1. Honda Immobilizer

2. 1949 Chrysler, first with starter switch in ignition key
Probably the best theft deterrent device for the automobile came out in 1949, when Chrysler offered the combination key-operated ignition and starter switch, which is still in use today. Previously, the starter was operated by a separate button on the dash. And then in 1970, the government mandated steering wheel interlocks that locked the steering wheel when the ignition key was removed.
1949 Chrysler, first with starter switch in ignition key

3. Theft deterrent passively or actively interrupts a circuit in the ignition, fuel, or start circuit.
Theft deterrent passively or actively interrupts a circuit in the ignition, fuel, or start circuit. A key with a transponder is used.
Description
The immobilizer system further builds upon the theft deterrent key operated ignition switch. Immobilizers work by automatically, or passively, interrupting the power to one or more electronic circuits, usually the starter, ignition and fuel circuits, unless a specially coded key is used in the ignition switch. These keys typically employ a transponder or resistor embedded in the head of the key that communicate a code to the engine management system and allow the engine to start.
If the correct code is not recognized by the system, or some other means is attempted to start the vehicle such as hotwiring or breaking the ignition lock cylinder, the system will remain armed and prevent the vehicle from being started.
Only if the correctly coded key, or other coded element is used and recognized by the system, will the circuits be enabled, allowing the vehicle to start.

4. The key must be recognized in order for the vehicle to start.

5. 6 Immobilizer types 6 Immobilizer types
1 & 2 are unique systems that operate similary
2 & 3 are identical in construction but function differently with different keys.
5 & 6 are identical in construction with different functions
System Types
There are 6 types of immobilizer systems used by Honda, and the systems are all very similar in design.
Type 1 and Type 2 are both unique in construction and function. Types 3 and 4 are identical in construction, but function differently and use different keys. Types 5 and 6 are identical in construction, but they function differently.
The basic components of an immobilizer system are a transponder key, a receiver, an immobilizer control unit, and the ECM/PCM.

6. Basic immobilizer components: Key/transponder, lock cylinder (transceiver/receiver), Immobilizer control unit, ECM/PCM
Basic immobilizer components: Key(transponder), lock cylinder (transceiver/receiver), Immobilizer control unit, ECM/PCM

7. Transponder Key does not contain batteries
There are no batteries or other serviceable parts inside these transponder keys. The power for the key's transponder code is supplied at the ignition switch.
Each key has a built-in transponder in the grip that contains an integrated circuit with a unique ID code. There are ID codes numbering in the billions available in the integrated circuit, so each key will have a different ID code. This ID code has to be programmed into the immobilizer control unit so that when the key is used in the ignition, the engine will start.
Immobilizer keys for Types 1 through 3 systems use a set code that does not change while immobilizer keys for Type 4 through 6 systems use rolling code technology to roll the code over to a new code each time the vehicle is started.

8. There are billions of ID codes.
There are billions of ID codes. Key code must be programmed into the control unit. Key is supplied power by the ignition cylinder (electromagnetic induction)

9. Each system has a receiver unit which is an antenna attached to the ignition switch.
It uses electromagnetic induction to energize the transponder in the key when the ignition switch is turned to ON.
Fixed or rolling code (new code on every start up)

10. Receiver unit energizes the transponder (key) and the transponder transmits the key code to the immobilizer control unit.
Receiver unit energizes the transponder (key) and the transponder transmits the key code to the immobilizer control unit.

11. The ECM/PCM receives the unique serial code from the immobilizer control unit
When the ECM/PCM receives the unique serial code from the immobilizer control unit, it communicates, or "handshakes" with the immobilizer control unit by sending back its own unique serial code. If the serial codes are mutually recognized during this handshaking process, the ECM/PCM enables the fuel supply circuit at the fuel pump so the engine can start.
The immobilizer control unit sends power to the receiver to energize the transponder in the key.
It then gets the key's transponder ID code from the receiver, and checks it against the codes programmed in memory. If the code matches, it sends a unique serial code to the ECM/PCM. If the code does not match, no serial code is sent.
The receiver sends the ID code to the Immobilizer control unit.

12. Immobilizer control unit sends a unique serial code to the ECM/PCM
If the cod e matches the ID that is stored, the immobilizer control unit sends a unique serial code to the ECM/PCM. No code is sent if it does not match.

13. ECM/PCM confirms the ID code, it sends a ‘handshake’ back to the immobilizer control unit
Once the ECM/PCM confirms the ID code, it sends a ‘handshake’ back to the immobilizer control unit.

