PARASITIC LOAD EXPLANATION & TEST PROCEDURES
1998 Mitsubishi Montero
GENERAL INFORMATION
Parasitic Load Explanation & Test Procedures
* PLEASE READ THIS FIRST *
This article is provided for general information only. Not
all procedures apply to all makes and models.
GENERAL INFORMATION
The term Parasitic Load refers to electrical devices that
continue to use or draw current after the ignition switch is turned to
OFF position. This small amount of continuous battery draw is
expressed in milliamps (mA). On Ford Motor Co. and General Motors
vehicles produced after 1980, a typical Parasitic Load should be no
more than 50 milliamps (0.050 amps).
Vehicles produced since 1980 have memory devices that draw
current with ignition off for as long as 20 minutes before shutting
down the Parasitic Drain. When Parasitic Load exceeds normal
specifications, the vehicle may exhibit dead battery and no-start
condition.
Follow test procedure for checking Parasitic Loads to
completion. A brief overview of a suggested test procedure is included
along with some typical Parasitic Load specifications. Refer to the
GENERAL MOTORS PARASITIC LOAD TABLE chart.
TESTING FOR PARASITIC LOAD
INTRODUCTION
CAUTION: Always turn ignition off when connecting or disconnecting
battery cables, battery chargers or jumper cables. DO NOT
turn test switch to OFF position (which causes current to run
through ammeter or vehicle electrical system).
NOTE: Memory functions of various accessories must be reset after
the battery is reconnected.
The battery circuit must be opened to connect test switch
(shunt) and ammeter into the circuit. When a battery cable is removed,\
timer circuits within the vehicle computer are interrupted and
immediately begin to discharge. If in doubt about the condition of the
ammeter fuse, test it with an ohmmeter prior to beginning test. An
open fuse will show the same reading (00.00) as no parasitic drain.
Begin test sequence with the meter installed and on the 10-amp scale.
Select lower scale to read parasitic draw.
TEST PROCEDURE USING TEST SWITCH
1) Turn ignition off. Remove negative battery terminal cable.
Install Disconnect Tool (J-38758) test switch male end to negative
battery cable. Turn test switch knob to OFF position (current through
meter). Install negative battery cable to the female end of test
switch.
2) Turn test switch knob to ON position (current through
switch). Road test vehicle with vehicle accessories on (radio, air
conditioner, etc.). After road test, turn ignition switch to LOCKED
position and remove key. Connect ammeter terminals to test switch
