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
inflator module high circuit and the inflator module low circuit voltage difference.
By monitoring the voltage difference, the SDM is able to calculate the loop resistance,
High resistance indicates an opern somewhere in the deployment loop.
Conditions for Setting the DTC
DTC B0029 can be set when the loop resistance is high. The following conditions
must be met to set this DTC:
| • | Ignition voltage is present at the SDM and continuous. |
| • | The deployment loop resistance is over 4.8 ohms or circuit 2135
under 2.4 volts with the deployment loop resistance over 6 ohms. |
| • | The 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 loop fault, use the scan tool
to monitor current DTCs. Wiggle the wires and check 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 components for visible damage. |
| • | An open in circuits 2135 or 2136 to the inflator module could cause
this DTC. |
B0029
