Circuit Inspection

Courtesy of KIA MOTORS AMERICA, INC.

P-CAN Inspection
Inspection Item	Inspection Condition	(+) Probe		(-) Probe		Specification
		Connector	Terminal	Connector	Terminal
Resistance inspection (VCU, ICU)	Ignition "OFF". Disconnect auxiliary battery (-) cable. Disconnect the connector(s) VCU, ICU.	VCU (component side)	77 (P-CAN high)	VCU (component side)	78 (P-CAN low)	Approx. 120Ω
		ICU (component side)	19 (P-CAN high)	ICU (component side)	20 (P-CAN low)	Approx. 120Ω
Open in circuit inspection (SCU ↔ ICU)	Ignition "OFF". Disconnect the connector(s) SCU, ICU.	SCU connector	6 (P-CAN high)	ICU connector	19 (P-CAN high)	Approx. below 1Ω
		SCU connector	7 (P-CAN low)	ICU connector	20 (P-CAN low)	Approx. below 1Ω
P-CAN oscilloscope (SCU)	Ignition "ON". Measure the waveform using VMI of KDS.	SCU connector	6 (P-CAN high)	Chassis ground	-	Fig.1 to 6
		SCU connector	7 (P-CAN low)	Chassis ground	-

Information 

It is important to check CAN high and low at the same time to check the waveform of the CAN communication line. The CAN signal is in a bus idle state based on 2.5V (digital "1"), the high signal rises to 3.5V, the low signal falls to 1.5V, and the voltage difference between the high and low signals is "0" when 2V occurs. Is detected. In addition, it monitors whether the high and low signals have opposite voltages based on 2.5V like the waveform on the left, and monitors whether the current CAN signal is transmitted normally.

In CAN communication, a continuous "0" signal of 6 bits or more means occurrence of an error. 1 bit can be easily determined by obtaining the time when "SOF" (Start Of Frame), indicating the start of the frame, occurs. Check if the "0" signal of 6 bits or more occurs continuously during CAN communication waveform check.

1. Reference voltage about 2.5V (high: 2.5V → 3.5V rise, low: 2.5V → 1.5V drop)
2. Idle (2.5V) section of a certain period
3. Constant data frame time
4. High and low symmetrical frame shape

Courtesy of KIA MOTORS AMERICA, INC.

Courtesy of KIA MOTORS AMERICA, INC.

Courtesy of KIA MOTORS AMERICA, INC.

Courtesy of KIA MOTORS AMERICA, INC.

Courtesy of KIA MOTORS AMERICA, INC.

Courtesy of KIA MOTORS AMERICA, INC.

Good 

• Go to "Module Inspection" procedure.

No Good 

• Repair open or short in circuit and then go to "Verification of Repair " procedure.

Module Inspection
Inspection Item	Inspection Condition	(+) Probe		(-) Probe		Specification
		Connector	Terminal	Connector	Terminal
Power inspection (SCU ↔ Chassis ground)	Disconnect the connector(s) SCU. Ignition "ON".	SCU connector	10 (memory input)	Chassis ground	-	B+
		SCU connector	16 (IG3 input)	Chassis ground	-	B+
Open in circuit inspection (SCU ↔ Chassis ground)	Ignition "OFF". Disconnect the connector(s) SCU.	SCU connector	9, 19, 20 (ground)	Chassis ground	-	Approx. below 1Ω

Good 

• Go to "COMPONENT INSPECTION " procedure.

No Good 

• Repair open or short in circuit and then go to "Verification of Repair " procedure.