1991 MITSUBISHI MONTERO oil

drivers. They typically require injector circuits
with a total leg resistance with less than 12 ohm.
NOTE: This example is based on a constant power/switched ground
circuit.
* See Fig. 3 for pattern that the following text describes.
Point "A" is where system voltage is supplied to the
injector. A good hot run voltage is usually 13.5 or more volts. This
point, commonly known as open circuit voltage, is critical because the
injector will not get sufficient current saturation if there is a
voltage shortfall. To obtain a good look at this precise point, you
will need to shift your Lab Scope to five volts per division.
You will find that some systems have slight voltage
fluctuations here. This could occur if the injector feed wire is also
used to power up other cycling components, like the ignition coil(s).
Slight voltage fluctuations are normal and are no reason for concern.
Major voltage fluctuations are a different story, however. Major
voltage shifts on the injector feed line will create injector
performance problems. Look for excessive resistance problems in the
feed circuit if you see big shifts and repair as necessary.
Point "B" is where the driver completes the circuit to
ground. This point of the waveform should be a clean square point
straight down with no rounded edges. It is during this period that
current saturation of the injector windings is taking place and the
driver is heavily stressed. Weak drivers will distort this vertical
line.
Point "C" represents the voltage drop across the injector
windings. Point "C" should come very close to the ground reference
point, but not quite touch. This is because the driver has a small
amount of inherent resistance. Any significant offset from ground is
an indication of a resistance problem on the ground circuit that needs
repaired. You might miss this fault if you do not use the negative
battery post for your Lab Scope hook-up, so it is HIGHLY recommended
that you use the battery as your hook-up.
Right after Point "C", something interesting happens. Notice
the trace starts a normal upward bend. This slight inductive rise is
created by the effects of counter voltage and is normal. This is
because the low circuit resistance allowed a fast build-up of the
magnetic field, which in turn created the counter voltage.
Point "D" is the start of the current limiting, also known as
the "Hold" time. Before this point, the driver had allowed the current
to free-flow ("Peak") just to get the injector pintle open. By the
time point "D" occurs, the injector pintle has already opened and the
computer has just significantly throttled the current back. It does
this by only allowing a few volts through to maintain the minimum
current required to keep the pintle open.
The height of the voltage spike seen at the top of Point "D"
represents the electrical condition of the injector windings. The
height of this voltage spike (inductive kick) is proportional to the
number of windings and the current flow through them. The more current
flow and greater number of windings, the more potential for a greater
inductive kick. The opposite is also true. The less current flow or
fewer windings means less inductive kick. Typically you should see a
minimum 35 volts.
If you see approximately 35 volts, it is because a zener
diode is used with the driver to clamp the voltage. Make sure the
beginning top of the spike is squared off, indicating the zener dumped
the remainder of the spike. If it is not squared, that indicates the
spike is not strong enough to make the zener fully dump, meaning there
is a problem with a weak injector winding.
If a zener diode is not used in the computer, the spike from

Fig. 2: Identifying Option Symbols
COLOR ABBREVIATIONS IDENTIFICATION
COLOR ABBREVIATIONS








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Color Normal Optional
Black .................. BLK ................... BK
Blue ................... BLU ................... BU
Brown .................. BRN ................... BN
Clear .................. CLR ................... CR
Dark Blue ............ DK BLU ............... DK BU
Dark Green ........... DK GRN ............... DK GN
Green .................. GRN ................... GN
Gray ................... GRY ................... GY
Light Blue ........... LT BLU ............... LT BU
Light Green .......... LT GRN ............... LT GN
Orange ................. ORG ................... OG
Pink ................... PNK ................... PK
Purple ................. PPL ................... PL
Red .................... RED ................... RD
Tan .................... TAN ................... TN
Voilet ................. VIO ................... VI

White .................. WHT ................... WT
Yellow ................. YEL ................... YL









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WIRING DIAGRAM SYMBOL IDENTIFICATION
NOTE: Standard wiring symbols are used on diagrams. The list below
will help clarify any symbols that are not easily understood
at a glance. Most components are labeled "Motor", "Switch" or
"Relay" in addition to being drawn with the standard symbol.
WIRING DIAGRAM SYMBOLS
Views of the symbols used in the WIRING DIAGRAM articles are
in the following graphics. See Figs. 3 through 25.
Fig. 3: Circuit Breaker
Fig. 4: Coil (Internal)
Fig. 5: Connector
Fig. 6: Diode (In-Line)
Fig. 7: Diode (Internal)

WIR IN G D IA G RAM S

1991 M it s u bis h i M onte ro
1991 Wiring Diagrams
Mitsubishi
Montero
IDENTIFICATION
COMPONENT LOCATION MENU
COMPONENT LOCATIONS TABLE








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Component Figure No. (Location)
A/C RELAYS .......................... 4 (C 12), 4 (A-B 15)
A/C SYSTEM ................................. 4 (A-C 12-15)
ALTERNATOR ................................... 1 (B-C 1-2)
ALTERNATOR RELAY ............................... 1 (C 1-2)
AUTO FREE-WHEELING HUB CONTROL UNIT ............. 3 (D 11)
BACK DOOR LOCK SW ............................... 7 (B 27)
BACK-UP LT SW (M/T) ............................. 7 (A 26)
BATTERY .......................................... 1 (A 1)
BLOWER SWITCH ................................. 4 (A-B 12)
BUZZER .......................................... 5 (E 17)
CARGO LIGHT ..................................... 6 (A 23)
CIG LIGHTER ..................................... 3 (E 11)
CLOCK ........................................... 3 (E 11)
COLUMN SW ..................................... 5 (A-E 19)
CRUISE CONTROL SYSTEM ...................... 4 (D-E 13-15)
DEFOGGER ...................................... 7 (C-D 27)
DIAG CONNECTION .................................. 2 (E 7)
DIMMER CONTROL SWITCH ............................ 3 (E 8)
DIR FLASHER ..................................... 5 (C 16)
DIR SWITCH ...................................... 5 (C 19)
DOME LT ............................... 6 (A 23), 7 (A 24)
DOOR LOCK SYSTEM ........................... 6 (D-E 21-23)
DOOR SWITCHES ......................... 5 (D 17), 6 (C 23)
FRONT WIPER SYSTEM ........................... 5 (A 16-17)
FUEL GAUGE UNIT ................................. 6 (C 22)
FUEL PUMP ........................................ 2 (C 4)
FUSE BLOCK .................................... 3 (C 9-10)
HAZARD FLASHER .................................. 5 (C 16)
HAZARD SW ....................................... 5 (B 16)
HEAD LIGHT WASHER RELAY ....................... 5 (C-D 17)
HEATER RELAY .................................... 4 (A 12)
HORN SWITCH ..................................... 5 (E 19)
IGNITION COIL .................................... 2 (E 4)
IGNITION SW ..................................... 3 (A 11)
ILLUMINATION LIGHTS ............................ 3 (D-E 8)
INHIBITOR SW ..................................... 3 (A 9)
INSTRUMENT CLUSTER ............................ 6 (A-D 20)
KEY REMINDER SW ................................. 5 (E-17)
LIGHT CONTROL RELAY ............................. 5 (E 19)
LIGHT SWITCH .................................... 5 (D 19)
MAIN FUSE LINKS ................................ 1 (A 1-2)
METER UNIT ...................................... 6 (E 20)
MPI CONTROL RELAY ................................ 2 (B 4)
MPI CONTROL UNIT ............................... 2 (A 4-7)
NOISE FILTER ..................................... 2 (E 6)
OVERDRIVE CONTROL RELAY .......................... 3 (A 8)