In my research to figure out how to program keys to my LC I have compiled the following steps for all model year 100 series. I am posting this so that all steps for all models can be found in one list. Please note there are other variations that may work fine, but the below seem to work every time from posts I have read. Hope it helps.
The below information applies to the 4C and 4D transponder keys. The 4C is 1998-2002 also referred to as the “sequence E” programming steps; all steps below work for programming that key. The 4D chip is for 2003+ 100 series, also referred to as “sequence I” programming steps; many steps below will work for all 03+, however the ECU can not be programmed for 03-04 start capability without a computer per FSM (05+ should program with these steps from what I have read).
Also, please note that timing is critical, you must be spot on. If a sequence fails try again making sure the timing is exact. If you are still unable to program the new key into the ECU you may have too many keys programmed; there can be up to 5 master keys and 3 valet keys (per 03-04 FSM). If unsure you can clear all but one master key and program/reprogram any existing keys.
Tell what key you have:
To determine if the key(s) have been properly programmed into the ECM you may utilize the following procedure:
Positively locate the “security” or “anti-theft” light. This light should blink when there is no key in the ignition or if an unrecognized key is placed into the ignition.
Insert the key you have into the ignition – DO NOT TURN ON. There are 3 possible things that may occur:
Security light continues to blink = unrecognized key.
Security light goes off IMMEDIATELY = MASTER key
Security light remains illuminated for 1-3 seconds before going out = VALET key
***FOR ALL PROCEDURES BELOW make sure you start with the following steps unless otherwise stated:
All windows are up
All doors are shut and locked except for the drivers door which should be unlocked
Delete all but one master key:
To delete all but one key from the unit (ECM):
Simultaneously depress and release brake and accelerator pedals 1 time.
Insert an existing master key into the ignition cylinder. Do not turn the key from the OFF (LOCK) position.
Within fifteen seconds of inserting the key, depress and release the accelerator pedal six times.
Within twenty seconds of completing the above step, depress and release the brake pedal seven times.
The security light will flash, indicating all keys other than the one being used have been deleted.
Remove the key from the ignition cylinder within ten seconds.
***Alternative method possibly for sequence I vehicles (2003+)
Insert Master Key and Cycle ignition 6 times (Lock to on then back to lock)
Within 35 seconds open and close Drivers side door 7 (seven) times.
Remove the key from the ignition cylinder within ten seconds.
Program new key (sequence E):
Simultaneously depress and release brake and accelerator pedals 1 time.
Insert existing master key into ignition.
Within 15 seconds depress and release accelerator pedal 5 times.
Within 20 seconds depress and release the brake pedal 6 times and remove key.
Within 10 seconds insert new key into ignition.
Within 10 seconds depress and release the accelerator pedal 1 time.
After 80 seconds new key is registered and security light goes off.
Remove new key and depress and release brake pedal 1 time.
Program new key (sequence I – 2003+):
Simultaneously depress and release brake and accelerator pedals 1 time.
Insert existing master key into ignition.
Within 15 seconds depress and release accelerator pedal 5 times.
Within 20 seconds open and close the “driver side” door 6 times and remove key.
Within 10 seconds insert new key into ignition.
Turn the ignition cylinder ON and leave on for two minutes.
Turn ignition cylinder OFF and remove new key
Open and close the “driver side” door 1 (one) time.
After 60 seconds new key is registered and security light goes off.
Remove new key and depress and release brake pedal 1 time.
Erase Remote Procedure (years this works on unknown):
Make sure no keys are in the ignition lock and the drivers door is open and unlocked.
Put the key in the ignition and remove it.
Press the lock button for 1 second, press the unlock button for 1 second and repeat 5 times.
Close the drivers door and open it.
Press the lock button for 1 second, press the unlock button for 1 second and repeat 5 times.
Put the key in the ignition.
Turn ignition ON for 1 second and then off for 1 second then on for 1 second and remove key.
The power door locks should cycle 2 times.
Press the lock and unlock button for 2 seconds, then press the unlock for 1 second.
If the remote is programmed the doors will cycle once. If failed the doors will cycle 2 times.
Open drivers door to end procedure.
Program Remote: (sequence E)
1. Start with key out of ignition, drivers door is open all others closed and driver’s door is unlocked.
2. Insert key into the ignition (Do NOT Turn) and Pull key out.
3. Perform these steps within 40 seconds.
Using the power lock switch on the drivers door, perform 5 lock/unlock cycles starting with lock. Use an even pace and try to go about one cycle per second. (1Cycle = 1 lock and 1 unlock).
Close, then open drivers door.
4. Perform these steps within 40 seconds.
Using the power lock switch on the drivers door, perform 5 lock/unlock cycles starting with lock. Use an even pace and try to go about one cycle per second. (1Cycle = 1 lock and 1 unlock).
Insert the key in the ignition cylinder.
Turn the ignition to ON (Do NOT Start) then back to OFF.
Remove the key from the ignition.
5. Within 3 seconds the power door locks should cycle 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.
Press the lock and unlock buttons on the remote simultaneously for 1 second.
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 cycle once indicating successful programming. If the door locks do not cycle, or cycle twice. Repeat steps A and B in step 6 as your remote has not been accepted.
Repeat steps A and B in step 6 for each new remote.
7. Close drivers door.
Program Remote: (sequence I – 2003+)
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.
Insert the key into the ignition(Do NOT Turn) Pull key out.
Insert the key into the ignition(Do NOT Turn) Pull key out.
3. Perform these steps within 40 seconds.
Close then open the drivers door.
Close then open the drivers door.
Insert the key into the ignition(Do NOT Turn) Pull key out.
4. Perform these steps within 40 seconds.
Close then open the drivers door.
Close then open the drivers door.
Insert the key into ignition and leave it in ignition.
Close the drivers door.
Turn the ignition to ON (Do NOT Start) then back to OFF.
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.
Press the lock and unlock buttons on the remote simultaneously for 1.5 seconds.
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.
Repeat steps A and B in step 6 for each new remote.
7. Open drivers door.
Now, my sensor is is out of the case and I use it to lock/unlock the vehicle. Luckily I have a vaket key. The problem I have is the master key that broke will no longer start the vehicle! It just continually turns over and over. Does the computer know if the sensor is no longer right next to the key? If I buy a new case and drop in the sensor and have it cut off the old master should the trick this do?
