Flash codes

Task:
       -Find an engine that you have the workshop manual with the correct procedure and codes to diagnose the flash codes.
       -have your tutor create a fault in the efi system
       -using the workshop manual  follow the procedure to extract the codes, explain briefly what is the procedure.
The engine i chose to extract the flash codes from was a 4a-fe toyota 4 cyl motor.During this test the engine is off but the ignition is on.
the procedure to extracting the codes: -locate diognostic plug and open flap
                                                          -bridge pins "TE1" and "E1" with a fused jumper wire
                                                          -the engine light will display on dash
if a fault is present the engine light will flash as long as the pins te1 and e1 are bridged, there will be a series of flashes and to read these yo record the number of flashes. The fisrst set of flashes is the "10's" of the code i.e if the engine light were to flash 3 times it would mean it is 30. After the 1st set there will be a pause and another set of flashes will happen and this is the "1's" of the code i.e. if the engine light flashed 1 time it would mean the 2nd digit of the overall code would be 1, now you add the 10's and 1's together to get the code which in this case its 31 and i can now go to the manual and look up what that code is and it is the vaccum sensor (MAP sensor).

The tutor put 3 faults in and by following the procedure above i diagnosed the codes and got the ones in the chart below.

Code number	System affected	Condition described
22	Water temp sircuit	Unplugged
31	Vaccum sensor (map sensor)	Unplugged
41	Throttle position	unplugged

Other conditions that could cause these systems to be affected could be that the plug is corroded, wires to the sensor could be incorectly probed and split causing high resistance in that particular circuit. to repair the above faults all i had to do was plug all of them back in but if the plugs were to be corroded or the wires were exposed i would replace immediatly.
Once the faults are repaired the fault codes were still present and needed to be cleared, to do this all i had to do was turn the ignition off and take the jumper wire out and then rechecked that the codes had gone i turned the ignition on and started the engine and the the engine light switched off soon after the engine was started and the engine ran fine.
In result of these faults the engine would not run right because the ECU was not getting any signals from the sensors affected E.g. the water temp sensor was unpluged which meant the ECU was receiving 0.0 volts which told the ECU to run lean because it thinks the engine is really hot.