We have heard a lot of customer complaints about the built in immobilizer on the 2005 – 2006 Toyota Corolla, being the most common ones “The car cranks OK, but won’t start” or “The car cranks and starts, but the engine die in about a second and a half”.
Well, the above is most of the times caused by a mismatch of the engine immobilizer or a malfunctioning of its circuit (very rare).
What is it?
The immobilizer is an anti-theft measure, implemented on many modern cars today.
The system is integrated by (1) a special circuit in the ecu, (2) the car key, called “transponder key”, and (3) a coil antenna mounted around and inside the key lock assembly and (4)¬†the transponder circuit, where the antenna connects.
Inside your car¬†key, in the black or grey plastic part, there is a micro chip in a glass capsule, which contains the whole circuit needed for the key to transmit an unique code when close to the energized coil antenna. That is why your car key’s¬†plastic part is wider than normal, to accommodate the device.
The circuit inside the key needs no battery, as it is powered up by magnetic signals out coming from the coil antenna. Right after the key is energized by the antenna, it starts emitting back to the coil, the code it has previously stored. All the communication and power feeding between the car key and the transponder circuit installed inside the steering column, is electro-magnetical. The code that the car¬†key has programmed inside, is the code given to it when it was programmed by the dealer, using part of the VIN number.
The code received by the coil antenna from the car key, is amplified and decoded by the transponder circuit and then transmitted to the ecu to be compared with the code already¬†stored on it and then be sent back to the transponder for comparisons.
If the comparison tests Ok, then the transponder circuit sends a signal to the ecu to allow the engine to run. If on the other hand, the code is not recognized (mismatched), the ecu shuts off the engine a second and a half after starting it and flash the security indicator on the dash board.
Why this happens?
Well, this can be caused by several reasons. Some are the following:
1 – The owner lost a key, ordered a new one, but since the code is unique to every key, it won’t match the one on the ecu and will fail the comparison test, shutting the engine down.¬†On this state, the car should run with the valet parking key or any other valid copy of the key¬†the owner may have. The problem is if the lost key was the only one available.
2 – The owner needed an ecu replacement for any reason and the same will happen here, the code in the ecu won’t match the one on the key, shutting down the engine.
3 – A sudden malfunction of the system caused by an unexplainable reason like a power failure or by connecting an incompatible, wrong or faulty scanner or diagnostic equipment or anything alike.
What to do?
We have, as told by the dealer,¬†3 options here.
1 – Go to the dealer so they cut a new key and synchronize it (program it) with the existing ecu. The ecu must be in a state that can accept new keys. All ecru’s are supposed to have a capacity of accepting from 8 to 10 new keys (maybe around $100).
2 – If the dealer has the equipment, the ecu must be re-seeded so it can accept new keys, in case number one above doesn’t work (even more $$$).
3- Replace the ecu for a new one if the above two options don’t work and possibly¬†will need to buy new blank¬†keys. (probably from $800 to $1300).
yes, it is too pricey, but there is a third option not offered by the dealers, probably because they don’t know it. The ecu can be reflashed (reprogrammed) so it will be ready to accept either new or old keys. This procedure will put the ecu key memory in a virgin state,¬†as a new one. The downside of this is that a special reprogramming equipment and software is needed, but we¬†have tested it and works¬†perfect and only takes a few minutes. Another downside is that the ecu must be sent by mail so the job get done.
What is done to the ecu? It is reprogrammed (only the part that works with the key codes) without removing any part from the circuit. The job is completely untraceable and warrantied to work 100%.
This service can be found at the link below:
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