Allison 6sp: Transmission acting strange

[Duallychick2014]

The other day the transmission in my 2006 GMC Duramax dually started acting a little strange it didn’t really feel like it was slipping and it didn’t shift hard it was delayed it felt like it was between second to third once the truck warms up it seems to go away my husband hooked his scanner up to it and the trans had a code U1300 and he also found this I don’t know if it means anything if anyone can offer some advice I’d really appreciate it .

1-2 sol. CKT status- indeterminate short to volts
2-3 sol. CKT status- indeterminate short to volts

 

[ZeroGravity58]

Diagnostic Instructions

DTC U1300
Class 2 Data Link Low

DTC U1301
Class 2 Data Link High

DTC U1305
Class 2 Data Link High or Low


Circuit Description

Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. In addition to this, Node Alive messages are transmitted by each module on the class 2 serial data circuit about once every 2 seconds. When the module detects high or low voltage on the class 2 serial data circuit for approximately 3 seconds, the setting of all other class 2 serial communication DTCs is inhibited and a DTC will set.

Conditions for Running the DTCs



Voltage supplied to the module is in the normal operating voltage range.
The vehicle power mode requires serial data communication to occur.
Conditions for Setting the DTCs

The class 2 serial data circuit is shorted high or low for approximately 3 seconds.

Maybe you have a shirt to ground???

 

[Duallychick2014]

So possibly a loose connection or a broke wire somewhere

 

[ZeroGravity58]

The data link runs between all the computers on the truck. It could be a loose wire, corrosion, etc. I'd pull all the connections and check them to start.