DTC 21

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", and 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.

Action Taken
SDM turns "ON" the "AIR BAG" warning lamp and sets DTC 21.

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.

Diagnostic Aids:
An intermittent condition is likely to be caused by a poor connection at
terminals "1" and "2" of the SRS coil 2-pin connector at the base of the
steering column, terminal "1" and "2" of the driver air bag assembly 2-pin connector at the top of the steering column, SDM terminals "3" and "4" or a poor wire to terminal connection in CKT IB05-YEL or IB06-YEL/BLK. The test for this diagnostic trouble code is only run while the "AIR BAG" warning lamp is performing the bulb check, unless DTC 17 or DTC 26 is detected. When a scan tool "Clear Codes" command is issued and the malfunction is still present, the DTC will not reappear until the next ignition cycle.