Isuzu 2000 Trooper Workshop Manual page 2124

DTC 21 Driver Deployment Loop Resistance High
Circuit Description:
When the ignition switch is turned "ON", the SDM will
perform tests to diagnose critical malfunctions within
itself. Upon passing these tests, "Ignition 1",
deployment loop voltages are measured to ensure they
are within their respective normal voltage ranges.
The SDM then proceeds with the "Resistance
Measurement Test" "Driver Bag Low" terminal "4" is
grounded through a current sink and the driver current
source connected to "Driver Bag High" terminal "3" allows
a known amount of current to flow. By monitoring the
voltage difference between "Driver Bag High" and "Driver
Bag Low", the SDM calculates the combined resistance
of the driver air bag assembly, SRS coil assembly,
harness wiring CKTs IB05–YEL and IB06–YEL/BLK, and
connector terminal contact.
DTC Will Set When:
The combined resistance of the driver air bag assembly,
SRS Coil assembly, harness wiring CKTs IB05–YEL and
IB06–YEL/BLK, and connector terminal contact is above
a specified value. This test run once each ignition cycle
during the "Resistance Measurement Test" when:
1. No "higher priority faults" are detected during
"Turn–ON"
2. "Ignition 1" voltage is in the specified value.
RESTRAINT CONTROL SYSTEM
Action Taken:
SDM turns "ON" the "AIR BAG" warning lamp and sets
DTC 21.
and
DTC Will Clear When:
The ignition switch is turned "OFF".
DTC Chart Test Description:
Number(s) below refer to step number(s) on the
diagnostic chart:
2. This test determines whether the malfunction is in
the SDM.
3. This test verifies proper connection of the yellow
2–pin connector at the base of the steering column.
4. This test checks for proper contact and/or corrosion
of the 2–pin connector terminals at the base of
steering column.
5. This test isolate the malfunction to one side of the
SRS coil assembly yellow 2–pin connector located
at the base of the steering column.
6. This test determines whether the malfunction is due
to high resistance in the wiring.
7. This test determines whether the malfunction is in
the SRS coil assembly or the driver air bag
assembly.
9J1–23
D09RW001