The security lights blink when door is opened is there a sensor bad?

Has your car been in an accident or hit from behind lately?

Could be two problems,bad switch driver door[blinking],could be four way switch[clicking].

anit theft is activated. It should deactivate if you close all doors and hood and open with key or fob from outside of truck.

You must have opened a door by reaching inside and opening the door when it was locked. Once locked, it msut be unlocked with key or fob so the ouside lock sensor will tell the module it was unlocked porperly. Or, you have a bad door lock sensor switch.

I think you have to have the key in the ignition, and set to "ON" with the driver door open and holding the unlock button down for several seconds. At least that works on my Forester.

I had this same exact problem in a family member's Saturn. If you are opening the door with the key and not using the key FOB to unlock the doors, then the security system will not allow you to start the car. You will notice when this happens that the dome light will blink and you'll hear the relay in the BCM clicking.

In order to stop the security system from doing this: Make sure the car is locked with the key fob by hitting the lock button. Then hit the unlock button on the key fob once and then once again (I do it out of habit). Then open the driver side door, put the key in and it should start no problem.

try spraying WD40 into the latches and open and close the doors a bunch of times

I have the same problem with my 93 Jeep Grand Cherokee.  I assume this is the security system and for what ever reason it is going off.  What I do is hook the battery back up which makes the lights flash and then put your key in a LOCKED door and open the door with your key.  This should shut off your security system and allow the vehicle to start.  

Good Luck

The cam sensor is in the head near the throttle cables. The crank sensor is in the block near the oil filter. There aren't any sensors behind the balancer. If it is a problem with the security system the security light will be blinking. Does the vehicle start and die or just not crank or crank but not fire?

Make sure your hood is shut. I just got my 2002 Honda Odyssey back from the dealer today (90,000 mile check-up - I love my van and will drive it until it dies!) and when I went to lock the van with my remote transmitter, the lights didn't flash and the horn didn't sound. I open and closed all the doors and tailgate and I could hear that the doors were locked, but the security system wasn't working and that is why the lights didn't blink or the horn didn't sound. I walked up to the front of the van to check the hood to make sure it was closed (there isn't an indicator light for an open hood, only open doors) and the hood wasn't shut completely. Once I opened the hood and let it drop to securely shut, I hit the door lock button on the remote and everything worked like a charm! Hope this helps others in this predicament.

Sounds like your Passlock security system went into the tamper mode. If your dashboard security light blinks when the ignition is turned on, your Passlock security system is disabling the injector module, preventing the car from start. Try this:
1- turn the ignition on and just touch the starter, without getting the motor to fire, then leave the ignition in the "on" position. The security light will blink for about 10 minutes. When the light stops blinking, turn the ignition off and leave off for 3 minutes.
2-repeat the step #1, 3 or 4 times. You will know that is fixed when you turn the ignition on and the security light does not blink, then the car will start. Make sure to stay inside the car when you're doing this, as opening the doors will trip the security tamper mode on again. Once the tamper mode is off, the car starts and opening the doors will not trip the Passlock tamper mode.