Touchscreen Display Inoperative (PS595)

Publication date: 2019-05-13
Reference number: PS595

TOUCHSCREEN DISPLAY INOPERATIVE

TECHNICAL SERVICE BULLETIN

Reference Number(s): PS595, Date of Issue: May 13, 2019

KIA:	All Models with Touchscreen
GROUP:	Electrical

SERVICE INFORMATION

This Pitstop provides information regarding an inoperative head unit touch screen and is applicable to all touch screen equipped models. Before attempting to swap the head unit or performing a capacitive discharge , disconnect the steering wheel switch and check to see if the head unit touchscreen begins to function normally. If disconnecting the switch does restore touchscreen input, suspect a possible faulty switch or issue in the switch wiring.

Changes in circuit voltage by use of resistors switching are used to signal which button is being pressed, as visible in the example schematic below (Figure 1). If a button gets stuck, or if the harness develops excessive resistance, the inadvertent voltage change causes an error.

A voltage change will cause the Audio Unit to react as if it is getting an input from the switch, at which point it will by design ignore the touch screen input. Swapping in a known good Audio Head Unit as a result of misdiagnosis can result in resetting the system which may only temporarily fix the concern, leading to a come back.