not starting

Went to start my truck and would not turn over. I just got home a half an hour before and truck was running fine. When testing the battery it said 12.6 and when I would hit my unlock button on my key chain the amps would shoot to 0.
I changed out to a new battery and will crank, but will not turn over. When I try to read the computer it says it is not getting communication. could the ecu be bad and how to test?

 

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Someone better with electrical help than me will be along shortly.

 

My initial response to your issue would be to check the that your connections are tight on the battery terminals. You changed batteries, so I imagine this isn't the issue, but worth rechecking that they're clean and have good contact. Checking the main ground wire off the battery is next.

Do you have any aftermarket components? Checking those and the associated grounds would be next. There have been people who fried their ECU by trying to jump the vehicle improperly, but you don't mention jumping it.

That's about all I'm good for.

 

I did try to give a guy a jump and he had the cables on the wrong terminal on there car that was dead, but that was a couple weeks ago and have driven since then. Would that have fried my ECU and would it have waited so long to short my battery and die.

I do have after market headlights, but they have been on over a year.

Thanks for all help you know more than me.

 

Did you check your fuses?