This is how to read a 2004 Peugeot 407 SID803 ecu. Attach the BDM pinouts from the ribbon cable to the ecu and which ribbon cable to use for Ktag.
When you do not have an adapter you need to use a gray 10 pin cable to bdm. Pin it and solder the 5 wires, pin 1 is the one with the red line, then count it to 10 and solder according the picture by 1,5,6,7,8 pin (number one have red line), don’t forget with power supply to the ecu.
In sid 803 / 803A no connection power supply to bdm slot, only to plug, so don’t worry about ecu, it is very hard to damaged it.Matching a new ecu is very easy, just copy the eeprom and in some cases calculate the checksum.
Good luck. For any issues of ECU R/W, please go to http://www.obd2diy.fr/ for help.