When you first plug the module into the OBD2 port, you may see the LED cycle in a pattern (units produced after Sept. 22rd 2014) which is just an indication that it is performing internal hardware diagnostic checks before going into full operating mode. Earlier modules may not cycle the LEDs (but still perform the hardware checks in "silent" mode).
During operation, it is normal to see the lights cycle and go on/off in different sequences sometimes appearing to dim or vary in brightness (or even almost go dark). The lights are not really useful to you as the driver, but are used more for diagnostic or status indications when doing troubleshooting/verification. You will see the lights dim dramatically as you slow down/brake. As long as the vehicle is staying in V8 the unit is operating normally.
Also, the units have a "SLEEP" mode where after you shut the key off and/or the engine is not running. All the LIGHTS WILL GO OUT and it will go into power saving mode.
This power saving mode is EXTREMELY low powered and on a normal capacity battery in normal temperatures (i.e. ~70 degrees F) it should not affect normal battery voltage/charge for at least a couple of weeks (and probably much longer). The maximum draw in sleep mode is 6mA (and is nominally about 2-3mA).
The device will wake up again when you start the engine and the LEDs may cycle 2-3 times as the unit performs internal diagnostics. Earlier versions may not cycle the LEDs.
It may take up to 20 seconds (usually less) for it to start showing lights again ... this is NORMAL because it may take that long before we can send commands to the vehicle (especially on a cold motor).
