SYSTEM DESCRIPTION ENGINE IMMOBILISER SYSTEM DESCRIPTION The engine immobiliser system is designed to prevent the vehicle from being stolen. This system uses the transponder key ECU assembly that stores the key ID codes of authorized ignition keys. If an attempt is made to start the engine using an unauthorized key, the transponder key ECU assembly sends a signal to the ECM to prohibit fuel delivery and ignition, effectively disabling the engine. FUNCTION OF MAIN COMPONENTS
SYSTEM FUNCTION (a) When the transponder key ECU assembly detects that the unlock warning switch assembly is on, the transponder key ECU assembly applies current to the transponder key coil and produces a magnetic field around the antenna coil. A transponder chip in the key grip outputs a key ID code signal using electromotive force generated by the magnetic field. The transponder key coil receives the signal and sends it to the transponder key ECU assembly. The transponder key ECU assembly checks if the key ID code received from the transponder key coil matches the registered key ID code. When the engine is started, the ECM communicates with the transponder key ECU assembly and checks the key verification result. In addition, the ECM checks if the engine ID codes stored in the transponder key ECU assembly and ECM match. If they do not match, the ECM prohibits engine start. |
Toyota Tundra Service Manual > Audio And Visual System: Vehicle Speed Signal Circuit between Radio Receiver and Combination Meter
DESCRIPTION Audio function: This circuit is necessary for the automatic sound levelizer (ASL) built into the radio and display receiver assembly. ASL function: Speed signals are received from the combination meter assembly and used for the ASL. The ASL function automatically adjusts the sound volume ...
