CAN Communication Line Inspection
■ Inspection procedure for impedance measurement
When measuring impedance, 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:
- The CAN bus must be disconnected from the power supply.
- The measurement is taken between the CAN High and CAN Low leads.
- The measurement recorded may differ from the specified levels by a few ohms.
■ Impedance measurement with matching resistor
- Ignition "OFF" and disconnect the battery and wait about four minutes.
- Make sure all modules are properly connected.
- Measure resistance between Pin No. 13 (P-CAN High) and Pin No. 14 (P-CAN Low) terminal of IGPM harness connector.
Specification: Approx. 60 Ω
- Is the measured value within specification?
YES
- Go to "CAN Signal Inspection" procedure below.
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
- Ignition switch "OFF"
- Disconnect battery (-) cable.
- Refer to "REMOVAL and REMOVAL " and disconnect PCM and IGPM connector.
- Measure the resistance between Pin No. 13 (P-CAN High) and Pin No. 14 (P-CAN Low) terminal of IGPM.
- Measure the resistance between Pin No. 10 (P-CAN High) and Pin No. 35 (P-CAN Low) terminal of PCM.
Specification: Approx. 120 Ω
- Is the measured value within specification?
YES
- Go to "CAN Signal Inspection" procedure below.
NO
- Carefully re-do this troubleshooting guide steps.
- If no problems were found with the circuits or connectors, replace IGPM or PCM and then go to "VERIFICATION OF VEHICLE REPAIR " procedure.
■ CAN Signal Inspection
- Ignition switch "OFF"
- Connect VMI to GDS and launch the oscilloscope (2 Channel):
Channel A (+): Pin No. 13 (P-CAN High) terminal (IGPM connector)
Channel A (-): Ground
Channel B (+): Pin No. 14 (P-CAN Low) terminal (IGPM connector)
Channel B (-): Ground
- Ignition switch "ON"
Specification: C-CAN High voltage - Approx. 2.8V/C-CAN Low voltage - Approx. 2.2V (Average)
- Is the 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
- Repair open or short in P-CAN communication line and then, go to "VERIFICATION OF VEHICLE REPAIR " procedure.
- If problem keep occurs, go to "COMPONENT INSPECTION " procedure.
■ Open in CAN communication line inspection
- Ignition OFF.
- Disconnect Battery (-) terminal.
- Disconnect IGPM and ESC.
- Measure resistance between Pin No. 13 (P-CAN High) terminal of IGPM and Pin No. 26 (P-CAN High) terminal of ESC.
- Measure resistance between Pin No. 14 (P-CAN Low) terminal of IGPM and Pin No. 14 (P-CAN Low) terminal of ESC.
Specification: Approx. below 1 Ω
- Is the 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
- Repair open or short in P-CAN communication line and then, go to "VERIFICATION OF VEHICLE REPAIR " procedure.
- If problem keep occurs, go to "COMPONENT INSPECTION " procedure.