Supplemental Inflatable Restraint (SIR)

Code 42:

DERM Circuit Detail:

DESCRIPTION:

The DERM measures the deployment loop energy reserve voltage (36VLR) and checks that it remains above 28.4 volts at all times after the initial charging of the reserve is completed (see Code 41). Code 42 indicates an internal fault in the DERM or a resistive short to ground in the 36VLR circuit to the Arming Sensor.

TEST CONDITION:

Tested every 100 milliseconds during "Continuous Monitoring".

FAILURE CONDITIONS:

Code 42 will set if the deployment loop energy reserve voltage (36VLR) is less than 28.4 volts for 500 milliseconds.

CONDITIONS TO CLEAR:

Code 42 will clear if the deployment energy reserve voltage (36VLR) is greater than 28.4 volts for 500 milliseconds after Code 42 has set.

ACTION TAKEN:

DERM turns on the "INFLATABLE RESTRAINT" indicator lamp.

NOTES ON FAULT TREE:

1. Checks for a resistive short to ground in the 36VLR circuit between the DERM and the Dual Sensor.

2. Checks for a short to system voltage on 36VLR circuit.

3. Checks for a resistive short to ground within the Dual Sensor.

4. Checks for shorted diode on dual sensor, If the resistance valve of the 3.48k ohm resistor can be read on a meter, this indicates a shorted diode.