Trailer lights and Chevy S-10

[Carl]

Last night I hooked up a hitch to a Chevy S-10 pu which went suprisingly well. I then connected the trailer lights to the truck's wiring. It did not have a harness on the truck, so we connected the appropriate wires. The lights work fine, but now the truck doesn't start. We disconnected the harness wire by wire to trouble shoot, and the problem is the ground wire. With the ground wire disconnected, the truck starts and runs fine, reconnect the ground wire, and it doesn't start. It just cranks and cranks, but never starts. Also check engine light comes on. Anybody else have similar issues or might know the fix to this?


Thanks