Chevrolet Repair: Starting problem comes and goes., jumper cables, starter solenoid

Question
I have a 97 blazer 4x4.  It has starting problems that come and go.  When it will not start I turn the key and nothing happens.  No clicking, cranking, nothing at all.  All of the lights are working, radio and other electrical components.  If I get someone to hook up jumper cables it STARTS right up.  This problem comes and goes.  I was starting to think it was a bad cable.  A care repair center tested the electrical system said something like it says it is discharging but it is not. A lady there had a truck just like it and said that it MIGHT be the (panel) GUAGE controler (or something) that is in the dashboard.  I thought if the battery is going dead that it would at least try to crank a little and the lights would be dimmer or not working either.  They told me to take it to the dealer.  
They did not seem 100% positive that that was the problem.  

Answer
Sounds like a loose or dirty connection. The jumper cables just supply enough more power to overcome the resistance of the bad connection.

It could be the connector through the firewall, the ignition switch or its connector, the connection at the starter, or the starter solenoid internal connections.
Just need to make sure they are all clean and tight.
There should be a ground wire from the engine to yhe firewall also.
Make sure it is there, and clean and tight.

Van