System Testing

Fig. 39 Throttle position adjustment specifications:

4A-C & 4A-LC ENGINES COROLLA FRONT WHEEL DRIVE

1. Start engine and run until it reaches normal operating temperature.
2. Ensure that all electrical accessories are off and that idle speed is within specifications.
3. Disconnect hose from TVSV port ``M'' to disable EGR system, then plug valve port.
4. Disconnect vacuum hose from TP outer port. Actuator should extend to first step and engine should run at specified ``idle-up'' speed, Fig. 39.
5. Reconnect hose to outer port and disconnect hose from TP inner port. Actuator should extend to second step and engine should run at specified TP set speed, Fig. 39.
6. If actuator does not extend properly, or if speeds are not within specifications, adjust or replace throttle positioner.
7. Reconnect vacuum hose to TP inner port. If engine does not return to idle within 2-6 seconds, VTV is defective.
8. Turn on all electrical accessories while observing TP actuator. Actuator should extend to first step.
9. If actuator does not extend, disconnect electrical connector from VSV and apply battery voltage to VSV terminals.
10. If actuator extends to first step, check feed circuit to VSV. If actuator does not extend, VSV is defective.