anskuotas

Hy all, have a problem here. Long story short. I had a flat battery in the trunk for electrical equipment. I opened car manually start normal, went to garage and checked rear battery it was hot and some acid around, guess battery shorted inside. Pull ot out and replaced with a new one. Went for a couple hours drive in highway, after about 1.5hour drive stopped for a smoke, came back to a car and it didn't start looks like starter battery flat, jumped positive wire to starter battery and trunk battery, started right away. Finished my trip, shutdown the engine and tried to start no luck. Charged the front battery manually and been driving for a one week until it got flat again. Connect MB Star diagnostic tool, went to actuations and activated battery coupling relay, connect multimeter at this point it was charging, but as soon as i turned off star it opened again. Was reading around and found that starter battery is charged by some other module next to the trunk battery. Some dc/dc charging converter. Can someone point out what to check next.

gfmerc

did you find out what this was, i charge mine and it soon drains, i put multimeter on it and it is not receiving charge from the alternator, whereas the starter battery in the ending bay is. This battery is draining when the car is off and not charging when on. Is there a faulty relay somewhere that is discharging

Gamecocks

Having same exact issue. Have been charging the trunk battery starter battery good. Going to take it to Autozone tomorrow and have them test the rear battery... but still not making sense why its not getting voltage. Almost want to put a jumper cable between the batteries lol.. wont be doing that. I did read that someone did that to jump the car one time when Starter battery was dead..