Chart G DERM Cannot Communicate With Scan Tool

Diagnosis Chart:

Electrical Chart:

DESCRIPTION
When the Ignition Switch is first turned "ON" system voltage is applied through Fuse #6 to the "SIR Indicator High" input (B9) and the "INFLATABLE RESTRAINT" warning lamp which is connected to "SIR Indicator Low" input (A1). Fuse #7 also applies system voltage to the "IGNITION 1" inputs (A3 and B3). The DERM responds by blinking the "INFLATABLE RESTRAINT" warning lamp 7 to 9 times.

When the engine is being cranked, system voltage is applied to the DERM at the "CRANK" input. The DERM grounds the warning lamp circuit until system voltage is removed from the "CRANK" input. This results in a steady "INFLATABLE RESTRAINT" warning lamp during cranking.

After cranking the DERM again blinks the "INFLATABLE RESTRAINT" warning lamp 7 to 9 times.

NOTES ON FAULT TREE
1. An improper connection to the data link connector (DLC) prevents communications from being established.
2. The correct "Body Systems" cartridge must be used.
3. This checks the "Serial Data" circuit for proper voltage. An open, short to ground or short to voltage in any wire or component attached to this circuit causes scan tool communications to fail.
4. This test checks for a short to ground on the "Serial Data" circuit between the DERM and the DLC connector.
5. This test checks for an open in the "Serial Data" circuit between the DERM and the DLC connector.
6. This test checks for a short to voltage on the "Serial Data circuit between the DERM and the DLC connector.
7. This test checks for poor terminal connections in the "Serial Data" circuit between the DERM and the DLC connector.