Yesterday afternoon, when I opened the door to get into my Jeep, the headlights started flashing, the horn started blowing, and the engine would only run for a few seconds.  It did this to me back in June also.  At that time, the local stealership said that the problem was that low voltage had caused a relay in the system to stick and activate the alarm.  I know a little about electronics and that is a bullshit answer.  I did not try to start the Jep with my spare key, just the one I always use.  Unhooking the battery made the alarm quit going off until I opened the door, and then it started again.  The doors were not locked when it started this foolishness.

Anybody have any ideas on this thing?

Thanks,
John

I'm pretty sure the dealership got it wrong the last time if that's what they repaired. If the relay was STUCK it would NEVER stop until it burned out, blew a fuse, or killed the battery.


Grand Cherokees have a switch(actually two, maybee even three, I don't remember) that disables the factory alarm.

If you change the relays in the anti-theft system it won't help in this case. There will always be a 'tripped' alarm switch, causing it to activate the anti-theft system over and over.


Before you disable or repair the system, first try this; Go to each door and using your key, lock, then unlock them one at a time to see if it shuts the alarm off. Make sure the hood is closed. Then, if that doesn't work go to the rear hatch and try the same thing.

If it still doesn't start and the lights are flashing, horn still going, then you most likely have a bad switch, these switches are flimsy junk that attach to the inside of the door lock behind the door panel. A very poor design.

There is no way to tell which one is causing the problem, so you have to start on one side and check until you find the bad one. Most of the time they simply fall off the lock due to the crappy design. You are looking for a small round electrical part with a two wire connector, they are about the size of a nickel in diameter and usually white. I don't recall the wire colors, but it will be on the back of the lock or if it fell off, hanging inside the door panel.

The switch is activated and deactivated when you turn the door lock with your key. The switch has a rotating center that turn with the lock. It's either on or off, so if it fell off the back of the lock in the 'ON' position the anti-theft sytem is completely activted, and most of the time it will stay activted even if the second switch inside the other door is working. There doesn't seem to be an override in case one switch fails, at least that's been my experience.


TESTING AND REPAIR:

Remove one front door panel, any side is fine, you have a 50-50 chance of getting it right the first time.


If you found that the switch just fell of the lock

1) Leave the switch connected to the harness then take a screwdriver and turn it to the other side. This should deactivate the switch and turn off the alarm so you can start you car now. If it starts you need to re-attach the switch, most of the time you need to order a new one because the clip broke.

2) If it didn't start, remove the electrical connector from the switch and place a jumper wire between the two terminals of the connector and try again. If it starts now, you can order a new switch from the dealer, or better yet, cut the connector off and twist the two wires together to permanently disable that switch so it doesn't cause problems again. Tape them up and just make sure they are out of the way from the lock and window.



If the switch was still connected when you opened the front door panel.

1) Carefully remove the connector from the switch, jump out the connector as described above. If th car starts you need a new switch.

2) If it doesn't start you must re-connect the electrical connector to the switch and remove to the other front door panel. Now you have to start testing the switch on the other side, just go step by step until it starts.



One more thing to consider, although extremly rare, I have seen electical shorts in the switch circuit which must be traced to the problem spot and fixed as needed, but 90% of the time it's the switch itself.

Also, there may be an additional switch on the back of the rear hatch lock, you wouldhav to remove the rear hatch panel to access it. I don't recall if there is one because I work on so many makes and models that I can't memorize every location, but if there is, you would check it the same way as the front door switches. Luck would have it that I troubleshot, fixed or disabled a number of these systems over the last year so it's still fresh in my mind.




Good luck.

Thanks for the suggestions.  I'll take a look at the things and see what I can find.

John