Couple days ago my 2003 e320 was dead... • with no advance warning messages...
• sub zero weather...
• 3-1/2 year old main battery (reads 3v)...
• 3-1/2 year old Aux battery (reads 12.4v)...
ACTIONS 1:
• charged main battery to full charge, took overnight...
• car started... alternator charging at 14.2A...
• car left over night and was dead in morning...
• replaced battery with new (old battery tested at <400cca)...
• Next morning dead...
ACTIONS 2:
• Ammeter in series with negative main battery terminal an disconnected negative lead...
• initial reading 5+DCA...
• After about 10 minutes dropped to 3+Amps...
• after about 1 hour dropped to 2.02A...
ACTION 3:
•Seemed as though an obvious parasitic draw...
• First suspect bad alternator diode...
• easy diode test performed, then bench test.. diodes tested ok...
ACTION 4:
• With car off and key out of ignition noticed a slight air flow from A/C vent...
• simple search 'heater fan runs when key is off' lead to module/regulator on fan was bad...
• Replaced the module and the fan problem is solved...
• found module on-line about $40... (there are several variations, the attached pictures are the of the module in my 2003 e320)
• 1 to 1-1/2 hours to replace... fairly simple...
MUST BE METHODICAL... (many on-line How-to videos.
RESULTS:
• Fan no longer runs when key is removed...
• car started after sitting 18 hours with no malfunction messages...
• sub zero weather...
• 3-1/2 year old main battery (reads 3v)...
• 3-1/2 year old Aux battery (reads 12.4v)...
ACTIONS 1:
• charged main battery to full charge, took overnight...
• car started... alternator charging at 14.2A...
• car left over night and was dead in morning...
• replaced battery with new (old battery tested at <400cca)...
• Next morning dead...
ACTIONS 2:
• Ammeter in series with negative main battery terminal an disconnected negative lead...
• initial reading 5+DCA...
• After about 10 minutes dropped to 3+Amps...
• after about 1 hour dropped to 2.02A...
ACTION 3:
•Seemed as though an obvious parasitic draw...
• First suspect bad alternator diode...
• easy diode test performed, then bench test.. diodes tested ok...
ACTION 4:
• With car off and key out of ignition noticed a slight air flow from A/C vent...
• simple search 'heater fan runs when key is off' lead to module/regulator on fan was bad...
• Replaced the module and the fan problem is solved...
• found module on-line about $40... (there are several variations, the attached pictures are the of the module in my 2003 e320)
• 1 to 1-1/2 hours to replace... fairly simple...
MUST BE METHODICAL... (many on-line How-to videos.
RESULTS:
• Fan no longer runs when key is removed...
• car started after sitting 18 hours with no malfunction messages...
