Grand Caravan L4-153 2.5L SOHC VIN K TBI (1988)
Engine Control Module: Description and Operation
General Operation
Fig. 2 Single Module Engine Controller (SMEC)
The SMEC, Fig. 2, is mounted in the engine compartment and contains circuits necessary to energize the ignition coil, fuel injectors and alternator
field in order to minimize electrical noise in the passenger compartment. The SMEC contains a voltage converter which converts battery voltage into a
regulated 8 volt output to energize the ignition pick up coil. The externally mounted Automatic Shut Down (ASD) relay which interrupts power to the
fuel pump, ignition coil and injector when necessary is controlled by the SMEC.
The ASD relay is turned on and off by the SMEC in response to distributor reference pulses. When distributor reference pulses are transmitted to the
SMEC, the SMEC activates the ASD relay. However, when no reference pulse is transmitted to the SMEC, the ASD relay is deactivated and power is
shut off to the fuel control system and ignition coil.
If a problem is sensed by the SMEC often enough to be considered a malfunction, it is stored in the SMEC memory in the form of a fault code on
1987-88 models, and a fault message on 1989 models. If the problem is repaired, or ceases to occur, the SMEC will cancel the code or message after
20---40 engine cycles.
Fault codes can be called up and displayed either by observing flashes of the check engine lamp or by using diagnostic tool C-4805 on 1987 models
and the Diagnostic Readout Box II (DRB II) on 1988 models.
