Chart D SDM Cannot Communicate With Scan Tool

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION
When the ignition switch is first turned On "Ignition 1" voltage is applied to the AIR BAG telltale lamp which is connected to the "AIR BAG" terminal A7 of the SDM. The AIR BAG fuse applies system voltage to the "Ignition 1" input terminal A10 of the SDM. The SDM responds by flashing the AIR BAG telltale lamp seven times by providing a ground. If "Ignition 1" is outside of normal operating voltage range (approximately nine VDC to 16 VDC), the AIR BAG telltale lamp will come On solid with no diagnostic trouble codes set.

CHART TEST DESCRIPTION
The numbers below refer to the step numbers listed on the diagnostic chart.

Step 1. This step checks to make sure the Scan tool is properly connected to the Data Link Connector (DLC).
Step 2. This step verifies the proper software package.
Step 4. This step checks for a short to ground on the "Serial Data" circuit.
Step 7. This step checks for an open in the "Serial Data" circuit.
Step 8. This step checks for a short to the battery. on the "Serial Data" circuit.

When measurements are requested in this chart, use SA 91114NE DVM with correct terminal adapter from SA 9206Z. When a check for proper connection is requested, refer to "Intermittents and Poor Connections." Intermittent Problems
When a wire connector or terminal repair is requested, use the proper repair parts and refer to "Wiring Repair."

NOTICE: Perform "SIR DIAGNOSTIC SYSTEM CHECK" before proceeding with this chart. SIR Diagnostic System Check