Control Unit

The Single Board Engine Controller (SBEC) is a digital computer that controls air/fuel ratio, canister purge, charging system, cooling fan, emission control devices, fuel injector pulse width, idle speed, ignition coil dwell, spark advance, turbocharger wastegate (Turbo I) and turbocharger vane position (Turbo IV).

The SBEC has a voltage converter that converts battery voltage to a regulated 5 volts and 8 volts output. The 5 volts is used to power Manifold Absolute Pressure (MAP) sensor, Throttle Position Sensor (TPS) and logic circuits on all engines except 3.3L V6. On 3.3L, 5 volts is used to power MAP and TPS only. The regulated 8 volts is used to power distributor on all engines except 3.3L. On 3.3L 8 volts is used to power cam and crankshaft sensors.

NOTE: For ease of understanding, components are grouped into 2 categories. The first category, INPUT DEVICES, are components which control or produce voltage signals that are monitored by the ECU. The second category, OUTPUT SIGNALS, are components that are controlled by the ECU (this is usually accomplished by the ECU grounding individual circuits).