I have found it much more reliable to check the outside exhaust for heat than
to try and see if the led comes on.  Pump and hold the buttton for a minute.
Then go check the vent. More than likely the fridge is working. Then wait for
dark to see if the led is bright. Also driving around the block is a lot
better than pumping the dang thing and almost always guarantees a light on
the first time.

disclaimer: this is how it works on my van YMMV ect..

Anyone else notice this?

cheers,
Mark