My 2003 chevy 3500 will not start. It was perfectly fine earlier today then I noticed my terminals were starting to corrode, so I cleaned them, them after that I got in and fired right up... for about 5 seconds then it turned off, now it will not start. It will crank and then if you hold the key for more than 5 seconds it will stop cranking by itself please help

 

double check your connections. Also look at your grounds. it would be very easy to pull a ground wire lose and cause this issue.

 

Thanks for the info, I found that my plug in cord had a short in it , i fixed it and it runs perfect once again!!