Supplemental Inflatable Restraint (SIR)

CIRCUIT DESCRIPTION
During the first portion of the "Steering Column Resistance Test" the DERM grounds the "Force Low" output, terminal "A10," and monitors the voltage at the "Sense Low" input, terminal "A6." If the voltage at the "Sense Low" input is within a specific range of "Ignition 1" DTC 25 will set. DTC 25 is an indication of a short to B+ on the steering column or in CKTs 347, 348, or 349. Additionally, this diagnostic trouble code can be set if the resistance of the 100 ohm resistor in the resistor module is too high.

TEST CONDITIONS
Test once each ignition cycle during the "Steering Column Resistance Test" if: 1) No malfunctions are detected during "Turn-ON"; 2) No malfunctions are detected during "Continuous Monitoring" for 1 second; 3) No crank signal present; 4) "Ignition 1" voltage is present.

FAILURE CONDITIONS
DTC 25 will set if the voltage at the "Sense Low" input, terminal "A6," is within a specific range of "Ignition 1" voltage during the first portion of the "Steering Column Resistance Test."

ACTION TAKEN
DERM turns "ON" the "INFL REST" warning lamp.

CONDITIONS TO CLEAR
DTC 25 will be cleared each time the ignition switch is turned "OFF."

TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This test removes the steering column from the system. If DTC 25 is still current the problem is not in the steering column.
2. This test checks for a short to B+ in CKT 347.
3. This test checks for a short to B+ in CKT 348 or CKT 349.
4. This test checks for a short to B+ in the "Force Low" circuit.
5. This test checks for proper resistance of the "Force Low" resistor in the resistor module.
6. Since the steering column is setting this diagnostic trouble code it is necessary to replace the inflator module or the SIR coil. It is important to repair the condition in the steering column which caused the damage to the component or wires to avoid damage to the new component.