Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
2008 caddy DTS having it's way with me. Battery goes dead intermittently. It has been to Caddy dealer 2x & they gave up on it. New battery twice. Very little[less than .25v a/c ripple from alt]. Using a graphing multi-meter I have about 8-12 milli amps. However when graph is switched to digital, min/max set, in the time span of 2-3 hrs I have recorded as much as 225 milliamps. Last night, batt volts @ 12.6. This morning, batt volts @ 7.1. Again with the min/max set all day, takes about 3 hrs to record 200-225 max milliamps. Anyone point me in a direction? Thanks in advance. Also, less than .1 volt drop on pos & neg main cables.
UPDATE- Disconnected lead to rear fuse block & now max milliamp draw over 8 hrs is staying below 40 mA. Removed all fuses powering bcm, re-connected rear fuse block & draw now still below 40 mA. Certainly appears to be bcm intermittently waking up & drawing battery dead. Opinions? Suggestions?
Even allowing for damage to the battery from the constant discharging-recharging it is suffering I think it would need more than the intermittent currents you are finding to go from 12.6 to 7 v overnight. I think you are looking at drain through a power circuit rather than electronics.
I have seen alternators that appear to work perfectly in voltage test but have so much leakage they will drain a battery in a few hours, in that case the clue was a fairly large spark when I disconnected or reconnected the battery.
" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)
Would that type of alternator issue show up on the a/c ripple test? This one seems to stay at .25v a/c peak to peak. Also put a new battery from stock just for test purposes, left all bcm fusus out for weekend. Will report back on Monday with my findings.
OK Monday morning & Caddy battery was @ 13.0 v after being connected all weekend with just bcm power fuses pulled. Certainly seems to point to bcm as any other time battery has been hooked up for more than 2 days resulted in dead battery. Any suggestions or thoughts are very much appreciated.
Topic Author
