For 1990-2009 cars

### Circuit Description

When the ignition switch is turned to ON, the sensing and diagnostic module (SDM) will perform a turn-on test to diagnose critical malfunctions within the SDM itself.

Upon passing these tests, ignition and deployment loop voltages are measured to ensure that they are within their normal voltage ranges. The SDM monitors the voltages at the driver low and the passenger low to detect shorts to ground or voltage in the deployment loops.

If the warning lamp operates properly ON and OFF, the SDM measures the voltage continuously from the warning lamp terminal.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B2500 Inflatable Restraint System Indicator Circuit

### Conditions for Running the DTC

Ignition voltage is within the normal operating voltage range.

### Conditions for Setting the DTC

The warning lamp does not blink properly ON and OFF.

### Action Taken When the DTC Sets

The SDM commands the AIR BAG indicator ON.

### Conditions for Clearing the DTC

The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
Caution: Refer to Sensing and Diagnostic Module Handling Caution in the Preface section. Caution: Refer to Sensing and Diagnostic Module Voltage after Ignition is Turned Off Caution in the Preface section. Schematic Reference: SIR Schematics Connector End View Reference: SIR Connector End Views
1 | Did you perform a Diagnostic System Check - Vehicle? |  | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 | Inspect fuse F3. Is the fuse blown? | -- | Go to Step 3 | Go to Step 4
3 | Replace fuse F3. Is the repair complete? | -- | Go to Step 15 | --
4 |

1. Confirm the ignition switch is ON.
2. Measure the voltage from fuse F3.

Is the voltage within the specified range?

9-14 V

Go to Step 6

Go to Step 5

5 | Repair the power supply and the wiring to fuse F3. Is the repair complete? | -- | Go to Step 15 | --
6 |

1. Confirm the ignition switch is OFF.
2. Remove the instrument cluster.
3. Inspect the bulb of the air bag warning lamp.

Is the bulb OK?

--

Go to Step 8

Go to Step 7

7 | Replace the bulb of the air bag warning lamp. Is the repair complete? | -- | Go to Step 15 | --
8 |

1. Confirm the ignition switch is ON.
2. Measure the voltage from terminal B15 of the cluster wiring connector.

Is the voltage within the specified range?

9-14 V

Go to Step 10

Go to Step 9

9 | Repair the wiring between fuse F3 and terminal B15 of the cluster wiring connector. Is the repair complete? | -- | Go to Step 15 | --
10 | Inspect the connection between terminal B15 and B13 of the cluster. Is the connection OK? | -- | Go to Step 12 | Go to Step 11
11 | Replace the cluster. Is the repair complete? | -- | Go to Step 15 | --
12 |

1. Confirm the ignition switch is OFF.
2. Disconnect the connector of the I/P module and the connector of steering wheel module coil.
3. Disconnect the connector of the sensing and diagnostic module (SDM).
4. Confirm the ignition switch is ON.
5. Measure the resistance between terminal 27 of the SDM connector and terminal B13 of the cluster connector.

Is the resistance as specified?

0 ohms

Go to Step 13

Go to Step 15

13 | Measure the resistance between terminal 27 of the SDM connector and ground. Is the resistance as specified? | ∞ | Go to Step 14 | Go to Step 15
14 | Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement . Is the repair complete? | -- | Go to Step 16 | --
15 | Repair the wiring between terminal 27 of the SDM and the cluster. Is the repair complete? | -- | Go to Step 16 | --
16 |

1. Reconnect all SIR components.
2. Verify that all components, connectors and connector position assurances (CPAs) are properly mounted.
3. Use the scan tool in order to clear the DTCs.
4. Operate the vehicle within the Conditions for Running the DTC, as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK