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Robert R
Robert R, ASE Certified Technician
Category: Jeep
Satisfied Customers: 4534
Experience:  ASE Master Certified, Jeep Certified
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I put an invalid key in the door and the theft alarms system

Customer Question

I put an invalid key in the door and the theft alarms system came on. Now when i use a valid key, the car remains locked. Curious how to unlock my car!
JA: How many miles are on the car? Has this ever happened before?
Customer: 53,000.
JA: What is the model of your '53 Jeep?
Customer: no
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: No, 53,000 miles. 2002 Jeep grand Cherokee
JA: Anything else you think the mechanic should know?
Customer: no
Submitted: 1 year ago.
Category: Jeep
Customer: replied 1 year ago.
I have two valid sentry keys and one invalid key. Just want to start the car with a valid sentry key. I need to disarm the theft security system.
Customer: replied 1 year ago.
I do not have the keyless fob, just the sentry keys.
Expert:  Robert R replied 1 year ago.

Hello, welcome and thanks for asking your question. My name is*****'m a Certified Auto Technician with 29+ years experience. I will do my best to assist you. please keep in mind that I may need to ask questions of you before I can answer. When you reply please feel free to add as much detailed information as possible pertaining to your concern.

You stated: "Now when i use a valid key, the car remains locked. Curious how to unlock my car!"

Are you saying that you are unable to unlock the doors with a valid key? OR are you stating that when you use the key in the ignition the engine fails to start?

Keep me posted...

Thank you,


Customer: replied 1 year ago.
I placed an in valid key in the door, activating the alarm system. Now when I put a valid key in the ignition, all the lights go on including a symbol of a key with slash through it. I need to reset the alarm system.
Expert:  Robert R replied 1 year ago.

There is no published way to "reset" the alarm system. Normally when the key with a slash through it is illuminated with a valid key means that either the valid key is bad or there is an issue with the Immobilizer System. There is one thing that you can do that may or may not reset the system. Go ahead and disconnect the vehicle's battery for 10 minutes or so then reconnect it. After that try to start the engine to see if you are successful. If it starts now I would definitely still recommend that you visit your local dealer and have it diagnosed. If it did this once, chances are that it can happen again.

If it still won't start, you will have no choice but to tow it to your local dealer for diagnosis and repair. I HIGHLY recommend the dealer because if the SKIM module is faulty and needs to be replaced it WILL need to be programmed by the dealer and the keys will also need to be reprogrammed to the vehicle so be sure to take all keys with you to the dealer.

Keep me posted and let me know if you have any additional questions...

Thank you,


Customer: replied 1 year ago.
How do i disconnect the battery?
Expert:  Robert R replied 1 year ago.

The battery is under the hood. You will need basic hand tools to loosen the negative battery terminal and remove it from the battery. Leave it off for a few minutes before reconnecting it to retest starting.

Here is a pic of a battery:

--->> Click Here to view <<---

It may not look like yours but as you see there are terminals connected to the battery, the positive is the plus or one with the red cover. Remove the negative one to avoid damage from arcing electrical sparks.

Customer: replied 1 year ago.
Okay. The metal thing on the opposite side f the red/plus housing?Do i need tools and is this dangerous?
Customer: replied 1 year ago.
OKAY, only the negative, right?
Expert:  Robert R replied 1 year ago.

Yes, you need the appropriate wrench., 10mm, 12mm or 13mm, I'm not sure which for your vehicle. As long as you only disconnect the negative and NOT the positive all should be ok and not dangerous. Although you must make sure not to touch any metal to the positive and negative cable or body at the same time. A spark can occur that may cause fire if not careful..

Yes, correct, only the negative cable...

Keep me posted...

Thank you,


Expert:  Robert R replied 1 year ago.


I just wanted to check in with you to see if you need more help with your concern. A non rated question normally times out within 7 days, so I wanted to stay in contact with you to see if the problem has been solved.

If I have helped you resolve your concern and you have already rated my response, I want to say "Thanks, ***** ***** you know you can still follow up on this concern if needed. Also to let you know you can bookmark >>> My Profile Page <<< in case you have another automotive question in the future. Make sure to begin your question with "Robert R" so I will be able to easily find it

If we are still working on your concern, please post a reply so we can continue.

If you are happy with my answer and have not rated my response, please do so asap to complete the transaction. It is greatly appreciated as I recieve no compensation until you do so...

If you're not satisfied with my answer, BEFORE rating, please post a reply with a short explanation as to why. I may have a better explanation for you... It also helps me to refine my answers to help future customers more thoroughly and efficiently.