OK, found it.
I was going to open my EVSE that came with the car and my LCS-20, both made by Clipper Creek, and list the differences.
There indeed was enough information to do that without voiding two EVSE warranties.
Here's what I found (posted on another thread too):
Here's where I think the differences are between the LCS-20 (L2 EVSE) and the GM supplied EVSE made also by Clipper Creek:
1) The relay (T92P7A24-XXX part number) coil runs off of the input voltage. XXX is the coil voltage - 120 and 240 (among others) are available. If it's an L1 EVSE, then they use a version of the relay that uses a 120V coil. If it's an L2 EVSE, they use a version of the relay that runs off of 240V. This is what makes the "Chris TX" mod (
http://gm-volt.com/forum/showthread...-how-to-modify-Voltec-L1-EVSE-to-do-L1-and-L2) so clever - it uses 120V for ALL the circuitry and just switches 240V instead of 120V. Clever. But, it requires a neutral line in addition to the 240V lines - I believe that a 240V Clipper Creek unit doesn't use the neutral line (it measures open with my meter).
2) JMP4 is a set of jumpers used to select the primary voltage for the small (2.5 Watt, VPP36-070 for the part number) for the control power. If the two outer jumpers are installed, the transformer primaries are in parallel (120V). If the center jumper is installed, the transformer primaries are in series (240V).
3) JMP1-JMP3 are to tell the microprocessor what particular model (and current capabilities) the unit is. I don't have the magic decoder ring for this one.
4) I suspect, but can't say for sure, that the gauge of the charging cord is changed between a 3.3 kW unit and a 6.6 kW unit.
So, by jumper settings, different power relay input coils & different output cords, Clipper Creek can use the same board for many of (all of?) their products. Very slick!
Thanks all for indulging me.