Anti-theft indicator. Truck won't start.

So I'm installing a 20" light bar in my 2010 5.4L. I unhook the negative battery cable, do my thing, and when I hooked power back up, I get the anti-theft indicator and my truck won't start with either of the original keys I have for it.

I checked all the fuses. All are visually OK. I searched and tried doing the key re-program thing found here, but it didn't work. I tried various other oddball tactics I read online, too:
* Tilt the wheel
* Turn the key to 'On' and leave it in the ignition for 10 minutes
* Unhook the battery and hook it back up after 10 minutes with the key in the ignition

...and so on. Nothing's worked so far. Please don't tell me I'm stuck dragging this thing to a dealer.

Resetting the system via disconnecting the battery takes longer than ten minutes. Leave it disconnected overnight and remove all doubt.

I already unhooked it for an hour and let it sit. Plus there was the couple hours it was unhooked while I was working before all this started.

Check grounds. Check PCM relay.

Ruger said:

Resetting the system via disconnecting the battery takes longer than ten minutes. Leave it disconnected overnight and remove all doubt.

Click to expand...

Yeah, I let it sit overnight. Tried re-programming the keys again. No dice.

xtela said:

Check grounds. Check PCM relay.

Click to expand...

Grounds are all good. Relay seems fine. Coil works and <1Ω on the contacts.

It's going to the dealer first thing tomorrow morning, I guess.

I dont know if it has same PATS system as my 02 lightning did. If you have key in ignition and disconnect battery and then reconnect battery with key still in ,it will trigger the anti theft. The only way to reset it is , a locksmith may be able to do it, or tow it to dealer and have it reset. Problem is not on disconnect but on reconnecting with key in. I almost did this a few times accidently. I leave my key in cup holder now while working on truck.