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CAN Communication Line Inspection

Inspection procedure for resistance measurement 

When measuring resistance, it is generally necessary to disconnect the circuit being tested from the power supply before hand. The vehicle's battery should therefore be disconnected and wait about four minutes to allow all capacitors in the system to discharge.

Inspection procedure for resistance test:

  1. The CAN bus must be disconnected from the power supply
  2. The measurement is taken between the CAN High and CAN Low leads
  3. The measurement recorded may differ from the specified levels by a few ohms

Resistance measurement with matching resistor 

  1. Ignition "OFF" and disconnect the battery and wait about four minutes.
  2. Make sure all modules are properly connected.
  3. Measure resistance between Pin No. 13 (CAN High) and Pin No. 14 (CAN Low) terminal of IGPM.

    Specification:  Approx. 60Ω

  4. Is the measured value within specification?

    YES 

    • Check each module connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and then go to "VERIFICATION OF VEHICLE REPAIR " procedure.

    NO 

    • If the measured value is out of specification, go to "CAN resistor inspection" procedure below.

    * If the measured value is approx. 0Ω, then check for short CAN communication line.

    * If the measured value is approx. 120Ω, then check for open CAN communication line of control module with resistor.

CAN resistor inspection 

  1. Ignition OFF.
  2. Disconnect Battery (-) terminal.
  3. Disconnect PCM and IGPM connectors.
  4. Measure resistance between Pin No. 60 (P-CAN Low) and Pin No. 77 (P-CAN High) terminal of PCM.
  5. Measure resistance between Pin No. 14 (P-CAN Low) and Pin No. 13 (P-CAN High) terminal of IGPM.

    Specification:  About 120Ω

  6. Is the measured value within specification?

    YES 

    • Go to "next" procedure.

    NO 

    • Carefully re-do this troubleshooting guide steps.
    • If problem still occurs, replace PCM or IGPM whichever has Faulty resistor and then go to "VERIFICATION OF VEHICLE REPAIR " procedure.

CAN Communication Line Inspection 

  1. Ignition "ON"
  2. Measure voltage between Pin No. 13 (P-CAN High) terminal of IGPM and chassis ground.
  3. Measure voltage between Pin No. 14 (P-CAN Low) terminal of IGPM and chassis ground.

    Specification:  CAN High Voltage - Approx. 2.6V/CAN Low Voltage - Approx. 2.4V

  4. Is measured value within specification?

    YES 

    • Fault might be intermittent and caused either by poor contact in connectors or wiring harness, or it has been repaired and control module memory is not cleared yet. Thoroughly check terminal of battery, all connectors (and connections) for looseness, bending, corrosion, contamination, deterioration, and/or damage.
    • Repair or replace as necessary and then go to "VERIFICATION OF VEHICLE REPAIR " procedure.

    NO 

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