DTC Troubleshooting: U128D (81), 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 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 DTCs with the HDS.


?2.
Turn the ignition switch to LOCK (0) and then back to ON (II), or press the engine start/stop button to select the OFF mode and then the ON mode.

?3.
Do the Self-Diagnostic Function with the HDS or the climate control unit.

?4.
Check for DTCs.
DTC Description
DTC
U128D Lost communication with gauge control module (climate control unit)
  

Is DTC U128D or 81 and/or 83 indicated?

     
YES
     
     
     
Go to step 2.
     
NO
     
     
     
Intermittent failure, the system is OK at this time. Check for loose 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 B-CAN Control Units Information from the Body Electrical System Select menu, and then select Check Connected Control Units.

?2.
Check the DETECT/NOT AVAILABLE information of the GAUGE CONTROL MODULE.

Is DETECT indicated?

     
YES
     
     
     
Go to step 3.
     
NO
     
     
     
Go to step 4.
3.
Open wire check (B CAN-H line):

Open wire check (B CAN-H line)
?1.
Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.

?2.
Disconnect the following connectors.

?3.
Check for continuity between test points 1 and 2.
Test condition
IG LOCK (0) or OFF mode
Gauge control module connector A (32P): disconnected
Climate control unit 32P connector: disconnected
Test circuit
B CAN-H
Test point 1
Gauge control module connector A (32P) No. 30 (PNK)
Test point 2
Climate control unit 32P connector No. 32 (PNK)


Is there continuity?

     
YES
     
     
     
Repair an open or poor connection in the B CAN-L wire between the climate control unit and the gauge control module.?
     
NO
     
     
     
Repair an open or poor connection in the B CAN-H wire between the climate control unit and the gauge control module.?
4.
Fuse check:

Fuse check
?1.
Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.

?2.
Check the following fuses.
Fuse
No. A21 (10 A)
Location
Under-hood fuse/relay box

Fuse
No. B5 (7.5 A)
Location
Under-dash fuse/relay box

Are the fuses OK?

     
YES
     
     
     
Go to step 5.
     
NO
     
     
     
Replace the fuse, and recheck. If the fuse blow again, repair a short in the No. A21 (10 A) or No. B5 (7.5 A) fuse circuit.?
5.
Open wire check (IG1 METER line):

Open wire check (IG1 METER line)
?1.
Disconnect the following connector.

?2.
Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.

?3.
Measure the voltage between test points 1 and 2.
Test condition
IG ON (II) or ON mode
 
Gauge control module connector A (32P): disconnected
Test circuit
IG1 METER
Test point 1
Gauge control module connector A (32P) No. 17 (BRN)
Test point 2
Body ground


Is there battery voltage?

     
YES
     
     
     
The IG1 METER wire is OK. Go to step 6.
     
NO
     
     
     
Repair an open in the IG1 METER wire.?
6.
Open wire check (+B BACK UP line):

Open wire check (+B BACK UP line)
?1.
Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.

?2.
Measure the voltage between test points 1 and 2.
Test condition
IG LOCK (0) or OFF mode
 
Gauge control module connector A (32P): disconnected
Test circuit
+B BACK UP
Test point 1
Gauge control module connector A (32P) No. 1 (WHT)
Test point 2
Body ground


Is there battery voltage?

     
YES
     
     
     
The +B BACK UP wire is OK. Go to step 7.
     
NO
     
     
     
Repair an open in the +B BACK UP wire.?
7.
Open wire check (GND lines):

Open wire check (GND lines)
?1.
Check for continuity between test points 1 and 2 individually.
Test condition
IG LOCK (0) or OFF mode
Gauge control module connector A (32P): disconnected
Test circuit
GND
Test point 1
Gauge control module connector A (32P) No. 4 (BRN)
Test point 2
Body ground

Test circuit
GND
Test point 1
Gauge control module connector A (32P) No. 32 (BRN)
Test point 2
Body ground


Is there continuity?

     
YES
     
     
     
The GND wires are OK. Go to step 8.
     
NO
     
     
     
Check for an open in the wire(s) between the gauge control module and body ground. If the wire(s) is OK, check for poor ground at G502.?
8.
Open wire check (B CAN-H line):

Open wire check (B CAN-H line)
?1.
Disconnect the following connector.

?2.
Check for continuity between test points 1 and 2.
Test condition
IG LOCK (0) or OFF mode
Gauge control module connector A (32P): disconnected
Climate control unit 32P connector: disconnected
Test circuit
B CAN-H
Test point 1
Gauge control module connector A (32P) No. 30 (PNK)
Test point 2
Climate control unit 32P connector No. 32 (PNK)


Is there continuity?

     
YES
     
     
     
Repair an open or poor connection in the B CAN-L wire between the climate control unit and the gauge control module.?
     
NO
     
     
     
Repair an open or poor connection in the B CAN-H wire between the climate control unit and the gauge control module.?