4FB1 I-Mark Component Location: the controller unit is located beneath the glove compartment. The glow plug relay unit is located in the relay box at the right side of the engine compartment. The dropping resistor is located near the fuel inlet pipe of the engine. The glow plugs and sensing resistor is located on the right side of the engine installed in the cylinder head. The fusible link is located near the battery and relay box at the left side of the engine compartment. The thermo switch is located in the thermostat housing of the engine.
Dropping resistor check: check for continuity across the terminals. If no continuity exists, replace the unit.
Thermo switch check: submerge the end of the switch in water and raise the temperature gradually. The switch should be OFF between 126 and 19140and#x00B0;F (53 and 1960and#x00B0;C) or lower. The switch should be ON between 134 and 19145and#x00B0;F (57 and 1963and#x00B0;C) or higher. If not, replace the switch.
The glow plugs are located under the injection nozzles.
- Disconnect the negative battery cable.
- Disconnect the dropping resistor for the I-Mark.
- Disconnect the glow plug and remove from the engine. The plug is threaded into the cylinder head.
- Lubricate with anti-seize compound before installing the plug.
- Install and torque the plug to 65 ft. lbs. (88 Nm).
- Reconnect the plug and dropping resistor.
- Connect the battery cable and check operation.