Electrical damage from incorrect connection to battery terminal

[madeEASY]

I have a problem, if you have any ideas, please help

I own 1999 GMC Sierra
one evening my battery died by the restaraunt and my friend brought another battery to start my pickup truck. he installed the battery and because it was dark he didn't see that he hooked up new battery incorrectly, plus to minus and minus to plus. I started the car, and of course it didn't start but some smoke came up from the wire coming from the battery. I switched the better around, hooked it up correctly and started the car. the car worked without problem probably for a week.

right now it doesn't start, i took it to a dealer, he changed few things that he thought would be a problem. the funny thing is that the truck would work for a day or two after being serviced and then dies again.

it did that couple times, after it had a new part put in, it would work for a day or two, and then dies. right now its sitting home. the thing is that the engine turns but it doesn't start. Recently i remembered about that evening when my friend incorrectly hooked up the battery so i'm thinking thats what probably caused my recent problems. i'm thinking that maybe that something electrical is damaged, fuses look ok. is it possible that computer is damaged? would a computer change would solve this problem? or is there some sort of a safety device that maybe thats damaged?

Ben

[horse482]

I have seen this before and it has fried the ecm.