Looking for a movie from the 80s or 90s with a minigun in a van

Hi there, 

as a teenager I watched a movie, but I don't remember the title or what it was about. It contained action and comedy and ist must be from the 80s or 90s. There's only one scene I recall more or less clearly. At one point there is a minigun (like in Predator or Terminator 2) mounted in the cargo space of a van or small delivery truck. There are several car batteries on the floor of that cargo space wired together to power the minigun. Then the gun is fired with only very little control, destroying pretty much everything around that van. I think a pole transformator is among the things that were destroyed, but I'm not so sure about that. Anyway, after the gun has been fired for several seconds, the protagonists look out of the van asking themselves whether they have hit anything or not. Well, that's pretty much it...  Any suggestions?

Cheers,

Marian