This Chilton 68680 DIY repair and service manual, covers 1998-2010 Toyota Sienna minivans, which are available as four- or five-door vans. All models feature a sliding side door on the right side, while five-door models have an additional sliding door on the left side.

Power comes from a transversely-mounted V6 engine, equipped with electronic port fuel injection. The engine drives the front wheels through a four-speed automatic transaxle via independent driveaxles.

CYLINDER HEADS | REMOVAL AND INSTALLATION WARNING: Wait until the engine is completely cool before beginning this procedure. REMOVAL (Refer to illustrations 11.7, 11.8 and 11.11)

1. Disconnect the negative cable from the battery.
2. Drain the cooling system, including the block (see Chapter 1).
3. Remove air intake plenum and intake manifold (see Section 6).
4. Remove the exhaust manifold(s) (see Section 7).
5. Remove the alternator (see Chapter 5).
6. Remove the timing belt, camshaft sprockets and upper idler pulley (see Section 8).
NOTE: If the timing belt is not being replaced at the time the heads are removed, the timing belt and lower timing belt cover don't have to be completely removed. Follow the Steps in Section 8, marking the belt location at the lower cover at TDC, and removing the belt only from the camshaft sprockets and idler pulley.
7. Remove the bolts holding the number 3 timing belt cover (see illustration).
8. Disconnect the coolant sensor connectors and remove the water transfer casting (see illustration).
9. Remove the camshaft(s) from the head(s) you intend to remove (see Section 10).
10. Remove the bolts at the rear of the cylinder heads and move the engine wiring harnesses away form the heads.
11. Using an 8 mm hex bit or Allen wrench, remove the recessed head bolts (one in each head) (see illustration).
12. Using a 12-point socket, loosen the rest of the cylinder head bolts in 1/4-turn increments until they can be removed by hand. Follow the reverse order of the recommended tightening sequence (see illustration 11.23).
13. Lift the cylinder head off the engine block. If the head is stuck, place a wood block against it and strike the wood with a hammer.

FUEL PUMP ELECTRICAL CIRCUIT CHECK
(Refer to illustrations 3.8 and 3.9)

8. If the pump does not turn on (makes no sound) with the ignition switch in the ON position, check the IGN fuse and the EFI fuse located in the engine compartment fuse center. If either fuse is blown, replace the fuse and see if the pump works (see illustration). If the pump now works, check for a short in the circuit between the fuel pump relay (circuit opening relay) and the fuel pump.
9. If the pump still does not work, remove the EFI main relay and check for battery voltage at the relay connector. One of the terminals should have battery voltage available at all times and another terminal should have battery voltage available with the ignition key On. If battery voltage does not exist, check the circuit from the fuse/relay box to the battery or ignition switch. If battery voltage exists at the relay socket, check the relays.
NOTE: These models are equipped with an EFI main relay (see illustration 3.8) and a fuel pump relay (circuit opening relay), all located in the engine compartment fuse/relay box(es) (see illustration).
10. If the relays are good and the fuel pump does not operate, check for power to the fuel pump at the fuel pump electrical connector. Also check for continuity to chassis ground at the connector. If voltage is present at the fuel pump connector, the ground circuit is good and the fuel pump does not operate when connected, replace the fuel pump.