Computers and Control Systems: Application and ID

There are major differences in the two (2) fuel injection systems used on this vehicle, be sure you know which system you have before any work begins. Vehicles equipped with CALIFORNIA EMISSIONS have a significantly different fuel system than vehicles equipped with FEDERAL EMISSIONS. Because of this, the need to positively identify the vehicle's fuel system before work begins is very important. Adding confusion to the problem is the fact that, the engine I.D. code can not be used to properly identify the fuel system, (the engine I.D. code was used for fuel system I.D. in the past). The two different systems can be found on engines which have the same I.D. code, the systems look alike, but they are very different in terms of total system operation. Several testing and adjustment procedures are completely different as well. These two systems are DIGIFANT I (CALIFORNIA) and DIGIFANT II (FEDERAL). The two systems do share many components which are identical, but they also have components which are only compatible with the system for which they were designed.

The biggest difference in these two systems is that all CALIFORNIA vehicles, (DIGIFANT I) have an ON BOARD DIAGNOSIS (OBD) system as required by the California Air Resources Board. The OBD system is incorporated into the DIGIFANT I control unit (ECU). The OBD system is designed to detect malfunctions in the fuel metering system which may cause the vehicle to fail an exhaust emission test. If the OBD system detects a fault within the fuel system, it illuminates a dash warning light informing the driver that a malfunction has developed. The Digifant I control unit (ECU) has permanent fault memory capability which will receive and store the malfunction information as fault codes. The fault codes can be recalled from the ECU then used for diagnosing the malfunction, refer to DIAGNOSIS AND TESTING PROCEDURES for more information. The FEDERAL vehicles, (DIGIFANT II) do not have ON BOARD DIAGNOSIS.

The first step to accurately identify which injection system is on a particular vehicle is to check the underhood emissions label which will state if the vehicle is either a CALIFORNIA vehicle or a FEDERAL vehicle. However if the emissions label is missing, trying to identify which system you have can be tricky and time consuming because they look so much alike. This can be simplified if you know which components are different between the two systems, what these components look like, and which component is used by each system. This section will give you information on which components are different, what the components look like, where they are located and which component is used by each system. This should help you to quickly and accurately determine if the vehicle is a CALIFORNIA vehicle or a FEDERAL vehicle and which procedures are needed to test and repair the fuel system.

THE SYSTEMS

Digifant Engine Management System:

DIGIFANT I CALIFORNIA EMISSIONS

Digifant II Engine Management System:

DIGIFANT II FEDERAL EMISSIONS

Fuel System I.D. By Component Application:

DIGIFANT I & II COMPONENT APPLICATION AND I.D. CHART

THE KEY COMPONENTS

IGNITION COIL AND IGNITION COIL WITH POWER STAGE
One of the easiest and fastest ways to identify DIGIFANT I from DIGIFANT II is the ignition coil, the coil is mounted at the rear of the engine compartment on the firewall. Coil placement is next to the battery near the center of the firewall. If needed trace the coil wire from the center position of the distributor to the coil on the firewall.

Ignition Coil With Power Stage:

DIGIFANT I (CALIFORNIA), uses a new type coil known as an ignition coil with power stage. The new coil with power stage looks basically square with a round half circle protrusion on one end. The coil wire terminal is located on side of this round section, a three wire harness connector is attached to the same side near the base, and at the center on the same side is two small wire terminal studs.

Digifant II Coil:

DIGIFANT II (FEDERAL), uses the same conventional type coil that has been used for many years although it is an electronic version it still looks the same, approximately 6 inches long, a round cylindrical shape with the coil wire terminal in the center top of the coil and two small wire terminal studs as well.

THROTTLE VALVE SWITCH AND THROTTLE VALVE POTENTIOMETER
The throttle valve switch and throttle valve potentiometer are located on the throttle body of the engine at the air inlet of the intake manifold. If needed trace the throttle cable to the throttle body, the switch or potentiometer will be mounted on the bottom side of the throttle body.

Digifant I Throttle Valve Potentiometer:

DIGIFANT I (CALIFORNIA), uses a throttle valve potentiometer, the potentiometer not only informs the ECU when the throttle is in the idle position but every position from idle to full throttle is monitored. The throttle valve potentiometer has a harness connector attached that contains THREE wires.

Digifant Throttle Valve Switch:

DIGIFANT II (FEDERAL), uses a throttle valve switch, this simple ON/OFF switch informs the ECU when the throttle is in the idle position. The throttle valve switch has a harness connector attached that contains TWO wires.

Digifant Fuel Rail:

FUEL INJECTOR MAIN HARNESS CONNECTOR
The fuel injectors are located along the intake side of the engine, the injectors are all attached to a common fuel rail which supplies them fuel. The fuel injectors are also supplied electrical current to operate from a common harness connector, this connector is located at one end of the fuel rail.

Digifant I Injector Harness Connector:

DIGIFANT I (CALIFORNIA), uses an injector main harness connector that contains FIVE wires.

Fuel Injector Main Harness Connector 2 Wire:

DIGIFANT II (FEDERAL), uses an injector main harness connector that contains TWO wires.

Digifant Control Unit Location:

DIGIFANT I & II ELECTRONIC CONTROL UNIT (ECU)
The DIGIFANT ECU is located under the dash on the right side by the glove box.

Digifant I 38 Pin Control Unit Connector:

DIGIFANT I (CALIFORNIA), uses a control unit that has a 38 PIN harness connector.

Digifant II 25 Pin Control Unit Connector:

DIGIFANT II (FEDERAL), uses a control unit that has a 25 PIN harness connector.