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U1D20-87 Communication error between HVAC2 and ENGINE ECU
 
 
caution
  • If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines.
  • Before replacing the ECU, ensure that the CAN bus lines is normal.
 
 
MONITOR EXECUTION
Continuous
 
 
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
  • Not applicable
Sensor (The sensor below is determined to be normal)
  • Not applicable
 
 
DTC SET CONDITIONS
Logic Flow Chart
 
 
TROUBLE JUDGMENT
Check Condition
  • The power supply mode of the electric motor switch is ON (READY indicator: ON)
  • The heater PHEV A/C amp. power supply voltage is between 10 and 16 volts.
  • Time after above conditions satisfy is 5 seconds or more
Judgment Criterion
  • The CAN signal from the ECU can not be received for 2.5 seconds or more.
 
 
OBD-II DRIVE CYCLE PATTERN
 
 
PROBABLE CAUSES
  • Malfunction of CAN bus lines (HV1-CAN)
  • Malfunction of ECM power supply circuit
  • Malfunction of ECM
  • Malfunction of PHEV A/C amp.
 
 
DIAGNOSIS PROCEDURE
1.M.U.T.-III SE CAN bus diagnosis
Use M.U.T.-III SE to diagnose the CAN bus line.
Is the inspection result normal?
Repair the CAN bus line. (Trouble Diagnosis Flow Chart)
 
2.M.U.T.-III SE other DTC
Check whether the PHEV-ECU sets the DTC (No. U2340-87) related.
Check whether the BMU sets the DTCs (No. U0100-00 or U2340-87) related.
Are the DTCs set?
 
3.Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to OBD-II Drive Cycle - Pattern 4 OBD-II DRIVE CYCLE.
(2) Check the DTC.
Is the DTC set?
Replace ECM Refer to ENGINE CONTROL MODULE (ECM) REMOVAL AND INSTALLATION, then
The trouble can be an intermittent malfunction. Refer to General Information - How to Use Troubleshooting/Inspection Service Points, How to Cope with Intermittent Malfunctions HOW TO COPE WITH INTERMITTENT MALFUNCTIONS.
 
4.Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to OBD-II Drive Cycle - Pattern 4 OBD-II DRIVE CYCLE.
(2) Check the DTC.
Is the DTC set?
Replace PHEV A/C amp. Refer to Removal and Installation.
The trouble can be an intermittent malfunction. Refer to General Information - How to Use Troubleshooting/Inspection Service Points, How to Cope with Intermittent Malfunctions HOW TO COPE WITH INTERMITTENT MALFUNCTIONS.