Component Description; Srs Component And Wiring Location View; Sdm (Sensing And Diagnostic Module) - Isuzu 1999 RODEO Workshop Manual

9J–4
SUPPLEMENTAL RESTRAINT SYSTEM
SRS Component and Wiring Location
View
Legend
(1) Battery
(2) Relay & Fuse Box
(3) Passenger Air Bag Assembly
(4) SDM
(5) Meter Assembly
(6) SRS Coil Assembly
(7) Driver Air Bag Assembly
(8) Starter Switch
(9) Fuse Box, SRS–1

Component Description

SDM (Sensing and Diagnostic Module)

WARNING: DURING SERVICE PROCEDURES, BE
VERY CAREFUL WHEN HANDLING A SENSING AND
DIAGNOSTIC MODULE (SDM). NEVER STRIKE OR
JAR THE SDM. NEVER POWER UP THE SRS WHEN
THE SDM IS NOT RIGIDLY ATTACHED TO THE
VEHICLE. ALL SDM AND MOUNTING BRACKET
FASTENERS MUST BE CAREFULLY TORQUED AND
THE ARROW MUST BE POINTED TOWARD THE
FRONT OF THE VEHICLE TO ENSURE PROPER
OPERATION OF THE SRS. THE SDM COULD BE
ACTIVATED WHEN POWERED WHILE NOT RIGIDLY
ATTACHED TO THE VEHICLE WHICH COULD CAUSE
DEPLOYMENT AND RESULT IN PERSONAL INJURY.
The Sensing and Diagnostic Module (SDM) is designed
to perform the following functions in the SRS:
1. Energy Reserve — The SDM maintains 24–Volt Loop
Reserve (24VLR)
deployment energy when ignition voltage is lost in a
frontal crash.
2. Frontal Crash Detection — The SDM monitors
vehicle velocity changes to detect frontal crashes
which are severe enough to warrant deployment.
3. Air Bag Deployment — 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 — The SDM performs
diagnostic monitoring of SRS electrical components
and sets a diagnostic trouble code when a
malfunction is detected.
5. Frontal Crash Recording — The SDM records
information regarding SRS status during frontal
crash.
6. Malfunction Diagnosis — The SDM displays SRS
diagnostic trouble
information through the use of a scan tool.
7. Driver Notification — The SDM warns the vehicle
driver of SRS malfunctions by controlling the "Air
Bag" warning lamp.
The SDM is connected to the SRS wiring harness by a
24–pin connector.
shorting clip across certain terminals in the contact area.
This shorting clip connects the "AIR BAG" warning lamp
810RW003
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 "AIR BAG" warning lamp to come "ON" steady
whenever the ignition switch is at the ON or START
positions with the SDM disconnected.
energy supply to
codes and system status
This harness connector uses a
provide
827RW023