Ignition off draw refers to power being drained from the battery with the ignition turned off. A normal vehicle electrical system will draw from 5 to 20 milliamps. This is with the ignition in the OFF position, and all non-ignition controlled circuits in proper working order. A vehicle that has not been operated for approximately 20 days, may discharge the battery to an inadequate level. Battery drain should not exceed approximately 20 MA (20 milliamps = 0.020 amps). The 20 MA are needed to supply PCM memory, digital clock memory, ETR (electronically tuned radio)
and Security Alarm memory.
Excessive battery drain is caused by items left turned on, internally shorted generator, or intermittent short in wiring. If IOD is over 20 milliamperes, the defect must be found and corrected before replacing a battery. In most cases the battery can be charged and returned to service.