Note. For information on engine immobilizer system, see COMPUTERIZED ENGINE CONTROLS in THEORY & OPERATION article.
| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM harness connector and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. If ECM is replaced, ECM must be programmed with proper ignition key code for engine immobilizer system. For programming procedures, see COMPUTER RELEARN PROCEDURES - LEXUS article. |
Circuit Description
If this DTC is stored, the ECM shuts down the power for the throttle motor, and the throttle valve is fully closed by the return spring and locked at a certain opening angle. Also, the whole electronically controlled throttle operation is cancelled until the system returns to normal and the ignition switch is turned off. Possible causes are open in ETCS power source circuit and ECM. (Scheme 175)
Scheme 175
Diagnostic Aids
Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.
Scheme 176
Scheme 177
Scheme 178
- Remove ETCS fuse from the engine room No.1 relay block. (Scheme 176) Check continuity of fuse and replace as necessary. If fuse is okay, go to next step.
- Check the voltage between terminal E1 of ECM E3 connector and +BM of ECM E6 connector. (Scheme 177) If 9-14 volts are present, check and replace ECM. If 9-14 volts are not present, go to next step.
- Remove the ETCS fuse from the engine room No. 1 relay block. (Scheme 176) Disconnect the ECM E6 connector. (Scheme 178) Check continuity between the wire harness side connectors. Continuity should be present between ETCS fuse terminal 2 of relay block and +BM (V11-2). Continuity should not be present between ETCS fuse terminal No. 2 of relay block or +BM (V11-2) and ECM E3 connector terminal E1.
- Disconnect battery positive terminal. Check continuity between wire harness side connectors. Continuity should be present between battery positive terminal and ETCS fuse terminal No. 1 of relay block. Continuity should not be present between battery positive terminal or ETCS fuse terminal No. 1 of relay block and ECM E3 connector terminal E1. If okay, replace ECM. If not okay, repair or replace harness or connector.