Supplemental Inflatable Restraint (SIR)

Code 26:

DERM Circuit Detail:

DESCRIPTION:

If there is an open in the SIR Coil, Inflator Module or wiring in the steering column the resistance between the Sense Hi input (terminal A7) and the Sense Low input (terminal A6) increases. This increased resistance causes a larger voltage drop from the Sense Hi input to the Sense Low input, across the 430 ohm resistor in the Resistor Module. The increase in voltage between the Sense Hi input and the Sense Low input is sensed by the DERM during the "Continuous Monitoring" Tests and Code 26 is set.

TEST CONDITION:

Tested every 100 milliseconds during "Continuous Monitoring".

FAILURE CONDITIONS:

Code 26 will set if the voltage at the Sense Hi input (terminal A7) minus the voltage at the Sense Low input (terminal A6) is greater than 0.45 volts for 500 milliseconds.

CONDITIONS TO CLEAR:

Current Code 26 will clear if the voltage at the Sense Hi input (terminal A7) minus the voltage at the Sense Low input (terminal A6) is greater than 0 volts but less than 0.40 volts for 500 milliseconds after Code 26 has been set.

ACTION TAKEN:

DERM turns on the "INFLATABLE RESTRAINT" indicator lamp.

NOTES ON FAULT TREE:

1. Checks if fault is in the Steering Column.

2. Checks if fault is in the Inflator Module or the SIR coil.

3. Checks if fault is in the Resistor Module or in the terminal contacts at the base of the Steering Column.

4. Checks for defective connector at the wiring harness.