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 proceeds to continuous monitoring. The SDM contains a resistor network connected to 5 volts, ground, and to the SDM front end sensor feed. The 1.0 K ohms resistor in the inflatable restraint front end discriminating sensor parallel to the normally open switch provides a parallel path to ground. This causes a specified percentage of voltage in order to appear at the SDM front end sensor feed input. The SDM monitors this voltage to detect a short to power or an open discriminating sensor.
Conditions for Running the DTC
| • | The SDM is configured for an inflatable restraint front end discriminating sensor. |
| • | Ignition 1 voltage is within the normal operating voltage range. |
| • | Front end discriminating sensor input circuit is not shorted to voltage. |
Conditions for Setting the DTC
The voltage at front end discriminating sensor input terminal is more than 3.4 volts for 500 milliseconds.
Action Taken When the DTC Sets
The SDM commands ON the AIR BAG warning lamp via Class 2 serial data.
Conditions for Clearing the DTC
| • | The voltage at front end sensor input terminal is less than or equal to 3.4 volts for 500 milliseconds. |
| • | You can issue a CLEAR CODES command |
| • | A history DTC will clear once 250 malfunction free ignition cycles have occurred |
Diagnostic Aids
The following can cause an intermittent condition:
| • | A short to voltage in the inflatable restraint front end discriminating sensor input circuit. |
| • | Cutting or chafing of front end discriminating sensor input and/or ground circuit. |
If any of the above conditions are found refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
Test Description
The numbers below refer to the step numbers on the diagnostic table:
-
This test checks for proper contact or corrosion of the yellow 2-way connector.
-
This test checks for an open or high resistance discriminating sensor input circuit.
-
This step is the replacement of SDM.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check? | -- | ||||||||
Does connector exhibits any signs of corrosion, terminal damaged, or poor connections? | -- | |||||||||
3 | Replace the wiring harness side of in-line connector. Refer to Connector Repairs in Wiring Systems. Did you complete the replacement? | -- | -- | |||||||
4 | Inspect the front end sensor for the following conditions:
Does front end sensor exhibits any signs of corrosion, terminal damaged, or poor connections? | -- | ||||||||
5 | Replace the inflatable restraint front end discriminating sensor. Refer to Inflatable Restraint Front End Discriminating Sensor Replacement . Did you complete the replacement? | -- | -- | |||||||
6 | Use the J 39200 DMM and measure the resistance between the front end sensor connector sensor input and sensor ground circuits. Does the resistance measure greater than the specified value? | 1050 ohms | ||||||||
Use the J 39200 and measure the resistance between the front end sensor connector sensor sensor ground circuit and a known good ground. Does the resistance measure greater than the specified range? | 0.0-5.0 ohms | |||||||||
8 | Locate and repair the short and/or high resistance in front end sensor ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |||||||
9 |
Is the connector damaged or corroded? | -- | ||||||||
10 | Repair or replace the SDM wiring harness connector. Refer to Connector Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |||||||
11 | Use the J 39200 and measure the resistance of the front end sensor input circuit between the front end sensor connector and SDM connector. Does the resistance measure greater than the specified range? | 0.0-5.0 ohms | ||||||||
12 | Locate and repair the open or high resistance in front end sensor input circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |||||||
13 |
Does the voltage measure less than the specified value? | 1.0 V | ||||||||
14 |
Have the repairs been completed? | -- | -- | |||||||
Replace the inflatable restraint sensing and diagnostic module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement . Did you complete the replacement? | -- | -- | ||||||||
16 |
Did you complete the action? | -- | -- |
