DTC U1281 (I-A3), U1281 (91), U128D (I-A2), U128D (83), U1290 (I-A6), U1290 (8F) (Climate Control Unit)

DTC U1281, DTC screen I-A3, or DTC screen 91  : Climate Control Unit Lost Communication with MICU (body control module)

DTC U128D or DTC screen I-A2  : Climate Control Unit Lost communication with gauge control module

DTC U128D or DTC indicator 83  : Climate Control Unit Lost Communication with Gauge Control Module (VSP Message)

DTC U1290 or DTC screen I-A6  : Climate Control Unit Lost Communication With Seat Heater Control Unit (Front)

NOTE: 

• According to the detected DTC(s), check for the power circuit and the ground circuit of the control unit which cannot communicate with the climate control unit.
• Refer to the DTC shown on the display, then inspect the connectors and terminals based on the instructions.

DTC (AC)

1. Problem verification

   -1. Clear the DTC with the HDS.

   -2. Turn the vehicle to the OFF (LOCK) mode and then the ON mode.

   -3. Wait for at least 6 seconds.

   -4. Do the Self-Diagnostic Function with the climate control unit .

   -5. Check for DTCs.

   DTC Description	DTC
   U1281 Climate Control Unit Lost Communication with MICU (body control module)
   U128D Climate Control Unit Lost communication with gauge control module
   U1290 Climate Control Unit Lost Communication With Seat Heater Control Unit

   Are any DTCs indicated?

   YES 

   The failure is duplicated. Go to step 2.

   NO 

   Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the transmitting control units and the climate control unit.

2. Open wire check (B-CAN_H line, B-CAN_L line)

   -1. Turn the vehicle to the OFF (LOCK) mode.

   -2. Disconnect the receiving control unit connector.

   Climate control unit connector A (32P)

   -3. Disconnect the transmitting control unit connector(s).

   Refer to the DTC shown on the display, then disconnect the connector(s) based on the instructions (see table).

   DTC	Connector
   U1281	Body control module connector B (36P)
   U128D	Gauge control module connector A (32P)
   U1290	Front seat heater control unit 24P connector

   -4. Measure the resistance between the receiving control unit and the transmitting control unit on the B-CAN_H circuit and the B-CAN_L circuit.

   Test condition	Vehicle OFF (LOCK) mode
   	Climate control unit connector A (32P): disconnected
   	Transmitting control unit connector(s) for indicated DTCs: disconnected

   DTC	Circuit name	Test point 1 (Receiving control unit)		Test point 2 (Transmitting control unit)
   		Connector	Terminal	Connector	Terminal
   U1281	B-CAN_H	Climate control unit connector A (32P)	No. 25	Body control module connector B (36P)	No. 20
   	B-CAN_L		No. 8		No. 21
   U128D	B-CAN_H	Climate control unit connector A (32P)	No. 25	Gauge control module connector A (32P)	No. 30
   	B-CAN_L		No. 8		No. 31
   U1290	B-CAN_H	Climate control unit connector A (32P)	No. 25	Front seat heater control unit 24P connector	No. 10
   	B-CAN_L		No. 8		No. 9

   Is there 1.0 Ω or less?

   YES 

   The B-CAN_H wire and B-CAN_L wire is OK.Refer to the DTC shown on the display, then substitute or replace the control unit based on the instructions (see table).

   DTC	Operation for transmitting control unit
   U1281	Substitute a known-good body control module , then recheck. If DTC U1281 goes away after substitution, replace the original body control module .
   U128D	Substitute a known-good gauge control module , then recheck. If DTC U128D goes away after substitution, replace the original gauge control module .
   U1290	Substitute a known-good front seat heater control unit , then recheck. If DTC U1290 goes away after substitution, replace the original front seat heater control unit .

   NO 

   Repair an open in the B-CAN_H wire and/or the B-CAN_L wire between the climate control unit and the transmitting control unit.