14. Serial codes are mutually recognized, the ECM/PCM enables the fuel system
If these serial codes are mutually recognized, the ECM/PCM enables the fuel system

15. Type one system, disables start and fuel
Type one system, disables start and fuel if an unrecognized key is used.
Type 1 Immobilizer System
Type 1 systems use an immobilizer receiver connected to an immobilizer control unit that is connected to the starting circuit and the ECM/PCM. If an unrecognized key is used, the starting and fuel supply circuits are disabled, and the engine will not crank.

16. Type 2 systems use a receiver connected to the immobilizer control
unit which is built into the ECM/PCM
Type 2 systems use a receiver connected to the immobilizer control unit which is built into the ECM/PCM. If an unrecognized key is used, the fuel supply circuit is disabled, and the engine will crank, but not start.

17. Type 3 and 4 systems use an immobilizer control unit and a receiver built into one unit
Type 3 and 4 systems use an immobilizer control unit and a receiver built into one unit and connected to the ECM/PCM. If an unrecognized key is used, the fuel supply circuit is disabled, and the engine will crank, but not start.

18. Type 5 and 6 systems use a combination immobilizer control unit & receiver along with an additional security IMOES unit (immobilizer entry system)
Type 5 and 6 systems use an immobilizer control unit and a receiver built into one unit along with an additional security unit called the Immobilizer Entry System, or IMOES unit. Both units are connected to the ECM/PCM. The IMOES unit receives the key's transponder ID code from the immobilizer control unit-receiver and determines if the ID code is correct. If the ID code is correct, it signals the ECM/PCM that it received the correct ID code so that the ECM/PCM will enable the fuel supply circuit if it also received a correct ID code. If an unrecognized key is used, the fuel supply circuit is disabled, and the engine will crank, but not start.

19. Type 6, engine start then code is checked, no match = engine dies
To improve the customer?s perception of hard starting, which was associated with the system determining if a correct key was being used before starting the engine, Type 6 systems function differently.
On this system, the vehicle starts before the system checks if a correct key is being used in the ignition. If a correct key is used, the engine stays running, but if an incorrect key is used, the fuel supply circuit is disabled within 2 seconds, and the engine shuts off.

20. Signal from the keyless access control unit is sent out to the ECM/PCM and IMOES
Please note that Honda has also started introducing keyless access so that a key is not needed to start the vehicle. In this case, a signal from the keyless access control unit is sent out to the ECM/PCM and IMOES unit instead of from the immobilizer control unit ? receiver. If for some reason the keyless access is not working, the keyless access remote has a built in transponder key that can be used start the vehicle.

21. Master key with black grip: ignition, door, trunk, & glove box
Master key with black grip: ignition, door, trunk, & glove box. Valet key with gray grip: Ignition & door locks
There are two kinds of keys used for starting the vehicle. The master key with the black grip is for the ignition, the door and trunk locks, and the glove box. The valet key with the gray grip is for the ignition and the door locks only. This key is meant to be given to valet parking so your valuables in the trunk and glove box are kept safe if locked. Also note that some keys have the keyless remote transmitter built-in.

22. traditional key and the sidewinder key (2002 & later)
Matrix H Key Cutting Machine
Required for Sidewinder Key
There are two different types of keys used by Hondas, the traditional key and the sidewinder key. Starting in 2002, Honda started changing over to the sidewinder-type key because they are harder to duplicate, and require a special cutter, the Matrix H Key Cutting Machine.

23. Type 2 & 3 stamped with a "F" for fixed transponder codes
Type 2 & 3 stamped with a "F" for fixed transponder codes. Type stamped with a "V" for rolling transponder codes
Please note that there are two different types of transponder keys. Type 2 and 3 systems use those stamped with a "F" for fixed transponder codes, while type 4 through 6 systems use those stamped with a "V" for rolling transponder codes. You cannot interchange keys between systems.

24. Type 1 system: 1997 - 2001 Prelude, 1996 - 2004 3.5RL, & 1997-2005 NSX.
Type 1 systems can be found on the 1997 to 2001 Prelude, the 1996 to RL, and the NSX.

25. Type 1: Red learning key puts immobilizer system
into a re-programming mode to add & delete keys.
The red learning key will not start the engine.
On Type 1 systems, a learning key with a red grip is used to put the immobilizer system into a re-programming mode to add and delete keys to and from the system. The red learning key will not start the engine. Advise the customer that the red learning key is only a tool for adding and deleting keys and that it should be stored in its original packaging to prevent accidental use.

