If it's p1668, there is a possibility that your ECM and BCU aren't talking to each other anymore. The engine starts, and then immediately dies because the security codes cannot be confirmed. I'd make sure the battery is fully charged. Maybe check fuses and wiring too. Also look for signs something got wet. I got that code when my computers got wet.

 

Everybody is right - a normal battey swap won't cause a problem. In this case seems like immobilization is in effect. Maybe truck thinks it was locked before old dead battery was "discovered" and now thinks it is under attack. Always a good idea when installing battery to depress bonnet switch. Try switch on ignition without cranking and leave for 5 minutes. And try arm/disarm with key fob like 10 times.

From page 352:

P1668 Engine anti-theft signal circuit high Serial link open circuit


status of the security system can only be interrogated using TestBook.



From RAVE:
(page 1288)

The ECM memorises the positions of the crankshaft and the camshaft when the engine has stopped via the CKP and CMP sensors. This allows immediate sequential fuel injection and ignition timing during cranking. This information is lost if battery voltage is too low (i.e. flat battery). So the facility will be disabled for the first engine start.

IMHO the BCU and ECU may forget more than is explicitly listed in the RAVE. But trying the resync option above is certainly cheaper than a tow to the dealer. "Re-learning idle" might be a myth based in this case of trying long enough to equal 5 minutes (maybe it takes less, who knows?). I disconnected my hood switch because I read so many posts from people with alarm / immobilize problems. Just not worth it. Of course I don't live near the Clinton Library, where the best mechanics in Little Rock chill, they have to take their engine blocks inside every night.....

 

This happens ALL the time, leaving the truck without power for to long will cause the ECU to loose its memory.
As far as I know the only way for it to get it back is from a tech with the correct computer to plug in and re-flash the ECU and make sure the alarm and ECU are synced.
People have been on here before bringing a truck that has sat for a year back to life and having similar problems.
It is NOT the battery that is the problem, it is the ECU.
I suppose you could just keep starting the truck and seeing if the ECU eventually picks up the idle and it stays running.
But my best advice right now is to have it flat bedded to the dealer and have them re-flash the ECU.
Best of luck and PLEASE report back when you get it going.

 

If you turn your key on and the check engine light wont come on, I believe its immobilized. BTW I had a bunch of "bro" shiit hooked up to my car when I was 17 too! The stickers are mad phat yo. And what colors are that cool *** transformer plate sticker? Zimbabwe flag? I also find it humorous / ironic that your car is broken, and your battery says "game over".

 

morons like you are the reason i normally stay off or forums...

 

This post has given me a good laugh or two...lol
Punisher more than likely has been given the information that he needed and insulted Mike along the way....
Kids these days...lucky guy though, Mike, Buzz, Spike and Master all chimed in to help out.
Nice.

 

and all of them were wrong with saying the battery could not cause this problem, the problem has been fixed.. the computer sat to long with out power and lost its memory, just like mike said it could not.. memory reset now and truck is perfect again...

 

thanks spike jfir, and savannah i appreciate the help with out the dumb comments, you 3 were a big help..

 

go buy some more bubble gum stickers. and like you said it wasnt the battery you it the LR tech said it happens all the time. it lost its idle yea ok but the LR tech wasnt smart enough to fix it? or have a solution for you? like the other guys said we all been 17 before BRO.. but back when i was a kid, I had large respect for knowledge which usually came from elders and not the bros or the $200 an hour LR techs.
thx to this forum you learned that it indeed was a security issue, instead of pushing your wrong you should have been all ears. come back in 20 years and we can talk more.. you will hopefully grow into a man someday but until then dont point fingers or try to wrong people that actually tried to help you.
take it how you want to, my 2 cents, maybe 1/8th of it will stick and you will thank me in 20.

my 2 cents..

 

after the dust has cleared, what had to be done to make the truck return to normal?