DTC 18

Diagnostic Chart:

Notice: When DTC 18 has been set it is necessary to replace the inflatable restraint control module. Setting DTC 18 will also cause DTC 71 to set. When a scan tool clear codes command is issued and the malfunction is no longer present, DTC 18 and DTC 71 will remain current. Make sure that the short to ground condition is repaired prior to installing a replacement inflatable restraint control module to avoid damaging the inflatable restraint control module.

CIRCUIT DESCRIPTION
When you first turn the ignition switch to the RUN position, the inflatable restraint control module performs tests to diagnose critical malfunctions within itself. Upon passing these tests IGNITION 1, 23 VLR and deployment loop voltages are measured to make sure they are within their respective normal voltage ranges. The inflatable restraint control module monitors the voltages at DRIVER SIDE LOW terminal 3 and PASSENGER SIDE LOW terminal 4 to detect shorts to ground in the inflator module circuits. The service wait time is 10 minutes. Refer to enable/disable procedures.

CONDITIONS FOR SETTING THE DTC
^ The driver deployment loop is not open.
^ The passenger deployment loop is not open.
^ The driver deployment is not shorted to voltage.
^ The voltage at DRIVER SIDE LOW terminal 3 is more than 3.3 volts.
^ The voltage at PASSENGER SIDE LOW terminal 4 is less than 3.3 volts for 500 milliseconds.

The following tests check for this DTC. These tests occur when IGNITION 1 is within the normal operating voltage range.
^ POWER-ON-When the malfunction is detected in this test, the RESISTANCE MEASUREMENT test will not be performed.
^ CONTINUOUS MONITORING

ACTION TAKEN WHEN THE DTC SETS
^ The inflatable restraint control module sets DTC 18 and also DTC 71.
^ The inflatable restraint control module turns ON the AIR SAG warning lamp.

CONDITIONS FOR CLEARING THE DTC
DTC 18 is a latched code. You cannot clear a latched code. Repair the malfunction that set this DTC before you replace the inflatable restraint control module.

DIAGNOSTIC AIDS
A short-to-ground in the inflatable restraint I/P module circuit can cause an intermittent condition. Moving wires while monitoring PASS. SENSELO may help locate the fault. A DTC 18 would be accompanied by DTC 71. Inspect CKTs 1403 and 1404 carefully for cutting or chafing. Wiring pigtail damage requires replacement of the inflatable restraint I/P module. A careful inspection of the circuits and components indicated on the DTC 18 Table is essential In order to prevent damage to the replacement Inflatable restraint control module.

DTC TABLE TEST DESCRIPTION
Number(s) below refer to step number(s) on the diagnostic table.
2. This test determines the passenger side low voltage measured by the inflatable restraint control module.
3. This test isolates the malfunction to one side of the inflatable restraint I/P module yellow 2-way connector located behind the passenger knee bolster.
5. This test determines whether the malfunction is in CKT 1403.
7. This test determines whether the malfunction is in CKT 1404.