Engine Immobilizer: Overview Lexus IS I

DESCRIPTION & OPERATION

The engine immobilizer system is a theft prevention system. When you insert the key in the ignition switch, the transponder chip in the key's head transmits an electronic code to the vehicle. The engine will start, only when the electronic code in the chip corresponds to the registered ID code for the vehicle.

The system is automatically set when the key is removed from the ignition switch. At this time, the security indicator light flashes. When you insert the key in the ignition switch, the security indicator light goes out and the system is canceled automatically, which enables the engine to start.

SYSTEM OPERATION CHECK

1. Trouble shooting of a engine immobilizer system complaint begins with verification of the customer problem. If problem occurs, go to step 3 . If problem does not occur, go to next step.
2. If problem does not occur, review conditions under which problem occurred for customer and try to duplicate those conditions. For example, if the problem occurs on rainy days or during high humidity conditions, sprinkle water onto vehicle and see if malfunction occurs. DO NOT sprinkle water directly into engine compartment or onto electronic components. Visually inspect for signs of mechanical and electrical damage. Inspect for blown fuses and damaged relays. Inspect for loose or corroded connections, damaged wiring harnesses and/or switches. Check for a broken or partially broken wire inside insulation, which could cause system malfunction but prove good in a continuity/voltage check with system disconnected. Ensure any aftermarket electronic equipment is properly installed. If fault is found, repair as necessary.
3. Preform pre-check. See «PRE-CHECK»(ref-154848-S16450899302003052900000) under SELF-DIAGNOSTIC SYSTEM. Check a DTC and note if a code is output. Delete the DTC. Check if the DTC will be output once again, when the problem symptom is simulated based on the noted code. When a normal code is output, go to «PROBLEM SYMPTOM INDEX»(ref-154848-S06742752652003052900000) table. When a malfunction code is output, go to «DIAGNOSTIC TROUBLE CODE INDEX»(ref-154848-S13693371392003052800000) table. PROBLEM SYMPTOM INDEX Symptom Suspected Area (1) Immobilizer Is Not Set (Engine Starts With Key Codes Other Than The Registered Key Code) (2) Engine Does Not Start (3) (4) (5) (6) (2) Security Indicator Is Always ON (7) (4) (2) Security Indicator Is Always ON (Although Code Has Been Registered In The Automatic Registration Mode, Indicator Is Not OFF) (4) (5) (6) (2) Security Indicator Is OFF (When DTC Of Immobilizer Is Output) (4) (5) (6) (2) Security Indicator Is OFF (When DTC Of Immobilizer Is Not Output) (4) (2) Security Indicator Is Abnormally Blinking (4) (2) (1) Perform test procedures in order listed under suspected area. (2) Check the ECM. (3) Check that the key which did not start the engine has been registered and that it is possible to start with other already registered key. (4) Check the wire harness. (5) Check the transponder key coil. See «TRANSPONDER KEY COIL CIRCUIT»(ref-154848-S15858268442003052900000) under CIRCUIT TESTS. (6) Check the amplifier. (7) Check the security indicator. Finish the automatic registration mode because the mode might still remain.
4. Inspect the circuit and parts. See «DIAGNOSTIC TESTS»(ref-154848-S11589074902003052800000) and «CIRCUIT TESTS»(ref-154848-S42919607292003052900000) .
5. After repairs have been completed, confirm that problem has been eliminated. Operate system under same conditions recorded for original complaint. If problem is no longer present and no DTCs are present, repair has corrected problem. If problem is still present or DTCs are reset, further diagnosis and repair is required.