Hyundai Sonata 1991 Shop Manual page 181

AUTOMATIC SPEED CONTROL (CRUISE)
Trouble Symptom
2
ASC system cannot be set
NOTE
If. after the occurrence of the problem, the ignition switch and
the cruise main switch have not been switched OFF, it is pos-
sible to determine (by checking the diagnosis output code)
which circuit canceled the system's operation.
This chart is to be used, then, for troubleshooting if it is not
possible to use the self-diagnosis for checking.
Check the ECU power supply circuit
No
o Damaged or disconnected wiring of the ECU power-
and SET or RESUME switch. Is there
supply circuit
normal?
o Damaged or disconnected wiring of the SET or RESUME
Yes
switch
Check the input check
items
Input check items
Probable ca use Remedy
SET switch ON malfunction Replace the control switch
SET switch input line short-circuit Repair the harness
RESUME switch ON malfunction Replace the control switch
RESUME switch input line short-circuit
Repair the harness
Malfunction of the CANCEL circuit (ON mal- Check or repair each CANCEL circuit
function)
Malfunction of the vehicle-speed sensor cir-
Check or repair the vehicle speed sensor cir-
cuit
(damaged or disconnected wiring, or
cuit
short-circuit)
Normal
Check the actuator circuit
NOTE
If the results of the check of the actuator circuit and of the
actuator itself reveal no abnormal condition, replace the elec-
tronic control unit (ECU)
27-62