Circuit Description

How the Circuit Works

The immobilizer system prevents the engine from starting by disabling the fuel system unless the proper keyless remote or key is used. The immobilizer system consists of the following:
- Immobilizer-keyless control unit
- Keyless remote
- Transponder in the key
- MICU (in the under-dash fuse/relay box)
- PCM

Power Supply

Fuse 7 (in the under-dash fuse/relay box) supplies battery voltage at all times to the immobilizer-keyless control unit, gauge control module, and MICU (in the under-dash fuse/relay box).

When the ignition switch is in the ON (II) or START (III) position, fuse 19 (in the under-dash fuse/relay box) supplies battery voltage to the PCM and the immobilizer-keyless control unit.

Operation

Inserting the key in the ignition switch and turning to the ON (II) position causes the immobilizer-keyless control unit to send power to the transponder in the built-in key. The transponder sends a coded signal back to the immobilizer-keyless control unit, which then sends a coded signal to the PCM and MICU (in the under-dash fuse/relay box). The PCM and the MICU verify this coded signal, and the PCM signals the fuel pump control unit to operate the fuel pump.

When using the keyless remote, it sends a signal to the immobilizer-keyless control unit-receiver. The immobilizer-keyless control unit sends a coded signal to the MICU. The MICU verifies that the correct code is used, and if so, it signals the PCM. The PCM then signals the fuel pump control unit to operate the fuel pump.