To test engine components:
Don't use this if you don't know what you are doing!!
1. Be sure ignition is turned off.
2. Close the switch
3. Turn on ignition
4. Within 1-12 seconds open the switch again
5. Wait some seconds
6. First code 91 will appear. Meaning the fuel pump will be activated periodically.
7. Close the switch for 3-5 seconds to test the next component.
8. Repeat until you arrived at the component which you want to test.
To tune the engine ecu:
Don't use this if you don't know what you are doing!! (I never tried it, so I don't guarantee it will work. It should work however on a Fenix 3B ecu (3.0 V6-12)
1. Be sure ignition is turned off.
2. Close the switch
3. Turn on ignition
4. Within 1-12 seconds open the switch again
5. Within 3 seconds close the switch again for 3-5 seconds.
6. Open the switch for 3 seconds (5 max)
7. Close the switch again for 3-5 seconds.
8. Open the switch again.
9. The ECU should indicate code 22 by blinking. Meaning program start.
10. Enter code 2 by means of close 5 secs, open 3 secs, close 5 secs, open again.
11. The ECU will return 12 by blinking. Meaning 4 degrees ignition advance.
12. Close switch for 10-20 seconds. ECU will indicate code 11, meaning 2 degrees earlier.
Regretfully I don't have more data on this.

Beschreibung der Codes:

Code Description
**** ECU XM V6 Fenix 3B (activate components)
Component activation is performed 
91 Activate fuel pump relais
92 Activate fuel injectors
93 Activate idling actuator
94 Activate canister discharge valve
95 Activate relais airco compressor
 
**** ECU XM V6 Fenix 3B (Mixture adjustment)
11 Make mixture richer
22 Make mixture leaner
33 Program start
99 upper or lower limit reached
 
**** ECU XM V6 Fenix 3B (Ignition timing adjustment)
11 2 degrees advance
12 4 degrees advance
13 6 degrees advance
14 8 degrees advance
19 default setting
22 Program start
99 upper or lower limit reached