Hi;
first I have to say sorry for my bad english,
but I`ll try my best. ;-)

I`ve a Tahoe with a problem wich can`t be fixed in my garage.
Sometimes after a ride I when I stop the engine ther is no more elektical power.
Absolutely nothing works. No radio, light etc..
After a while suddenly ther is power and everything is working as usual.

Is there anyone who knows that problem?

best regards

 

Check the battery cables and then the battery.

 

allready done, OK!
Could it be the A/C RELAY in the Fuse Box ?

 

Never heard of the A/C relay causing that type of problem.
My next stab would be a bad ignition switch.

 

If it would be the ingition switch at least the interrior lights should work.
There is absolut no power in the whole car.

 

Not always, have seen faulty ignition switches kill everything.
But I'll still bet that a replacement battery solves this problem.