Kia Rio: Charging System / DC/DC Converter

Kia Rio 2017-2021 YB Service Manual / Engine Electrical System / Charging System / DC/DC Converter

Description and operation

Due to the considerably more frequent occurrence of starting operations, the electrical load that occurs often leads to voltage dips in the vehicle network.

In order to stabilize the power supply for certain voltage-sensitive electrical components, a DC/DC converter is used in conjunction with the ISG function.

The DC/DC converter supplies the relay with a voltage that also remains constant during the starting operation.

The DC/DC converter is fitted at the behind of the glove box.

Via the test leads for input voltage and the start relay , the electronics decide whether the power is supplied to the output via the bypass or the DC/DC converter.

In the bypass mode, the on-board supply voltage is not fed across the DC/DC converter, rather is transferred directly to the outputs. In the booster phase, the vehicle voltage is adapted.

Operation Principle


In the ISG mode, if the power of an audio system turns OFF by drawdown while “Auto Starting” or “Idle Starting” function operates, replace the DC/DC converter.

Components and components location
Component Location

1. DC/DC converter (LHD)
2. DC/DC converter (RHD)

Schematic diagrams
Circuit Diagram

Repair procedures

Disconnect the battery negative terminal.


Remove the glove box housing.

(Refer to Body - "Glove Box Housing")


Disconnect the DC/DC converter conector (A).


Remove the DC/DC converter (B) after removing nuts.

DC/DC converter installation nut:

4.0 - 6.0 N·m (0.4 - 0.6 kgf·m, 3.0 - 4.4 lb·ft)




Install in the reverse order of removal.


After reconnecting the battery negative cable, ISG function dose not operates until the system is stabilized, about 4 hours.

If disconnecting the negative (-) battery cable from the battery during repair work for the vehicle equipped with ISG function, Battery sensor recalibration procedure should be performed after finishing the repair work.

(Refer to Charging System - "Battery Sensor")

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