C1310-156, U0073, U0123, U0124, U0126, U0293

The C1310-156 code is set by the Hybrid control system (Enhanced VSC, TRAC system).

The traction control prohibition signal is received for at least 0.07 sec. when IG2 terminal voltage is 10.5 V or more for at least 1.5 sec. and communication with hybrid control ECU is valid.

It would appear that this DTC is set when there is a CAN bus communications problem that prevents the Hybrid Control ECU communicating with the Skid Control ECU. The service manual directs that you need to check the hybrid control system.

The Uxxxx codes mean there is a problem with the communications network.

Have you checked the 12 V battery and ensured you have a good and healthy 12 V supply?

 

Yes check the 12 volt voltage at the front jump points with car off with voltmeter.
Then with car off turn on the headlights on high beam and check voltage at the jumps again.
With headlights on should not be more than a .5 volt drop.

Your describing a hi volt ground fault which can be cleared by bouncing the 12 volt. Usually from leaking electrolyte in the hybrid battery. When u were in the hybrid battery how corroded was everything?

Do you have pictures of the battery?

 

I would say that the main issue your car has is a high voltage ground fault. That is the significance of DTC P0AA6.

As a safety measure the car cannot be started after the fault is logged. However as you learned, a workaround is to disconnect the 12V battery which causes that DTC to be cleared. Then the car can be started once. Since the fault persists, the DTC is logged again, and the car cannot be started until the 12V battery is disconnected once more.

The ground fault may be due to a fault anywhere in the hybrid drivetrain where high voltage is present. Likely faults include leaking electrolyte from a traction battery module, a fault in the traction battery ECU, or a stator winding insulation fault within the transaxle.

It is not clear that the replacement skid control ECU is helping since you now have DTC C1300 which indicates a failed ECU. Or maybe you damaged the associated wiring harness connector.

Further, you need to fully-charge the 12V battery. That is the meaning of DTC C1241.

 

That test is effective if the leak is bad enough to quickly trip the code. Give it a try.

 

Congratulations and respect for being able to get that top mounting nut off. Did you bother putting it back on?

 

The traction battery is isolated from body ground. Neither the positive nor negative leads from the battery should be connected to body ground. This is required for safety reasons.

In your pictures, substantial corrosion on the traction battery case is evident. This came from electrolyte leaking from one or more modules. The electrolyte is clear and not easy to see; however if a module has corrosion on a terminal that is good evidence that the module is leaking.

The electrolyte leaking to the battery case sheet metal causes an electrical path to body ground, hence a ground fault results.

 

Did you clean the case to remove all traces of electrolyte from the case and all the modules? If you didn't you will be back in there as soon as it gets damp.

 

How does one clean the case?

So I'm getting the P0A80 and UOO73 error codes. I'm trying to figure out what exactly is wrong with my Prius. When the slip indicator pops up with check engine and triangle and (!) Then slip and (!) Disappear shortly after . My ecu and pwr and eco mode stop working as well as the energy monitor when these codes pop up. Any idea?

 

Replace the HV battery if you can.

 

Thank you for posting the fix. This has helped me fix mine