Engine Immobilizer: Overview Scion tC I рестайлинг

SYSTEM DESCRIPTION

1. ENGINE IMMOBILIZER SYSTEM DESCRIPTION The engine immobilizer system is designed to prevent the vehicle from being stolen. This system uses a transponder key ECU that stores the key codes of authorized ignition keys. If an attempt is made to start the engine using an unauthorized key, the ECU sends a signal to the ECM to prohibit fuel delivery and ignition, effectively disabling the engine. When the ECU detects that the unlock warning switch is ON, the ECU provides current to the transponder key coil and produce a faint electric wave. A transponder chip in the key grip receives the faint electric wave. Upon receiving the faint electric wave, the transponder chip outputs a key ID codes signal. The transponder key coil receives this signal, the transponder key amplifies it, and then the signal is transmitted to the ECU. The ECU matches the key's ID code with the vehicle's ID code, which was previously registered in the ECU, and then communicates with the ECM using the SFI communication. After the identification results show that the key's ID code matches the vehicle's ID code and the ECU has confirmed their match: 1) the immobilizer system is canceled the engine and the engine starting systems (fuel injection control and ignition control) enter standby mode; and 2) the ECU turns off the security indicator light.

DESCRIPTION

This DTC will be output when the key is inserted into the ignition key cylinder, but the transponder key ECU does not detect the ON condition of the unlock warning switch. Normally, inserting the key into the ignition key cylinder turns ON the unlock warning switch, which is then detected by the ECU.

DTC DETECTION CONDITION AND TROUBLE AREA

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1. READ VALUE OF INTELLIGENT TESTER (UNLOCK WARNING SWITCH ASSEMBLY) Check the DATA LIST for proper functioning of the unlock warning switch. Transponder key ECU assembly DATA LIST Item Measurement Item / Display (Range) Normal Condition Diagnostic Note KEY SW Unlock warning switch signal / ON or OFF ON: Key is in ignition key cylinder OFF: No key is in ignition key cylinder - OK: ON (key is in ignition key cylinder) appears on the screen. OK: REPLACE TRANSPONDER KEY ECU ASSEMBLY NG: Go to next step
2. INSPECT UNLOCK WARNING SWITCH ASSEMBLY Remove the unlock warning switch. Measure the resistance of the switch. Standard resistance RESISTANCE SPECIFICATION Tester Connection Switch Condition Specified Condition 1 - 2 Pushed Below 1 ohms Not pushed 10 kohms or higher NG: REPLACE UNLOCK WARNING SWITCH ASSEMBLY OK: Go to next step
3. CHECK WIRE HARNESS (UNLOCK WARNING SWITCH - TRANSPONDER KEY ECU AND BODY GROUND) Disconnect the U1 switch connector. Disconnect the T8 ECU connector. Measure the resistance of the wire harness side connectors. Standard resistance RESISTANCE SPECIFICATION Tester Connection Specified Condition T8-10 (KSW) - U1-2 Below 1 ohms U1-1 - Body ground NG: REPAIR OR REPLACE HARNESS AND CONNECTOR OK: REPLACE TRANSPONDER KEY ECU ASSEMBLY

This DTC is detected when the transponder key coil is open or short circuited.

DTC DETECTION CONDITION AND TROUBLE AREA

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1. READ VALUE OF INTELLIGENT TESTER (TRANSPONDER KEY COIL) Check the DATA LIST for proper functioning of the transponder key coil. Transponder key ECU assembly DATA LIST Item Measurement Item / display (Range) Normal Condition Diagnostic Note ANTENNA COIL Transponder key coil condition / NORMAL or FAIL NORMAL: Antenna coil is normal FAIL: Antenna coil is malfunctioning - OK: NORMAL (transponder key coil is normal) appears on the screen. OK: REPLACE TRANSPONDER KEY ECU ASSEMBLY NG: Go to next step
2. CHECK WIRE HARNESS (TRANSPONDER KEY ECU ASSEMBLY - TRANSPONDER KEY AMPLIFIER) Disconnect the T8 ECU connector. Disconnect the T7 amplifier connector. Measure the resistance of the wire harness side connectors. Standard resistance RESISTANCE SPECIFICATION Tester Connection Specified Condition T8-8 (VC5) - T7-1 (VC5) Below 1 ohms T8-11 (CODE) - T7-4 (CODE) T8-12 (TXCT) - T7-5 (TXCT) T8-13 (AGND) - T7-7 (GND) T8-8 (VC5) or T7-1 (VC5) - Body ground 10 kohms or higher T8-11 (CODE) or T7-4 (CODE) - Body ground T8-12 (TXCT) or T7-5 (TXCT) - Body ground T8-13 (ANGD) or T7-7 (GND) - Ground ground NG: REPAIR OR REPLACE HARNESS AND CONNECTOR OK: REPLACE TRANSPONDER KEY AMPLIFIER

This DTC is output when: 1) during key code registration, a key malfunction occurs; 2) the key code was unable to be registered properly.

DTC DETECTION CONDITION AND TROUBLE AREA

This DTC is output when a key with an incomplete key code is inserted into the ignition key cylinder.

