Before you start, use an ohmmeter to ensure you have good solder joints and connectors on the TTL-level asynchronous serial port of the ECU. Ensure there are no solder bridges between any of the CN2 pads. Ensure CN2 Pin 1 has connectivity to any of the ECU harness connector ground pins. I’ll post the pins that CN2 Pins 2 and 4 should have connectivity to later.

Before you start, use an ohmmeter to ensure you have good solder joints and connectors on the TTL-level asynchronous serial port of the ECU. Ensure there are no solder bridges between any of the CN2 pads. Ensure CN2 Pin 1 has connectivity to ground. Ensure CN2 Pin 2 has connectivity to the 66207 processor Pin 42, Rx Data. Ensure CN2 Pin 3 has connectivity to any Vcc pin of any IC, I used Pin 28 of the PROM socket. Ensure CN2 Pin 4 has connectivity to IC19 Pin 6, must be Tx Data. As of 1/2/05, this is backwards from Nicolas Mailloux's document on http://www.ecucontrol.com/seria_ladapter.htm. I will ping him to resolve this.