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.

### Reference

When the ignition switch is turned ON, the warning lamp blinks 6 times during 6 seconds.

If the warning lamp stays ON or blinks a second after the above normal blinking, 6 times during 6 seconds, then it is regarded as a defect, old or current. Please inspect the defect with the scan tool.

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 F1. Is the fuse blown? | -- | Go to Step 3 | Go to Step 4
3 | Replace fuse F1. Is the repair complete? | -- | Go to Step 14 | --
4 |

1. Confirm the ignition switch is ON.
2. Measure the voltage from fuse F1.

Is the voltage within the specified range?

9-16 V

Go to Step 6

Go to Step 5

5 | Repair the power supply and the wiring to fuse F1. Is the repair complete? | -- | Go to Step 14 | --
6 |

1. Confirm the ignition switch is ON.
2. Remove the instrument cluster.
3. Measure the voltage from terminal A35 of the cluster wiring connector.

Is the voltage within the specified range?

9-16 V

Go to Step 8

Go to Step 7

7 | Repair the wiring between fuse F1 and terminal A35 of the cluster wiring connector. Is the repair complete? | -- | Go to Step 14 | --
8 | Inspect the connection between terminal A35 and A27 of the cluster. Is the connection OK? | -- | Go to Step 10 | Go to Step 9
9 | Replace the instrument cluster. Refer to Instrument Cluster Replacement . Is the repair complete? | -- | Go to Step 14 | --
10 |

1. Confirm the ignition switch is OFF.
2. Disconnect the connector of the sensing and diagnostic module (SDM).
3. Measure the resistance between terminal A27 of cluster connector and terminal 27 of the SDM connector.

Is the resistance as specified?

0 ohms

Go to Step 11

Go to Step 13

11 | Measure the resistance between terminal 27 of the SDM connector and ground, battery positive. Are the resistances as specified? | ∞ | Go to Step 12 | Go to Step 13
12 | Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement . Is the repair complete? | -- | Go to Step 14 | --
13 | Repair the wiring between terminal 27 of the SDM and the instrument cluster. Is the repair complete? | -- | Go to Step 14 | --
14 |

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