1998 ISUZU TROOPER controls

8DÐ208 WIRING SYSTEM
Stoplight
General Description
The circuit consists of the stoplight, stoplight switch
(vehicles w/o cruise control), brake switch (vehicles
w/ cruise control).
With the brake pedal depressed, the stoplight switch
or the brake switch is turned on to illuminate the
stoplight. The brake switch controls not only the
operation of the stoplight but also the input of the
cruise cancel signals to the cruise control unit.

8DÐ284 WIRING SYSTEM
Anti-lock Brake System (ABS)
General Description
The circuit consists of EHCU (Electronic Hydraulic
Control Unit), wheel speed sensor, GÐsensor,
stoplight switch or brake switch (w/cruise control),
backup light switch, transmission switchÐ1, 2,
indicator light and data link connector.
EHCU controls brake fluid pressure applied to front
and rear wheels to prevent wheels from locking by
using speed sensor and GÐsensor signals.
Based on wheel speed signals from speed sensor,
EHCU activates solenoid valves incorporated into
the control unit to increase, maintain or decrease
brake fluid pressure.
Refer to AntiÐlock Brake System in Brakes section.

8D Ð 464 WIRING SYSTEM
A/T Shift Indicator
General Description
The circuit consists of mode switch, A/T shift indica-
tor control unit and A/T shift indicator (meter).
A/T shift indicator control unit controls to illuminate
A/T shift indicator light according to signals from
mode switch.

SUPPLEMENTAL RESTRAINT SYSTEM9J±5
1. Energy Reserve Ð The SDM maintains 24±Volt Loop
Reserve (24VLR) energy supply to provide
deployment energy when ignition voltage is lost in a
frontal crash.
2. Frontal Crash Detection Ð The SDM monitors
vehicle velocity changes to detect frontal crashes
which are severe enough to warrant deployment.
3. Air Bag Deployment Ð When a frontal crash of
sufficient force is detected, the SDM will cause
enough current to flow through the air bag assembly
to deploy the air bag.
4. Malfunction Detection Ð The SDM performs
diagnostic monitoring of SRS electrical components
and sets a diagnostic trouble code when a
malfunction is detected.
5. Frontal Crash Recording Ð The SDM records
information regarding SRS status during frontal
crash.
6. Malfunction Diagnosis Ð The SDM displays SRS
diagnostic trouble codes and system status
information through the use of a scan tool.
7. Driver Notification Ð The SDM warns the vehicle
driver of SRS malfunctions by controlling the ªAir
Bagº warning lamp.
The SDM is connected to the SRS wiring harness by a
24±pin connector. This harness connector uses a
shorting clip across certain terminals in the contact area.
This shorting clip connects the ªAIR BAGº warning lamp
to ground when the SDM harness connector is
disconnected or CPA (Connector Position Assurance) is
not inserted even if completely connected. This will
cause the ªAIR BAGº warning lamp to come ªONº steady
whenever the ignition switch is at the ON or START
positions with the SDM disconnected.
827RW044
Legend
(1) SDM
(2) SRS Harness
(3) Connector Position Assurance
ªAir Bagº Warning Lamp
Ignition voltage is applied to the ªAIR BAGº warning lamp
when the ignition switch is at the ON or START positions.
The SDM controls the lamp by providing ground with a
lamp driver. The ªAIR BAGº warning lamp is used in the
SRS to do the following:
1. Verify lamp and SDM operation by turn on 3.5
seconds and then turns ªOFFº when the ignition
switch is first turned ªONº.
2. Warn the vehicle driver of SRS electrical system
malfunctions which could potentially affect the
operation of the SRS. These malfunctions could
result in nondeployment in case of a frontal crash or
deployment for conditions less severe than intended.
The ªAIR BAG º warning lamp is the key to driver
notification of SRS malfunctions. For proper lamp
operation, refer to the ªSRS Diagnostic System Checkº in
this section.
821RW037
SRS Coil Assembly
The SRS coil assembly consists of two current carrying
coils. This is attached to the steering column and allow
rotation of the steering wheel while maintaining
continuous contact of the driver deployment loop to the
driver air bag assembly.
There is a shorting clip on the yellow 2±pin connector near
the base of steering column which connects the SRS coil
to the SRS wiring harness.
The shorting clip shorts to the SRS coil and driver air bag
assembly when the yellow 2±pin connector is
disconnected. The circuit to the driver air bag assembly is
shorted in this way to help prevent unwanted deployment
of the air bag when servicing the steering column or other
SRS components.