

Battery or alternator (or both). Get the battery tested with a battery tester (not just voltage) and check the alternator is outputting 14.4V when engine is running.

How old is the battery?