When you first turn ON the ignition, the inflatable restraint sensing and diagnostic module (SDM) performs tests to diagnose critical malfunctions within itself. Next the SDM measures IGNITION 1 and the deployment loop voltages to make sure they are within their respective normal voltage ranges. Then the SDM proceeds with the resistance measurement test. During one portion of the resistance measurement test, the SDM does the following:
• | Grounds the passenger side low circuit through an internal circuit sink. |
• | Connects the passenger side high circuit to an internal constant current source. This current produces proportional voltage drops in the deployment loop. |
• | Measures the voltage difference between the passenger side high circuit and the passenger side low circuit. |
• | Calculates the resistance of the passenger deployment loop using the measured voltage. |
• | The driver and passenger deployment loops are not open. |
• | The driver and passenger deployment loops are not shorted to voltage. |
• | The passenger deployment loop is not shorted to ground. |
The passenger deployment loop resistance is less than 1.4 ohms.
The resistance measurement test checks for this malfunction. This test occurs once each ignition cycle when IGNITION 1 is within the normal operating voltage range.
The SDM commands ON the AIR BAG warning lamp.
• | The passenger deployment loop resistance is less than 1.4 ohms. |
• | You can issue a CLEAR CODES command. |
• | A history DTC will clear once 255 malfunction free ignition cycles have occurred. |
The following can cause an intermittent condition:
• | A short between the passenger side high circuit and the driver side high circuit. |
• | A short between the passenger side high circuit and the driver side low circuit. |
• | A short between the passenger side high circuit and the passenger side low circuit. |
• | A malfunctioning shorting bar on the inflatable restraint IP module connector. |
The diagnostic table directs the technician to note the entry value of PASSENGER RESISTANCE. Comparing the value of PASSENGER RESISTANCE over multiple ignition cycles 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.
The numbers below refer to the step numbers on the diagnostic table:
This step checks the passenger deployment loop resistance that was measured by the inflatable restraint sensing and diagnostic module (SDM).
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 between the passenger side high circuit and the passenger side low circuit.
This step checks to see if there is a short between the passenger side high circuit and the driver side low circuit.
Step | Action | Value(s) | Yes | No |
---|---|---|---|---|
1 | Did you perform the SIR Diagnostic System Check? | -- | ||
Is DTC B1022 also present? | -- | |||
3 |
Did you complete the repair? | -- | -- | |
4 |
Is PASSENGER RESISTANCE less than the specified value? | 1.4 ohms | ||
5 |
Did you complete the repair? | -- | -- | |
Is PASSENGER RESISTANCE less than the specified value? | 1.4 ohms | |||
7 |
Did you complete the repair? | -- | -- | |
Is the measured resistance less than the specified value? | OL | |||
9 | Locate a short between the passenger side high circuit and the passenger side low circuit. Did you complete the repair? | -- | -- | |
Use the J 39200 to measure the resistance between the passenger side high circuit and the driver side low circuit of the SDM wiring harness connector. Is the measured resistance less than the specified value? | OL | |||
11 | Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement . Did you complete the repair? | -- | -- | |
12 |
Did you complete the repair? | -- | -- | |
13 |
Did you complete the action? | -- | -- |