Mitsubishi Montero (1998+). Manual - part 251

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

terminals. See Fig. 1. Select 10-amp scale.

         3) Turn off all electrical accessories. Turn off interior

lights, underhood lamp, trunk light, illuminated entry, etc. To avoid

damaging ammeter or obtaining a false meter reading, all accessories

must be off before turning test switch knob to OFF position.

         4) Turn test switch knob to OFF position to allow current to

flow through ammeter. If meter reads wrong polarity, turn test switch

to ON position and reverse leads. Turn test switch to OFF position.

Observe current reading. If reading is less than 2 amps, turn test

switch to ON position to keep electrical circuits powered-up.

         5) Select low amp scale. Switch lead to the correct meter

position. Turn test switch to OFF position and compare results to

normal current draw. See the GENERAL MOTORS PARASITIC LOAD TABLE. If

current draw is unusually high for the vehicle’s overall electrical

system, remove system fuses one at a time until current draw returns

to normal.

         6) Turn test switch to ON position each time door is opened

or fuse is removed. Turn switch to OFF position to read current draw

value through meter. When the cause of excessive current drain has

been located and repaired, remove test switch and reconnect negative

battery cable to the negative battery terminal.

Fig. 1:  Connecting Kent-Moore Disconnect Tool (J-38758)

Courtesy of General Motors Corp.

GENERAL MOTORS PARASITIC LOAD TABLE (MILLIAMPS)

                                   Normal     Maximum    Time-Out

Component                           Draw        Draw    (Minutes)

Anti-Theft System  ................  0.4  ....  1.0  .......  ...

Auto Door Lock  ...................  1.0  ....  1.0  .......  ...

Body Control Module  ..............  3.6  ...  12.4  ........  20

Central Processing System  ........  1.6  ....  2.7  ........  20

Electronic Control Module  ........  5.6  ...  10.0  .......  ...

Electronic Level Control  .........  2.0  ....  3.3  ........  20

Heated Windshield Module  .........  0.3  ....  0.4  .......  ...

HVAC Power Module  ................  1.0  ....  1.0  .......  ...

Illuminated Entry  ................  1.0  ....  1.0  .........  1

Light Control Module  .............  0.5  ....  1.0  .......  ...

Oil Level Module  .................  0.1  ....  0.1  .......  ...

Multi-Function Chime  .............  1.0  ....  1.0  .......  ...

Pass Key Decoder Module  .........  0.75  ....  1.0  .......  ...

Power Control Module  .............  5.0  ....  7.0  .......  ...

Retained Accessory Power  .........  3.8  ....  3.8  .......  ...

Radio  ............................  7.0  ....  8.0  ........  15

Twilight Sentinel Module  .........  1.0  ....  1.0  .......  ...

Voltage Regulator  ................  1.4  ....  2.0  .......  ...

         INTERMITTENT PARASITIC LOAD PROBLEMS

         Intermittent parasitic lad can occur because of a memory

device that does not power down with ignition off. With an

intermittent parasitic load, battery draw can be greater than 1.0 amp.

To find and intermittent problem requires that an ammeter and

Disconnect Tool (J-38758) test switch be connected and left in the

circuit. See Fig. 1. Road test vehicle. After road test, turn ignition

off and remove key.

         Monitor the milliamps scale for 15-20 minutes after ignition

is turned off. This allows monitoring memory devices to determine if

they time out and stop drawing memory current. The test switch is

needed to protect ammeter when the vehicles is started.

         DIODE CHECK & SOLENOID TEST (GENERAL MOTORS)

Fig. 2:  Diode Check & Solenoid Test (General Motors)

Courtesy of General Motors Corp.

         QUAD DRIVER TEST (GENERAL MOTORS)