GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2007 🢒 Epica 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC B1620

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.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B1620 ECU Performance

Conditions for Running the DTC

Ignition voltage is within the normal operating voltage range.

Conditions for Setting the DTC

The SDM does not implement diagnostic operation. In case of the above, the wiring harness of the SDM should be inspected before replacing the SDM.

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

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
  1. Confirm the ignition switch is OFF.
  2. Wait for 1 minute for the sensing and diagnostic module (SDM) charger to be discharged.

Has the SDM discharged?

Go to Step 3

--

3

Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .

Is the replacement complete?

Go to Step 4

--

4
  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