TESTING

2TZ-FE Engine

1. Disconnect the IAC valve wiring.
2. Using an ohmmeter, measure the resistance between terminals +B and the other terminals (ISC1 and ISC2 or ISCC and ISSC, depending on the year of the van).

   Fig. 1: Use an ohmmeter to measure the resistance between the terminals of the IAC valve — ISC1 and ISC2 type

   Fig. 2: Use an ohmmeter to measure the resistance between the terminals of the IAC valve — 2TZ-FE engine — ISCC and ISSC type

3. Resistance should be between 18.8–22.8 ohms.
4. If the resistance is not within specifications, replace the IAC valve.
5. To check the operation of the IAC valve, the engine should be at normal operating temperature and the transmission in Neutral.
6. Using a jumper wire, connect terminals TE1 and E1 of the DLC1.

   Fig. 3: A jumper wire is placed on these two terminals of the DLC1 to test the IAC valve operation — ISC1 and ISC2 type

   Fig. 4: A jumper wire is placed on these two terminals of the DLC1 to test the IAC valve operation — ISCC and ISSC type

7. After the engine rpm is kept at 1000–1200 for about 5 seconds, check that the rpm drops about 200 rpm.
8. If the rpm operation is not as specified, check the IAC valve, wiring and engine ECM.
9. Remove the jumper wire form the DLC1.

2TZ-FZE Engine

1. Disconnect the IAC valve wiring.
2. Using an ohmmeter, measure the resistance between terminals +B and the other terminals RSC and RSO.

   Fig. 5: Use an ohmmeter to measure the resistance between the terminals of the IAC valve — 2TZ-FZE engine

3. Resistance should be between 17.0–24.5 ohms cold and 21.5–28.5 ohms hot.
4. If the resistance is not within specifications, replace the IAC valve.
5. To check the operation of the IAC valve, the engine should be at normal operating temperature and the transmission in Neutral.
6. Using a jumper wire, connect terminals TE1 and E1 of the DLC1.
7. After the engine rpm is kept at 1000–1200 for about 5 seconds, check that the rpm drops about 200 rpm.
8. If the rpm operation is not as specified, check the IAC valve, wiring and engine ECM.
9. Remove the jumper wire form the DLC1.