Circuit Description
When you first turn ON the ignition, the inflatable restraint sensing and diagnostic module (SDM) performs tests to diagnose critical malfunctions within itself. Then the SDM performs the following continuous diagnostic tests on the deployment loops:
| • | Deployment loop voltage out of range test |
| • | Deployment loop resistance measurement test |
Upon passing these tests IGNITION 1, 23VLR and the deployment loop voltages are measured to make sure they are within their respective normal voltage ranges. The SDM monitors the voltages at the driver side low circuit and the passenger side low circuit to detect shorts to ground in the inflator module circuits.
When the malfunction is detected in this test, the resistance measurement test will not be performed.
Conditions for Running the DTC
| • | Ignition 1 voltage is within the normal operating voltage range. |
| • | The driver and passenger deployment loops are not open. |
| • | The driver deployment loop is not shorted to voltage. |
Conditions for Setting the DTC
| • | The voltage at the driver side low circuit is more than 3.3 volts. |
| • | The voltage at the passenger side low circuit is less than 3.3 volts for 500 milliseconds. |
Action Taken When the DTC Sets
The SDM commands ON the AIR BAG warning lamp.
Conditions for Clearing the DTC
DTC B1018 is a latched code. You cannot clear a latched code. Repair the malfunction that set this DTC before you replace the SDM.
Diagnostic Aids
A short to ground in the inflatable restraint IP module circuit can cause an intermittent condition. A DTC B1018 would be accompanied by DTC B1071. Inspect the passenger side high circuit and the passenger side low circuit carefully for cuting or chafing. Wiring pigtail damage requires replacement of the inflatable restraint IP module. A careful inspection of the circuits and components indicated on this table is essential in order to prevent damage to the replacement inflatable restraint sensing and diagnostic module (SDM). This table directs the technician to note the entry value of PASSENGER SENSELO. Comparing the value of PASSENGER SENSELO can be helpful in determining if an intermittent condition exists.
When measurements are requested in this table, use the J 39200 DMM with the correct terminal adapter from the J 35616 Connector Test Adapter Kit. When an inspection for proper connection is requested, refer to Testing for Electrical Intermittents in Wiring Systems. When a wire, connector or terminal repair is requested, use the J-38125 Terminal Repair Kit and refer to Wiring Repairs in Wiring Systems.
Test Description
The numbers below refer to the step numbers on the diagnostic table:
-
This step checks the passenger side low voltage that was measured by the inflatable restraint sensing and diagnostic module (SDM). A reading of 3.3 V or more indicates that an intermittent condition may exist.
-
This step isolates the malfunction to one side of the inflatable restraint IP module yellow 2-way connector.
-
This step checks to see if there is a short to ground in the passenger side high circuit.
-
This step determines if there is a short to ground in the passenger side low circuit or if there is a malfunctioning SDM.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
|
Notice: When DTC B1018 or B1024 has been set it is necessary to replace the inflatable restraint Sensing and Diagnostic Module (SDM). Setting DTC B1018 or B1024 will also cause DTC B1071 to set. When a scan tool clear codes command is issued and the malfunction is no longer present, DTC B1018 or B1024 and DTC B1071 will remain current. Make sure that the short to ground condition is repaired prior to installing a replacement SDM to avoid damaging the SDM. | ||||
1 | Did you perform the SIR Diagnostic System Check? | -- | ||
Is the PASSENGER SENSELO less than the specified value? | 3.3 V | Go to Diagnostic Aids | ||
Is PASSENGER SENSELO less than the specified value? | 3.3 V | |||
4 |
Did you complete the repair? | -- | -- | |
Is the measured resistance less than the specified value? | OL | |||
6 |
Did you complete the repair? | -- | -- | |
Use the J 39200 to measure the resistance between the passenger side low circuit and the ground circuit of the SDM wiring harness connector. Is the measured resistance less than the specified value? | OL | |||
8 |
Did you complete the repair? | -- | -- | |
9 |
Did you complete the action? | 3.3 V | -- | |
