Circuit Description
When the ignition switch is turned on and during vehicle operation, the SDM
performs tests to detect system faults. One test the SDM performs is to monitor the
passenger deployment loop high circuit and passenger deployment loop low circuit
voltage difference. By monitoring voltage, the SDM is able to detect when the loop
voltage is not between 2.4 and 6.0 volts.
Conditions for Setting the DTC
DTC B0018 can be set when the passenger loop voltage is out of range. The following
conditions must be met to set this DTC.
| • | Ignition voltage is present at the SDM and continuous. |
| • | The passenger deployment loop voltage is over 6 volts or under
2.4 volts with deployment loop resistance under 6 ohms. |
| • | Fault is present for half a second. |
Action Taken When the DTC Sets
| • | The air bag telltale will be on. |
Diagnostic Aids
| • | When attempting to diagnose an intermittent passenger loop fault, use
the scan tool to monitor the current DTCs. |
| | Wiggle the wires and check the connections while watching for a current DTC
to appear and/or disappear on the scan tool. |
| • | Always start diagnosis of the SIR DTCs with an inspection of the wiring
and the components for visible damage. |
| • | A short to ground in circuits 1403 or 1404 could cause this DTC. |
| • | A short between circuits 1403 or 1404 and another vehicle circuit could
cause this DTC. |
B0018
