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M-CAN Inspection

Inspection Item Inspection Condition (+) Probe (-) Probe Specification
Connector Terminal Connector Terminal
Resistance inspection (AVNT, ICU)
  1. Ignition "OFF".
  2. Disconnect the AVNT, ICU connector
 AVNT (component side) 7 (M-CAN high) AVNT (component side) 20 (M-CAN low) Approx. 120Ω
ICU (component side) 31 (M-CAN high) ICU (component side) 32 (M-CAN low) Approx. 120Ω
Open in circuit inspection (HUD ↔ ICU)
  1. Ignition "OFF".
  2. Disconnect the HUD, ICU connector.
 HUD connector 9 (M-CAN high) ICU connector 31 (M-CAN high) Approx. below 1Ω
HUD connector 3 (M-CAN low) ICU connector 32 (M-CAN low) Approx. below 1Ω
M-CAN oscilloscope (HUD)
  1. Ignition "ON".
 HUD connector 9 (M-CAN high) Chassis ground - Fig.1 to 6
HUD connector 3 (M-CAN low) Chassis ground -

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.
    G15828558Courtesy of KIA MOTORS AMERICA, INC.
    G15828559Courtesy of KIA MOTORS AMERICA, INC.
    G15828560Courtesy of KIA MOTORS AMERICA, INC.
    G15828561Courtesy of KIA MOTORS AMERICA, INC.
    G15828562Courtesy of KIA MOTORS AMERICA, INC.
    G15828563Courtesy of KIA MOTORS AMERICA, INC.

    Good 

    • Go to "MODULE INSPECTION" procedure.

    No Good 

    • Check for a short circuit between the wiring and the chassis ground.
    • Perform repair or replacement as necessary and perform the "Verification of Repair " procedure.
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