DTC DETECTION CONDITION AND TROUBLE AREA

This DTC is output when a key with a key code that has not been registered in the transponder key ECU is inserted into the ignition key cylinder.

DTC DETECTION CONDITION AND TROUBLE AREA

This DTC is output when a key that does not have a transponder chip is inserted into the ignition key cylinder or if communication between the key, transponder key amplifier and transponder key ECU is not possible.

DTC DETECTION CONDITION AND TROUBLE AREA

This DTC is output when a communication error occurs between the transponder key amplifier and transponder key ECU. A possible reason for the communication error is that noise is occurring on the communication line.

DTC DETECTION CONDITION AND TROUBLE AREA

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1. CHECK KEY Check if the ignition key being used is near other ignition keys, as shown in the illustration. Also, check if the key ring is in contact with the key grip. Result: RESULT REFERENCE Result Proceed to Key is near other keys and / or key ring is in contact with key grip A Key is not near other keys and / or key ring is not in contact with key grip B B: Go to step 3 A: Go to next step
2. CHECK FOR DTC Separate the keys from each other or remove the key ring. Delete the DTC (see «DTC CHECK/CLEAR»(ref-296241-S23002339592008082200000) ). Insert a key into the ignition key cylinder. Then remove it. Repeat for all the other keys. Check that no code is output. OK: END NG: Go to next step
3. CHECK TRANSPONDER KEY AMPLIFIER Using an oscilloscope or the intelligent tester, check for noise in the waveform between the terminals of the T7 amplifier connector and T8 ECU connector. OK: No noise is present (see illustration). TESTER CONNECTION AND SPECIFIED CONDITION Tester Connection Tool Setting Condition Specified Condition T8-11 (CODE) - T7-4 (CODE) 2 V/DIV., 20 msec./DIV. Ignition switch ON No noise is present NG: FIND CAUSE OF NOISE AND REMOVE IT OK: Go to next step
4. CHECK WIRE HARNESS (TRANSPONDER KEY ECU ASSEMBLY - TRANSPONDER KEY AMPLIFIER) Disconnect the T8 ECU connector. Disconnect the T7 amplifier connector. Measure the resistance of the wire harness side connectors. Standard resistance RESISTANCE SPECIFICATION Tester Connection Specified Condition T8-11 (CODE) - T7-4 (CODE) Below 1 ohms NG: REPAIR OR REPLACE HARNESS AND CONNECTOR OK: Go to next step
5. CHECK OPERATION OF TRANSPONDER KEY AMPLIFIER After replacing the transponder key amplifier with a normally functioning transponder key amplifier, check that the engine starts. OK: Engine starts. NG: REPLACE TRANSPONDER KEY ECU ASSEMBLY OK: END (TRANSPONDER KEY AMPLIFIER IS DEFECTIVE)

This DTC is output when one of the following occurs: 1) the ECM detects errors in its own communications with the transponder key ECU: 2) the ECM detects errors in the communication lines: or 3) the ECU communication ID between the transponder key ECU and ECM is different and an engine start is attempted.

DTC DETECTION CONDITION AND TROUBLE AREA

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This circuit provides power to operate the transponder key ECU.

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1. INSPECT FUSE (IG2, ECU-B, AM2, DCC) Remove the IG2 fuse from the instrument panel junction block. Remove the ECU-B, DCC and AM2 fuses from the engine room relay block. Measure the resistance of the fuses. Standard resistance: Below 1 ohms NG: REPLACE FUSE OK: Go to next step
2. CHECK WIRE HARNESS (TRANSPONDER KEY ECU ASSEMBLY - BATTERY AND BODY GROUND) Disconnect the T8 ECU connector. Measure the resistance and voltage of the wire harness and connector. Standard resistance RESISTANCE SPECIFICATION Tester Connection Specified Condition T8-14 (GND) - Body ground Below 1 ohms Standard voltage VOLTAGE SPECIFICATION Tester Connection Condition Specified Condition T8-2 (IG) - Body ground Ignition switch OFF Below 1 V Ignition switch ON 10 to 14 V T8-1 (+B) - Body ground Always NG: REPAIR OR REPLACE HARNESS AND CONNECTOR OK: REPLACE TRANSPONDER KEY ECU ASSEMBLY

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1. DISCONNECT CABLE FROM NEGATIVE BATTERY TERMINAL NOTE: Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to prevent airbag and seat belt pretensioner activation.
2. REMOVE STEERING COLUMN COVER Remove the 2 screws, steering column cover lower and steering column cover upper. HINT: Tilt the steering column assembly to the lowermost position when removing the steering column cover upper. Tilt it to the uppermost position when removing the steering column cover lower.
3. REMOVE UNLOCK WARNING SWITCH ASSEMBLY Disconnect the unlock warning switch connector from the ignition switch. Remove the unlock warning switch assembly by pushing up on the center part and disengaging the 2 claws. Manual transaxle: Remove the clamp from the steering column upper bracket assembly. Automatic transaxle: Disengage the secondary locking device. Automatic transaxle: Using a screwdriver, disengage the locking lug of terminals 3 and 4, and pull the terminals out from the unlock warning switch assembly connector rear side.

See also:
• SFI SYSTEM