Supplemental Inflatable Restraint (SIR)

Code 41 and/or 42:

SIR Wiring Diagram:

DESCRIPTION:

The DERM measures the deployment loop energy reserve voltage 36VLR and checks that it has reached 28.4 volts within 7 seconds after "Ignition 1" is applied. If 28.4 volts is not reached, Code 41 is set. The DERM monitors the 36VLR and checks that it remains above 28.4 volts while "Ignition 1" voltage is present. If the 36VLR falls below 28.4 volts after initial charging Code 42 is set. These codes indicate a fault internal to the DERM or a short to ground between Diode B and the 36VLR output terminal A2.

TEST CONDITIONS:

Code 41 is tested for once each ignition cycle at "Turn-ON". Code 42 is tested every 100 milliseconds during "Continuous Monitoring".

FAILURE CONDITIONS

Code 41 will set if the 36VLR has not reached 28.4 volts 7 seconds after "Turn-ON". Code 42 will set if the 36VLR is below 28.4 volts after initial charging.

ACTION TAKEN:

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

CONDITIONS TO CLEAR:

Code 41 will clear each time the ignition switch is turned "OFF". Code 42 will clear if the 36VLR is above 28.4 volts after initial charging.

TEST DESCRIPTION: Number(s) below refer to circled number(s) on the diagnostic chart.

1. This test determines whether Diode A is shorted. If DVM shows a value out of its readable limits (i.e. "OL" or infinite resistance), diode A is assumed good. This assumption is made because a diode approximates an infinite resistance unless biased to pass current. Any readable resistance value indicates a shorted diode A and thus a faulty dual sensor.

2. This test checks for a short from the 36VLR circuit to B+.