Codes from the Engine ECU
1995 Mitsubishi FTO GPX
The FTO's engine ECU monitors everything
from sensors to injectors, solenoid valves to ignition. If it notices
a problem, it records this in the form of a diagnostic code. A Mitsubishi
dealer equipped with the right MUT-II diagnostic setup is apparently capable
of accessing these codes.
But what if no such service is available
to you? The FTO Workshop manuals do not provide any alternative method
for extracting diagnostic codes.
Fortunately, the EVO Workshop manuals
show a much easier way! Although the codes differ from the FTO, the method
of extraction is identical... and the whole process requires nothing more
than a single electrical lead...
Disclaimer: Do not attempt any wiring
modifications yourself without (a) checking the connections, wire colours,
etc. on your own vehicle, and (b) knowing what you are doing. I take no
responsibility for any cooked wiring, ECUs or anything else you may feel
like playing with. Any work done on your own vehicle is done so at your
The first step is
to remove the panel underneath the steering wheel. This simply requires
the removal of four screws. Note that the bonnet release cable and
lever will still be connected to this panel - just drop the panel
down and keep it out of the way.
Now if you crawl under there, you
will notice an interface socket on the left hand side, about level
with the bottom left screw you removed a moment ago. You can click
on the image (right) to enlarge...
This is the location of the diagnosis
connector, and I believe this is where a MUT-II unit is connected.
As I noted before, though, we don't
need a MUT-II to do our dirty work! The EVO manual states...
Earth No. 1 terminal (diagnostic control
terminal) of the diagnostic connector. Turn on the ignition switch.
The image to the
left was taken with the camera facing directly up. The "top" of
the picture is oriented to the rear of the vehicle. Incidentally,
the strange circular thing in the centre of the frame is simply
the alarm's glass breakage sensor.
As noted before, we must earth No.
1 terminal on this connector. The pin in question is the bottom
right one in the picture - highlighted.
All we have to do is ground out
this pin by using a single cable. With the engine ignition switch
on, the computer will flash the engine warning light to indicate
any stored diagnostic code(s).
Because it was a bit of a pain getting
in there and grounding this pin, I decided to find a less fiddly way of
triggering an error code output...
At the back of the
diagnostic plug, it was clear to see that the relevant pin was connected
to an easily accessible lead (grey with red stripe on my 1995 GPX,
but apparently a different colour on some other FTOs).
I used a standard patch connector
to attach an extra wire to the relevant lead (see image to right,
Now it is simply a matter of grounding
out the permanent diagnostic lead stowed under the dash.
When I get the chance, I will be
rewiring this with a push-button switch that will close the connection
from pin 1 to earth. Luxury...!
Here are the diagnostic codes, gleaned
both from the Workshop Manual and a few other places:
||Air Flow Sensor
||Intake air temperature sensor
||Throttle position sensor
||ISC Motor Position Sensor
||Engine coolant temperature sensor
||Crank angle sensor
||Camshaft position sensor
||Vehicle speed sensor
||BARO Sensor (listed as 26 in one info source)
||Ignition Timing Adjustment Signal
||Ignition coil and power transistor unit (Cylinder 1 & 4)
||Ignition coil and power transistor unit (Cylinder 2 & 5)
||Ignition coil and power transistor unit (Cylinder 3 & 6)
||Idle Air Control Valve/Servo Valve Position Sensor
||Communications wire with A/T-ECU
||Intake air control valve position sensor
||Alternator FR terminal
||Vacuum control solenoid valve (TCL)
||Ventilation control solenoid valve (TCL)
So what does an ECU diagnostic
code look like when it is displayed?
Well, it looks a lot like
This is blinking out diagnostic
code 31. It does so by blinking the engine warning light for 3 long
flashes and 1 short flash.
If no codes are currently
stored, it will simply flash continually, once per second.
I assume that if more than
one code is stored, it will display each one in a repeating sequence,
eg. 31, 52, 64, 31, 52, 64...
To clear the codes, simply
disconnect the car battery for 20 seconds or so.
Note: I found notes
about this procedure on the Smartgroups FTO List, posted by 'troy' in
2001. Legend has it that Dave Hughes originally posted information on
this around 1999. Good work to all concerned!
Thanks also to Rob Jay
for pointing me at a load of extra codes that didn't feature in the