This started life as an idea on a
Ford owners
forum. OBD-II code readers which have a full set
of features and run from a laptop are now quite
common but the technology which bought about this
revolution is often forgotten. EEC-IV was Ford's
first sophisticated computerized engine management
system, designed so that a Ford technician could
interrogate the car's ECU and read faults and clear
fault codes. Fault codes (DTCs) are output using a
pulse system and are then read by the unit and
converted into legible text on the LCD. Ford
dealerships would have been equipped with a full
suite of equipment to interact with the car and read
this data, but this equipment is rare now and hugely
expensive.
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Prototype installed in
case |
The unit was built around a pre-programmed
PIC chip, both the PIC and circuit schematic were designed
by a Granada Mk3 owner (see
www.graynada.com). The
reader was adapted to work on the later Scorpio and built
into a case. A small production run of 12 units was built, I
built the first as a prototype and used it as reference for
the other 11. The circuit was built on strip board to keep
costs down, all components except for the PIC and the OBD
plug were easily available and were bought from Maplin
electronics.
The circuit was relatively simple - powered
by a 9v PP3 battery, the PIC being fed by a 7805 5v
regulator. Power and test functions controlled by
subminiature toggle switches, the only other components
needed were a 6MHz crystal, handful of diodes and a
transistor and a few capacitors and resistors. A small
trimmer pot was also added to adjust contrast on the LCD.
Finally an RS232 socket was added to enable data output to a
PC.
The units were then assembled in stages with
the cases being cut on a makeshift jig - I cut them with a
high speed milling cutter, using the jig which I had made as
a guide to get them all uniform. The front panels were made
in a CAD program and then printed on a regular printer and
laminated and cut to fit.
The readers were then finished and tested
individually.
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First nine
boards completed - waiting for displays, wiring and
cases |
First nine
FCR units completed |
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Prototype
powered up and working |
Close-up of one
of the completed units |
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