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DTC U1171: PHEV LIN No Bus activity
 
 
caution
  • If there is any problem in the CAN bus lines, an incorrect DTC may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ).
  • Whenever ECU is replaced, ensure that the CAN bus lines are normal.
 
 
DTC SET CONDITIONS
The PHEV-ECU sets DTC U1171 when it cannot communicate via LIN for a certain period.
 
 
 
PROBABLE CAUSES
  • Malfunction of LIN bus line.
  • Malfunction of the battery management unit (BMU).
  • Malfunction of the electrical parking driver unit.
  • Malfunction of the PHEV-ECU.
  • Noise interruption in LIN bus wires.
 
 
 
 
DIAGNOSIS
Required Special Tools
  • MB991223: Wiring harness set
  • MB992006: Extra fine probe
STEP 1. Voltage measurement at LIN bus line
Check if the LIN bus line is shorted to power supply.
(1) The PHEV-ECU, the battery management unit (BMU) and the parking lock driver unit are interconnected via LIN bus lines. Connect a relevant connector of these systems and measure at the wiring harness side.
(2) Turn on the power supply mode of the electric motor switch.
(3) Measure the voltage in LIN1 line between the PHEV-ECU connector and body ground.
OK: No voltmeter reading
noteIf the LIN bus line is shorted to power supply, the voltmeter indicates a constant value.
(4) Measure the voltage in KLNC line between the battery management unit (BMU) connector and body ground.
OK: No voltmeter reading
noteIf the LIN bus line is shorted to power supply, the voltmeter indicates a constant value.
Is the check result normal?
Go to Step 2.
Repair the connector or wiring harness.
 
STEP 2. Resistance measurement at LIN bus line
Check if the LIN bus line is shorted to ground.
(1) Disconnect the PHEV-ECU connector, the battery management unit (BMU) connector or the parking lock driver unit connector, and measure at the wiring harness side.
(2) Check the continuity in LIN1 line between the PHEV-ECU connector and body ground.
OK: No continuity (1 kΩ or more)
(3) Check the continuity in KLNC line between the battery management unit (BMU) connector and body ground.
OK: No continuity (1 kΩ or more)
Is the check result normal?
Go to Step 3.
Repair the connector or wiring harness.
 
STEP 3. Using scan tool (M.U.T.-IIISE), check whether the other DTC is set <Battery management unit (BMU)>
Disconnect the battery management unit (BMU) connector, and check again if DTC U1171 is set.
(1) Connect the PHEV-ECU connector and the parking lock driver unit connector. Then disconnect the battery management unit (BMU) connector only.
(2) Erase the DTC.
(3) Turn off the power supply mode of the electric motor switch.
(4) Turn on the power supply mode of the electric motor switch.
(5) Check whether DTC U1171 is set.
noteIf DTC U1171 is not set, another DTC will be set because the battery management unit (BMU) connector is disconnected. This is not a malfunction.
Is the DTC set?
Connect the battery management unit (BMU) connector, and then go to Step 4.
Replace the battery management unit (BMU) (Refer to ).
 
STEP 4. Using scan tool (M.U.T.-IIISE), check whether the other DTC is set <Electric parking driver unit>.
Disconnect the electric parking driver unit connector, and check again if DTC U1171 is set.
(1) Connect the PHEV-ECU connector and the battery management unit (BMU) connector. Then disconnect the parking lock driver unit connector only.
(2) Erase the DTC.
(3) Turn off the power supply mode of the electric motor switch.
(4) Turn on the power supply mode of the electric motor switch.
(5) Check whether DTC U1171 is set.
noteIf DTC U1171 is not set, another DTC will be set because the parking lock driver unit connector is disconnected. This is not a malfunction.
Is the DTC set?
Connect the parking lock driver unit connector, and then go to Step 5.
Replace the electrical parking driver unit (Refer to GROUP 22A - Front Transaxle ).
 
STEP 5. Using scan tool (M.U.T.-IIISE), check whether the DTC is set again.
Recheck the DTC.
(1) Erase the DTC.
(2) Turn off the power supply mode of the electric motor switch.
(3) Turn on the power supply mode of the electric motor switch.
(4) Check the DTC.
Is the DTC set?
Replace the PHEV-ECU (Refer to ).
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).