C1102 Battery Voltage Low - Automotive Repair Guides & Equipment

COMPONENT LOCATION

GENERAL DESCRIPTION

EPS CM controls EPS solenoid current accurately according to vehicle speed. EPS CM monitors that operating voltage supplied as IG S/W is too high or too low on “power supply terminal”. If excessive high voltage or low voltage is detected, EPS CM stops current supply to solenoid to prevent unexpected operation or damage.

DTC DESCRIPTION

EPS CM sets this code if high voltage caused by faulty alternator or poor connention in power supply circuit is detected.

DTC DETECTING CONDITION

Item

Detecting Condition

Possible cause

DTC Strategy

Battery Voltage Monitoring

Open/short in power circuit.

Faulty ground circuit.

Faulty charging system.

Enable conditions

Engine “ON”

Threshold value

When Vign is higher than 18V for more than 400ms.

Fail Safe

EPS warning lamp “ON”

Restoration conditions

When Vign is lower than 17V for more than 400ms.

SPECIFICATION

Bat. Voltage	IG Key ON	ENG. ON
Bat. Voltage	Approx. 11.8 [V]~12.5 [V]	Approx. 12.5 [V] ~ 14.5 [V]

DIAGNOSTIC CIRCUIT DIAGRAM

MONITOR SCANTOOL DATA

1.	Connect scantool to Data Link Connector(DLC).

2.	Start engine and turn the headlight on.

3.	Monitor the “BATTERY VOLTAGE” parameter on the scantool.

Maintaining ENG. RPM at 2,500RPM(idle) over 2 minutes.

less than 17 [V]

Is parameter within specifications?

	▶ Fault is intermittent and caused either by poor contact in connectors or wiring harness, or it has been repaired and EPS CM memory is not cleared yet. Thoroughly check all connectors (and connections) for looseness, bending, corrosion, contamination, deterioration, and/or damage. ▶ Repair or replace as necessary.
	▶ Go to “W/Harness Inspection” procedure.

TERMINAL AND CONNECTOR INSPECTION

1.	Many malfunctions in the electrical system are caused by poor harness and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.

2.	Thoroughly check all connectors (and connections) for looseness, bending, corrosion, contamination, deterioration, and/or damage.

Has a problem been found?

	▶ Repair as necessary and then go to “Verification of Vehicle Repair” procedure.
	▶ Go to “Charging System Inspection” procedure.

CHARGING SYSTEM INSPECTION

1.	Engine “ON”

2.	headlight”ON”.

Measure voltage between terminal (+) and (-) of battery while maintaining ENG RPM 2,500RPM over 2 minutes.

Less than 17 [V]

Is the measured voltage within specifications?

	▶ Go to “Power Circuit Inspection” procedure.
	▶ Check that the tension of drive belt, ENG RPM, fuse, terminal of battery, all terminals of alternator are in good condition and Check for damaged harness and poor connection between alternator and battery. ▶ Repair as necessary.

POWER CIRCUIT INSPECTION

■ Open or Short Check

1.	Ignition “OFF”

2.	Disconnect EPS CM connector.

3.	Engine “ON”, headlight “ON”.

Measure voltage between battery power terminal of EPS CM harness connector and chassis ground maintaining ENG. RPM at 2,500RPM(idle) over 2 minutes.

less than 17 [V]

Is the measured voltage within specifications?

	▶ Go to “Ground Circuit Inspection” procedure.
	▶ Check for open or blown fuse referring to “Circuit Diagram”. Repair open or short in power circuit between battery and EPS CM harness connector .

GROUND CIRCUIT INSPECTION

■ Open or Short Check

1.	Ignition “OFF”.

2.	Disconnect EPS CM connector.

Measure resistance between ground terminal of EPS CM harness connector and chassis ground.

Approx. 1.0 Ω

Is the measured resistance within specifications?

	▶ Substitute with a known-good steering column & EPS unit assembly and check for proper operation. If the problem is corrected, replace steering column & EPS unit assembly
	▶ Check for open or contact resistance in ground harness. Repair as necessary.

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