26. A lost red learning key requires replacing the immobilizer control unit.
Please note that if the red learning key is lost, replacement or additional keys cannot be programmed into the system. The red learning key has a unique ID code that is matched to the immobilizer control unit, and a replacement key is not available without an immobilizer control unit.
The ilco duplicator can make copies of a programmed key (systems 1-3)

27. Green immobilizer system indicator confirms operation
Green immobilizer system indicator confirms operation. Controlled by immobilizer unit in Types 1 through 5 and by CAN in Type 6.
Immobilizer System Indicator
The results of the immobilizer control unit� can be confirmed by the green colored immobilizer system indicator in the instrument panel. The indicator is controlled by the immobilizer control unit in Types 1 through 5 and by CAN communication in Type 6.
If you insert a key into the ignition that is programmed into the system, and then turn the switch to ON, the indicator comes on for about 2 seconds as the system performs a check, and then goes off. When you turn the ignition switch to LOCK the system resets, and the indicator flashes for 5 seconds, then goes off on Types 1
through 5 systems. On Type 6 systems, the indicator only goes off and does not flash.
If you insert a key into the ignition that is not programmed into the system, and then turn the ignition to ON, the indicator comes on for about 2 seconds as the system performs a check, and then starts to flash. The indicator keeps flashing until you turn the ignition switch to LOCK.

28. Logic table for indicator lamp, all types similar except type 6 does not flash on shut down.

31. Vehicles normally come with three keys
HDS needed to program additional keys
Vehicles normally come with three keys programmed into the immobilizer system, two master keys and one valet key. You can add additional keys to the system using the HDS.

32. If one key is being added, you only need one programmed key from the customer (except Type 1, all programmed keys are needed.)
one key is being added, or programmed into the system, you only need one programmed key from the customer to do this, except on Type 1 systems where all programmed keys are needed.
All programmed keys from the customer are needed for any system Type under the following circumstances: Multiple keys are being added, transponder ID codes of lost keys are being cleared from memory so that they cannot start the engine, or the immobilizer control unit or ECM/PCM is being replaced.

33. At times, all programmed keys are needed for any system
All programmed keys from the customer are needed for any system Type under the following circumstances: Multiple keys are being added, transponder ID codes of lost keys are being cleared from memory so that they cannot start the engine, or the immobilizer control unit or ECM/PCM is being replaced.

34. Type , ‘ilco’ Key Code Duplicator and ‘ilco’ programmable key blanks marked with "T5" can be used to make a duplicate key,
Remember, on Type 1 systems, you need to have the red learning key to add or delete keys. If the red learning key is lost, unprogrammed keys cannot be programmed into the immobilizer system.
You can get around this because on Type 1 through Type 3 systems, an ilco Immobilizer Key Code Duplicator and ilco programmable key blanks marked with a "T5" can be used to make an exact duplicate key, including the transponder ID code, from a key already programmed into the system.

35. Type 1 accept a total of 5 keys, not including the red learning key
Type 1 accept a total of 5 keys, not including the red learning key. Type accept a total of 6 keys.
Number of Keys
Type 1 systems can be programmed to accepts a total of 5 keys, not including the red learning key, and Type 2 through Type 6 systems can be programmed to accept a total of 6 keys.
You can view the number of keys programmed into the system using the Immobilizer menu on the HDS.

38. If no programmed keys, or system failure, you can still start the engine using a cut key blank and a VIN specific Immobilizer ‘Brake Code’
Brake Code
If a customer is stranded because they have no programmed keys, or a part of the immobilizer system has failed, you can still start the engine using a properly cut key blank and a VIN specific five-digit Immobilizer Brake Code to temporarily bypass the immobilizer system. This code is available on the iN Anti Theft Code Inquiry.

39. 5 digit brake code is entered using the ign switch & the parking brake
Entering Brake Code
The five digit brake code is entered using the ignition switch and the parking brake. After the ignition is turned to ON, the first of the five digits is entered by setting and releasing the parking brake that number of times within 30 seconds. For example, if the first digit is three, set and release the parking brake three times.
Turn the ignition switch to ON...
After the digit is entered with the parking brake, turn the ignition to LOCK to enter the digit in the ECM/PCM. You would then turn the ignition to ON to enter the next digit of the Brake Code the same way...
After the last digit is entered, and the ignition is turned to LOCK, wait for the immobilizer indicator to flash five times. The engine then needs to be started within 10 minutes or the procedure will have to be repeated. The engine will continue to restart if no more than 10 minutes elapses since turning the ignition to LOCK. The brake code can be entered an unlimited number of times, however, the system should be repaired to work correctly as soon as possible.
Please note, while in this temporary bypass mode, the immobilizer and brake warning indicators remain ON after the engine is started, even if the parking brake is released.

