STO1 - Check STO Wire to PCM For Open

- Key OFF.

- Install Breakout Box (leave PCM disconnected).

- Measure the resistance between BOB Test Pin STO and data link connector PCM STO wire.

- Is the resistance less than 5 ohms?

Yes -- Go to STO2. STO2 - Check STO Wire to PCM For Short

No -- Service the PCM STO wire to data link connector for opens.