voltage or resistance values using a DVOM while attempting to
reproduce conditions which may cause intermittent fault. A status
change on DVOM indicates a fault has been located.
When using a DVOM to pinpoint faults, monitor voltage reading
with ignition on, or vehicle running. Ensure ignition is in OFF
position or negative battery cable is disconnected when monitoring
circuit resistance. Change in ohmmeter reading during test procedures
indicates area of fault.
TEST PROCEDURES
Intermittent Simulation
To reproduce conditions which cause intermittent fault, use
the following methods:
* Lightly vibrate component.
* Heat component.
* Wiggle or bend wiring harness.
* Spray component with water.
* Remove/apply vacuum source.
Monitor circuit/component voltage or resistance while
simulating intermittent fault conditions. If vehicle is running,
monitor for self-diagnostic codes. Use test results to identify a
faulty component or circuit.
input device usage on specific models, see appropriate wiring diagram
in M - WIRING DIAGRAMS.
Air Conditioner Switch
When A/C is turned on, signal is sent to ECU. With engine at
idle, ECU increases idle speed through Idle Speed Control (ISC) motor.\
Airflow Sensor
Incorporated in airflow sensor assembly, airflow sensor is a
Karmen Vortex-type sensor which measures intake airflow rate.
Intake air flows through tunnel in airflow sensor assembly.
Airflow sensor transmits radio frequency signals across direction of
incoming airflow, downstream of vortex. Intake air encounters vortex,
causing turbulence in tunnel.
Turbulence disrupts radio frequency, causing variations in
transmission. Airflow sensor converts frequency transmitted into a
proportionate electrical signal which is sent to ECU.
Airflow Sensor Assembly
Mounted inside air cleaner, incorporates airflow sensor,
atmospheric pressure sensor and intake air temperature sensor.
Atmospheric (Barometric) Pressure Sensor
Incorporated in the airflow sensor assembly, converts
atmospheric pressure to electrical signal which is sent to ECU. ECU
adjusts air/fuel ratio and ignition timing according to altitude.
Coolant Temperature Sensor
Converts coolant temperature to electrical signal for use by
ECU. ECU uses coolant temperature information for controlling fuel
enrichment when engine is cold.
Crankshaft Angle & TDC Sensor Assembly
Assembly is located in distributor on SOHC engines. On DOHC
engines, which use Direct (or Distributorless) Ignition System (DIS)\
,
assembly is separate unit mounted in place of distributor. Assembly
consists of triggering disc (mounted on shaft) and stationary optical
sensing unit. Camshaft drives shaft, triggering optical sensing unit.
ECU determines crank angle and TDC based on signals received from
optical sensing unit.
Detonation Sensor (Turbo Only)
Located in cylinder block, senses engine vibration during
detonation (knock). Sensor converts vibration into electrical signal.
ECU retards ignition timing based on this signal.
Engine Speed (Tach Signal)
ECU uses ignition coil tach signal to determine engine speed.
Idle Position Switch
On all DOHC engines and Sigma 3.0L, idle position switch is
separate switch mounted on throttle body. On all other models, idle
position switch is incorporated in ISC motor or throttle position
sensor, depending on vehicle application. When throttle valve is
closed, switch is activated. When throttle valve is at any other
position, switch is deactivated. This input from idle position switch
is used by ECU for controlling fuel delivery time during deceleration.
Ignition Timing Adjustment Terminal
Used for adjusting base ignition timing. When terminal is
grounded, ECU timing control function is by-passed, allowing base
timing to be adjusted.
Fig. 2: Detection Switch Testing Locations (Montero)
Courtesy of Mitsubishi Motor Sales of America.
REMOVAL & INSTALLATION
Removal
1) Remove negative battery cable. Remove transfer case skid
plate (if equipped). Scribe alignment marks and remove both drive
shafts. Drain oil from transfer case. Disconnect wiring harness from
back-up light switch, all 4WD switches and any other electrical
connectors (if equipped).
2) Disconnect speedometer cable from drive. Unclip cable from
case. Place transfer case shifter in "2H" position and transmission in
Neutral. Remove 6 bolts holding control lever assembly. Remove control
lever assembly and gasket.
3) Remove select plunger bore plug at right side of case.
Remove select spring and plunger. Remove change shifter spring pin.
Remove change shifter. Remove transfer case mount. Remove 4 bolts and
2 nuts holding transfer case to adapter. Remove transfer case from
vehicle.