I have a '08 Q7, I unlock the car with a key, but can't ignite it by stepping on brake n push the start button. It can't locate the key, usually end up pluggin the key in. What's the problem?

1 Set the emergency brake.
2 Insert key into the ignition and turn the ignition switch to the "ON" or "RUN" position. It is not necessary to start the engine.
3 Locate the shift lock override slot located on the shifter console near the shifter lever. Normally, the slot is plugged with a small plastic cap. Remove the cap.
4 Insert a small screwdriver, nail file, key or similarly shaped object into the override slot, push down and hold
5 While continuing to hold down the shift override mechanism, depress the brake pedal.
6 Now, grasp the shifter, push in the release button located on the shifter as you normally do and then move the shifter to the desired gear. If you've completed these steps with the engine off, move the shifter to the Neutral position to start the engine.

Dont know if this helps

All Volvo cars use the same procedure:

1. Start with the key out of the ignition, drivers door is open all others closed and
drivers door is unlocked.
2. Perform these steps within 5 seconds.
A. Insert the key into the ignition and Pull key out twice (Do NOT Turn)


3. Perform these steps within 40 seconds.
A. Close then open the drivers door twice.
B. Insert the key into the ignition(Do NOT Turn) Pull key out.
4. Perform these steps within 40 seconds.
A. Close then open the drivers door twice.
B. Insert the key into ignition and leave it in ignition.
C. Close the drivers door.
D. Turn the ignition to ON (Do NOT Start) then back to OFF.
E. Remove the key from the ignition.
5. Within 3 seconds, the power door locks should lock then unlock automatically
indicating successful entry into programming mode.
Return to step 1 if the locks do not cycle at this point.
6. Perform these steps within 40 seconds.
A. Press the lock and unlock buttons on the remtoe simutaneously for 1.5 seconds.
B. Immediately after letting go of the lock and unlock buttons,
Press the lock button by itself and hold for 2 seconds. Within 3 seconds, the door
locks should lock and then unlock once indicating successful programming. If
the door locks cycle twice, repeat steps A and B in step 6 as the remote was
not accepted.
C. Repeat steps A and B in step 6 for each new remote.
7. Open drivers door.

Whether your key fob is damaged or just has a dying battery, there is a way for you to unlock your vehicle and start the car. Just follow the steps below:

1. Press and hold the auxiliary key release button on the underside of the key fob.
2. Grab the looped end at the top of your key fob.
3. Pull out the auxiliary key.
4. Use the auxiliary key to unlock the driver's side door.

[Read more: What to do when you're locked out of your car]

HOW TO START THE MAZDA 3 WITH A BROKEN OR DEAD KEY

Now that you've managed to enter the vehicle with the auxiliary key, you're going to need to know how to start your Mazda 3. At this point, the auxiliary key can be put back into the key fob, as the key fob can still be used to start your vehicle. This will only take a few extra steps.

1. Make sure the shifter is in the Park (P) or Neutral (N) position.
2. Depress the brake pedal.
3. The light on the engine start button should flash green.
4. Take your key fob and touch the back of it to the push button start.
5. When the green light on the engine start button stops flashing and remains continuously illuminated, press the push button start normally to start the engine.
6. It is recommended you allow the vehicle to idle for about 10 seconds.

Sounds like you have a key without the chip in it. Replacement keys without the chip will only unlock the doors and will activate the theft alarm when you start the vehicle.

1. sitting in driver seat, with driver's door OPEN, press lock/unlock button ON THE DRIVERS DOOR to lock all doors, then manually unlock driver door only.
2. Insert YOUR key in ignition, DO NOT TURN, then remove key.
3. Using the same lock/unlock button ON THE DRIVERS DOOR, slowly press lock-unlock in 5 cycles
4. Shut door.
5. Open door.
6. Using the same lock/unlock button ON THE DRIVERS DOOR, again slowly press lock-unlock in 5 cycles
7. With the door open insert your key into the ignition, turn to 'on' position (DON'T START), wait 5 seconds. Turn off and remove key.
8. Locks should cycle once (Car will lock and then unlock once by herself). If they don't cycle or they cycle more than once, do steps 1-7 over.
9. Now using the remote, push lock button, hold for one second, then release the button. The locks should cycle once. If not, start over and go slower.
10. Close the door.
11. Open the door.
12. Press the lock button on the remote. The locks should do a lock-unlock cycle.
13. Close the door
14. Press the lock button on the remote, the doors should lock.
15. Press unlock button and the doors should unlock.

Remote Programming Instructions

1. Driver's door OPEN and unlocked, all other doors closed and locked.

2. Insert YOUR key in ignition, DO NOT TURN, remove key.

3. Using the MANUAL lock/unlock button ON THE DRIVERS DOOR, slowly press lock and unlock 5 times (count the lock 5 times and unlock 5 times).

4. Shut door.

5. Open door.

6. Using the lock/unlock button ON THE DRIVERS DOOR, slowly press lock and unlock 5 times (count the lock 5 times and unlock 5 times).

7. With the door open insert your key into the ignition, turn to on position (DON'T START), wait 5 seconds. Turn off and remove key.

8. Locks should cycle once (Car will lock and then unlock once). If they don't cycle or they cycle more than once, do steps 1-7 over.

9. Now using the remote, push lock button, hold for one second,
release. The locks should cycle once. If not, start over and go slower.

10. Close the door. Open the door. Press the lock button on the remote. The locks should cycle. Close the door. Press the lock button on the remote, the doors should lock. Press again and the doors should unlock.

Program your factory keyless entry functions
For 2001+ Tacomas equipped with a factory alarm or keyless entry, here are some programming options that allow you to adjust the way your locks work.
The first programming option allows you to set the entry unlock to: (A) unlock the driver door with one push, and the remaining doors with a second push OR (B) unlock all of the doors with a single push.

• Open the driver's door. Remove the key from the ignition switch.
  
• (Complete these steps within 40 seconds)
  
  1. Insert the key into and remove it from the ignition switch 2 times.
     (IN - OUT - IN - OUT)
     
  2. Close, then open the driver's door 2 times.
     (SHUT - OPEN - SHUT - OPEN)
     
  3. Insert the key into and remove it from the ignition switch 1 time.
     (IN - OUT)
     
  4. Close, then open the driver's door 2 times.
     (SHUT - OPEN - SHUT - OPEN)
     
  5. Insert the key into the ignition switch and leave it in.
     
  6. Close the driver's door.
     
  7. Turn the key from LOCK to ON 4 times, ending at LOCK
     (LOCK - ON - LOCK - ON - LOCK - ON - LOCK - ON - LOCK)
     
  8. Wait for the locks to stop, then remove the key from the ignition switch.
     
• On the key fob, press and release both LOCK and UNLOCK buttons at the same time.
  
  1. [For all doors unlock] press and release the UNLOCK button.
     
  2. [For driver door unlock] press and release the LOCK button.
     
• Open the driver's door. The programming is complete. If programming did not occur, start over.

I have an A4 and did this to re-program my key:

1. used the key to start the car...then turned it off
2. put the key in the driver door (door closed)
3. pressed the lock button on the key fob once
4. turned the key to lock the door.

This is basically the steps in the owners manual, but the car must be started with the key first, and the key must be in the door lock before pressing the lock button.

that´s low batery, you must take out the smoke kit front of the gear knob, and ther´s a button to unlock the key.
sorry my english, i am form Uruguay, south america.
good luck.