Searched the Renntech forum on this and didn't find anything other than lubricating the latch mechanism so that the light switch (
microswitch) works properly.
The switch must be working if the red and yellow wires read 12 volts; interestingly, if I use the cars ground instead of the yellow wire, the light will work.
And, the yellow wire showed continuity with the cars ground....
The Renntech forum indicated both front and rear come on together---don't know if this is true, but if it is true, could there be somthing else going on ? I'll revist this again today....