Continental Automotive 5WK47631 User Manual

Siemens VDO Automotive AG SV C BC P2 RF TG

User Manual

of the

Siemens VDO

OPEL Immobiliser

type 5WK4 7631

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Siemens VDO Automotive AG SV C BC P2 RF TG

System description of the Opel Immobilizer 2nd Generation
Redesign

The immobilizer 2nd generation prevents drive away car theft powered by its
own engine without having a valid key. It uses an inductive data transmission
between transponder (mounted inside the key) and the control unit. This data
link is working with a carrier frequency of 125 kHz and uses amplitude
modulation for transmitting data to the transponder. For the direction from the
transponder to the control unit damping modulation with pulse duration coding
is used.

Functional description
After switching on the ignition the immobilizer transmits a random number to

the transponder. It calculates a result and transmits it back to the immobilizer.
The result is checked and if it is correct, the engine will be released. After that,
the immobilizer is switched off until another start is attempted. The longest
period for transmitting 125 kHz is 3 seconds.

Typical usage pattern (for Europe only)

15 operations in 24 hours with a transmission duration of 2 seconds.
→ total transmission duration of 1.25 seconds within 1 hour

Transmitter ON 1.25 seconds / hour
Transmitter OFF 3598.75 seconds / hour

Duty Cycle: TON / T

(ON+OFF)

x 100% = 1.25 / 3,600 x 100 % = 0.03 %

Technical Data

Carrier frequency: 125 kHz ± 5kHz
Field strength: < 40 dBµA/m @ 10m
Type of modulation ASK
Number of channels: 1
Power supply: 12 V DC
Type of battery: car battery
Transmission range: 20 cm

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