42. Verify system indicator is working
Cranks no start
Verify system indicator is working
Try using the key only without key rings
or other keys attached
General Checks
When a customer comes in with a vehicle that cranks, but will not start, ask the customer to see their keys and make sure the immobilizer system indicator is working correctly and that the key is a genuine Honda part.
When starting the vehicle, try using the key only and no key rings or other keys attached. The receiver may not recognize the key� coding if another immobilizer key or other metal object is near the key when trying to start the engine.
Then make sure there are no aftermarket electrical accessories like a remote starter attached to the system. Electrical problems could result that may make the vehicle not start.

43. HDS troubleshooting with System Check and Status Log
Some 2005 and later models can use two software items in the immobilizer Test Mode Menu of the HDS to help troubleshoot the immobilizer system. They are System Check and Status Log. The HDS system will tell you if these items are functioning or not for the vehicle when accessed from the Immobilizer Test Mode menu.

44. Results of system check
If OK, System check ‘Immobilizer Normal’

45. Status Log
If a System Check result of “Not Normal” is indicated on the HDS display, check the failure according to the HDS.
If there is no System Check result and it says the Immobilizer system is normal, try using Status Log. Check the possible failure of the Status Log with the highest count first, then the next highest, and so on.
Check the appropriate item on the screen to view the possible failures. Please note that the immobilizer control unit connector should not be disconnected before checking the Status Log, otherwise the counts will reset to zero.
If the Immobilizer system is normal, try using Status Log.
Check the possible failure of the Status Log with the highest count first, then the next highest, and so on.
Check the appropriate item on the screen to view the possible failures.
Please note that the immobilizer control unit connector should not be disconnected before
checking the Status Log, otherwise the counts will reset to zero.

46. HDS with Keyless Access
If the vehicle has a keyless access system, it overrides the immobilizer system. You will need to start the vehicle using the key in the ignition to access the Immobilizer Test Mode menu.

47. Diagnosis Using PID data
Common Problems (Using PID data)
On vehicles where System Check and Status Log are not available, you will have to use the Engine Data List on the HDS and monitor the IMMOBI STATUS at the time of failure. It will display one of two conditions when trying to start the engine, either RUN or BAN.
If RUN is displayed, the Immobilizer system is OK and normal troubleshooting for the fuel and ignition systems is advised.
If BAN is displayed, the Immobilizer system is at fault. Try using another programmed key to see if the vehicle starts. If it starts, the first key is faulty or not programmed into the system. If the engine still does not start with another programmed key, troubleshoot the immobilizer system starting with the operation of the immobilizer system indicator, checking pinfits, opens and shorts, power and ground, and then replacing the immobilizer control unit-receiver with a known-good one.

48. BAN indicates immobilizer fault

49. HDS need for replacing parts
Replacement Info (except Type 2)
On all systems, but Type 2, when replacing the ECM/PCM, the immobilizer control unit, or the IMOES unit, you must use the HDS to instruct the new ECM/PCM, immobilizer control unit, or IMOES unit to recognize the other's unique serial code or the engine will not start.

50. Early Type 2 requires all keys for PCM programming
Replacement Info Type 2
If you replace the ECM/PCM on early Type 2 systems, you must have all the programmed keys before rewriting the new ECM/PCM with the HDS to accept the transponder codes sent from the receiver, or the engine will not start.
On later Type 2 systems, the ECM/PCM was enhanced so that you only need to have one programmed key before rewriting the new ECM/PCM.

51. If lamp on with engine running it is a free start
ECM/PCM Free Starts
After replacing the ECM/PCM, program all of the keys into the system before giving the vehicle back to the customer.
If the keys cannot be programmed into the system, but the engine starts with any key, check the immobilizer indicator. If the indicator is ON while the engine is running, the ECM/PCM contains free starts which must be consumed before keys can be programmed to the new ECM/PCM. To consume the free starts, start and stop the engine until the indicator starts to flash when starting the engine.