With manual transaxle
Press the engine start/stop button when the button is in the ACC position without depressing the clutch pedal.
With automatic transaxle/DCT
Press the engine start/stop button while it is in the ACC position without depressing the brake pedal.
The warning lights can be checked before the engine is started. Do not leave the engine start/stop button in the ON position for a long time. The battery may discharge, because the engine is not running.
Kia Cee'd JD Service Manual: A/C Pressure Transducer Repair procedures
Inspection
1.
Measure the pressure of high pressure line by measuring voltage output
between terminal “1” and “2”.
2.
Inspect the voltage value whether it is sufficient to be regular value
or not.
...
Kia Cee'd JD Service Manual: Repair procedures
Inspection
Test the horn by connecting battery voltage to the 1 terminal and ground the
2 terminal.
The horn should make a sound. If the horn fails to make a sound, replace it.
Horn Relay Inspection
1.
Remove the horn relay (A) from the engine room ...