2005 Corolla Immobilizer Self-Immobilizes - Toyota Corolla, Chevy Prizm (1998-2008)

My immobilizer kicked in on its own (no electrical power at all). A couple lock/unlock on the fob and a couple of door open/close/lock/unlock got the alam going. I clicked unlock to stop the alarm and then turned key to on and I had dash lights. As soon as I turned to ignition everything died again. I did this several times over with the same results each time. I googled my problem and at a site before I found this one suggested disconnecting the battery for 10-20 mins to allow the immobilizer to reset. When I reconnected the battery the alarm came on and I used the fob to shut it and tried the key. It worked and I have started and stopped the car several times. But now there is a rough slower idle (between 500-600) which has occurred before and then becomes the regular 800 idle after some miles of driving and some hours. I haven't driven it yet so don't know if it will go away this time. Any ideas for a fix - I don't want to get stuck in West Podunk if the immobilizer refuses the reset trick. Thanks.

Just make sure the remotes batteries are fresh - if the voltage drops even a bit, they can act a bit weird. If these are the original batteries - you're probably be on borrowed time.

As for the idle issue - that is likely a different problem. Disconnecting the power will erase the ECM stored parameters - so it will take a little bit of time for it to "relearn" and drop into a good operating mode. Also, since this model was the first year they used DBW - might be that the throttlebody will need to have a recalibration done. Not sure if this procedure works on a 9th gen Corolla - but might be worth a shot:

1: Key to "ON" (not start)

2: Push accelerator pedal all the way to the floor and hold it there

3: Hold for 5 seconds

4: Key to "OFF" while still holding pedal

5: Release pedal, restart car normally and see if the throttle and idle are "fixed"

Thanks fishexpo101 for your answer - I will get the fob's battery replaced. As for the idle problem it is still there after two separate recalibration attempts. Haven't driven the car anywhere yet so it might just need some stop and go driving to relearn - I'll repost after I've had it out on the road.

fishexpo101 - sorry so long for follow-up - did get the fob's battery replaced and so far no immobilizer problem (even though toyota parts guy said there shouldn't be any connection). as for the idle problem i took it to my mechanic and he cleaned the dirty throttle plate and throat and fixed it no charge. thanks for your info and helpful suggestions - joe