Kia Cee'd Quiz
Body Electrical System

Description and Operation

In this manual: Body Electrical System
General Information — 15Maintenance — 7Engine Mechanical System — 84Engine Electrical System — 49Emission Control System — 22Fuel System — 95Clutch System — 28Manual Transmission — 21Dual Clutch Transmission (DCT) System — 47Drive Shaft and Axle — 20Suspension System — 36Steering — 23Restraints — 39Brake System — 54Body (Interior and Exterior) — 209Body Electrical System — 254Heating, Ventilation, and Air Conditioning — 56
2steps
~12min
1/5difficulty
Done 0 of 2

Description

The immobilizer system disables the vehicle if the correct ignition key is not used. In addition to existing anti-theft systems such as car alarms, the immobilizer system is designed to sharply reduce vehicle theft.
  1. Transponder (TP) – Communication with IMMO ECU
    TP Read Protocol
    1. After IGN is turned on (or CPU reset is released), the IMMO_ECU sends a challenge to the TP and verifies the serial number and signature.
    2. When the response from the input transponder is incorrect, the input is retried.
    3. When the response from the input transponder is correct, the data is calculated by the encryption operation in the EEPROM program and compared with the data received from the TP. When the codes match, input is complete. If the codes do not match, input continues until the codes are the same.
    4. If the IMMO_ECU EEPROM is not programmed when the correct transponder is entered (CRC Check OK), the entry is complete.
    5. After IGN1 is switched on (CPU reset is released), the IMMO_ECU reads the transponder code up to 5 times.
    6. In the IGN1 ON and EMS_state=Lock condition, when an ACKNOWLEDGE is received, the TP performs re-authentication.
  2. Transponder / IMMO ECU / EMS Authentication

Components and Operation

PCM (Powertrain Control Module)
  1. The PCM (ECM) (A) checks the ignition key using a special encryption algorithm that is also programmed into the transponder and the PCM (ECM) simultaneously. Only if the results match can the engine be started. Data for all transponders that are valid for the vehicle is stored in the PCM (ECM). The ERN (Encrypted Random Number) value between the EMS and the encrypted Smartra device is verified, and the EMS determines the validity of the coded key.
ENCRYPTED IMMOBILIZER (A): The IMMOBILIZER communicates with the transponder built into the ignition key. This wireless communication operates at a radio frequency (125 kHz). The IMMOBILIZER is installed behind the protective cover near the center crossmember. The radio frequency signal from the transponder, received by the antenna coil, is converted into serial communication messages by the IMMOBILIZER. Messages received from the PCM (ECM) are converted into a radio frequency signal, which is transmitted to the transponder through the antenna. The IMMOBILIZER does not perform transponder validity checks or encryption algorithm calculations. This device is only an extended interface that converts the transponder's RF data stream into serial communication to the PCM (ECM) and vice versa.
Transponder (built-in key): The transponder has an advanced encryption algorithm. During the basic learning procedure, the transponder is programmed with vehicle-specific data. Vehicle-specific data is written to the transponder memory. The writing procedure is performed only once; therefore the contents of the transponder can never be changed or modified.

[Master Folding Key]

[Master Key Assistant]

Antenna Coil: The antenna coil (A) performs the following functions.
  • The antenna coil supplies power to the transponder.
  • The antenna coil receives the signal from the transponder.
  • The antenna coil sends the transponder signal to the IMMOBILIZER. It is located directly in front of the steering column lock.

Test yourself

A quick Kia Cee'd quiz: every answer comes with an explanation and a link to the manual page.