DTC Troubleshooting: U128D (81), U128D (82), U128D (83)
DTC U128D: Lost Communication with Gauge Control Module (Climate Control Unit)
DTC Indicator 81: Climate Control Unit Lost Communication with Gauge Control Module (ECT message)
DTC Indicator 82: Climate Control Unit Lost Communication with Gauge Control Module (ILLUMI message)
DTC Indicator 83: Climate Control Unit Lost Communication with Gauge Control Module (VSP message)
DTC Description
DTC
U128D Lost Communication with Gauge Control Module (Climate Control Unit)
  

1.
Problem verification:

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 HDS or the climate control unit.

?5.
Check for DTCs.
DTC Description
DTC
U128D Lost Communication with Gauge Control Module (Climate Control Unit)
  

Is DTC U128D or 81, 82, and/or 83 indicated?

     
YES
     
     
     
Go to step 2.
     
NO
     
     
     
Intermittent failure, the system is OK at this time. Check for loose wires or poor connections.?
2.
Determine possible failure area (gauge control module power and ground, B-CAN lines):

Determine possible failure area (gauge control module power and ground, B-CAN lines)
?1.
Select Gauges from the Body Electrical System Select menu, and then select Data List.

Does the Data List appear?

     
YES
     
     
     
Go to step 3.
     
NO
     
     
     
Go to step 5.
3.
Open wire check (B-CAN_H line):

Open wire check (B-CAN_H line)
?1.
Turn the vehicle to the OFF (LOCK) mode.

?2.
Disconnect the following connectors.
Gauge control module 32P connector
Climate control unit 32P connector

?3.
Check for continuity between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
Gauge control module 32P connector: disconnected
Climate control unit 32P connector: disconnected
Test point 1
Gauge control module 32P connector No. 23
Test point 2
Climate control unit 32P connector No. 19

Is there continuity?

     
YES
     
     
     
The B-CAN_H wire is OK. Go to step 4.
     
NO
     
     
     
Repair an open in the wire between the climate control unit and the gauge control module.?
4.
Open wire check (B-CAN_L line):

Open wire check (B-CAN_L line)
?1.
Check for continuity between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
Gauge control module 32P connector: disconnected
Climate control unit 32P connector: disconnected
Test point 1
Gauge control module 32P connector No. 24
Test point 2
Climate control unit 32P connector No. 21

Is there continuity?

     
YES
     
     
     
The B-CAN_L wire is OK. Replace the gauge control module.?
     
NO
     
     
     
Repair an open in the wire between the climate control unit and the gauge control module.?
5.
Fuse check:

Fuse check
?1.
Turn the vehicle to the OFF (LOCK) mode.

?2.
Check the following fuse.
Fuse
No. B21 (10 A)
Location
Under-hood fuse/relay box

Is the fuse OK?

     
YES
     
     
     
Go to step 6.
     
NO
     
     
     
Replace the fuse, and recheck. If the fuse blows again, repair a short in the No. B21 (10 A) fuse circuit.?
6.
Open wire check (+B BACK UP line):

Open wire check (+B BACK UP line)
?1.
Disconnect the following connector.
Gauge control module 32P connector

?2.
Measure the voltage between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
 
Gauge control module 32P connector: disconnected
Test point 1
Gauge control module 32P connector No. 16
Test point 2
Body ground

Is there battery voltage?

     
YES
     
     
     
Check for an open in the wire between the gauge control module and body ground. If the wire is OK, check for poor ground at G401.?
     
NO
     
     
     
Repair an open in the wire between the No. B21 (10 A) fuse in the under-hood fuse/relay box and the gauge control module.?