Just a thought, on the Isuzu Rodeo I had, it would not run without at battery hooked up. even if it was a dead one, it would run with it, but not without it. I messed around with it for a while tryin to figure out a problem with the elec. in the end found out the alt was fried. talked with a guy at a garage and he also said he had that problem with them. said it was just the way they were set up.