Hyundai Sonata 1991 Shop Manual page 264

MPI SYSTEM
o Motor position sensor
o Engine coolant temperature sensor
o Crank angle sensor
o No.1 cylinder top dead center sensor
o Injector
o Fuel pump
o EGR temperature sensor (Only California Vehicles)
SELF-DIAGNOSIS
Y310VOA
The engine control unit monitors the input/output signals (some
signals at all times and the others under specified conditions)
of the engine control unit.
When it is noticed that an irregularity has continued for a spec-
ified time or longer from when the irregular signal is initially mon-
itored,passing a certain number, the engine control unit judges
that an irregularity has occurred, memorizes the trouble code,
and outputs the signal to the self-diagnosis output terminal.
There are 14 diagnosis items, including the normal state, and
the diagnosis results can be read out with a voltmeter or mul-
ti-use tester.
Moreover, since memorization of the trouble codes is backed up
directly by the battery, the diagnosis results are memorized even
if the ignition key is turned off. The trouble codes will, however,
be erased when the battery terminal or the engine control unit
connector is disconnected.
CAUTION
If the sensor connector is disconnected with the ignition
switch turned on, the diagnosis code is memorized, In this
case, disconnect the battery negative terminal (-) for 15
seconds or more, and the diagnosis memory will be erased.
The 13 diagnosis items are provided as follows, and if plural
items are activated, they are all indicated sequentially from the
smallest code number.
Trouble code
Diagnosis item
Trouble code Diagnosis item
11 Oxygen sensor
23
No.1 cylinder top dead center sensor
12
Air-flow sensor
24
Vehicle-speed reed switch
13 Air temperature sensor
25
Atmospheric pressure sensor
14 Throttle position sensor
41
Injector
15 Motor position sensor
42 Fuel pump
21 Engine coolant temperature sensor
43 EGR temperature sensor (For Califor-
22 Crank angle sensor
nia Vehicles)
31-39