Throttle Full Close Switch: Testing and Inspection

Fig. 2 Diagnostic connector terminal identification:

Fig. 3 ECU connector terminal identification:

It is important that all testing be performed with ISC plunger in fully extended position, as it should be when engine is off. If it is necessary to extend plunger, ISC is probably defective. Test ISC and replace if necessary.

1. Turn ignition switch on and connect voltmeter between D2-7 and D2-13, Fig. 2. Voltage should read close to zero at closed throttle and above two volts off closed throttle position.
2. If voltage is always zero, check for short circuit to ground in harness or switch. Test for open circuit between ECU terminal J2-20 and switch, Fig. 3.
3. If voltage is always more than two volts, check for open circuit between ECU and switch connector or between switch connector and ground.
4. Repair or replace wiring as necessary.