Replaced Brake Actuator -- P0A78 P0A94 C1252 C1259 C1310 B1421

I'm short on cash these days and have a donor vehicle, so when my brake actuator went out (constant cycling, C1256 and C1391 codes) I decided to try it myself.

It was hard! I had a lot of trouble getting the actuator to clear the hydraulic lines and water pump / inverter. Then, I had trouble with re-attaching brake lines because the compression fitting nuts did not want to line up correctly. Again, I'm short on money so I took a long time and finally got them all assembled without any cross-threaded fasteners etc.

Then, I powered it up and got ready to bleed the brakes. Lots of warning lights. I powered down again and went to check things. Argh!1! After the long struggle to get things in place and assembled, I had left all the connectors around the inverter loosely connected. I clicked them into place and powered up. I've spent some time clearing codes and researching troubleshooting procedures, and charged the 12V overnight (without disconnecting the negative battery cable, ugh!!!). Could that have damaged things?

I saw another thread on here where someone replaced an accumulator and eventually got the car working by finding broken wires in the wiring harness.

The 12V battery voltage reading is around 11.7V stopped.

I've reserved this weekend to work on it and can follow troubleshooting procedures for the codes. Any helpful advice would be greatly appreciated!

 

Thanks!

I think there may be a 12V problem. After charging, I only got up to 11.9V at the battery and 11.7V at the jumper terminal in the fuse box. It drops about 0.2V, as well, when I connect the negative terminal cable between the battery and the car. Is 11.9 to 11.7V normal or a sign of corrosion, etc.?

I will replace and then see -- at 11.7V this morning I still had the list of codes in the title and a few others. I will be working on it much more this weekend. The 12V battery is < 1 year old, unfortunately.

 

OK! I worked the battery issue and the +B field is 12.71V now as measured at the computer. Some codes disappeared; remaining are C1256 / C1259 / C1310.

I've read that C1259 and C1310 are information codes that mean that other subsystems think there is a problem with the hybrid battery system.

Could the Accumulator not be starting because it thinks the hybrid battery system has a fault and could that cause C1256?

I will, of course, research but if anyone has pointers on fixing C1259/C1310, I would love to hear.

 

For what it is worth, I have re-checked the hybrid battery service plug. I even put a meter on the sensor that detects whether it was installed to ensure that I'm pushing the handle down far enough.

The HV ECU does not report any codes at all and I see battery voltages and such in Techstream.

It is weird, though, that when I try to test the CAN bus in Techstream that it doesn't find any modules to test. On the main screen, all listed modules turn white, which indicates current normal communication. Could I have a CAN bus problem or are these Techstream results normal?

I drained the HV coolant completely, because I splashed some antifreeze into my mouth when removing the hoses on the donor vehicle. I hear the coolant pump running and the tank empties periodically, so it is not all the way full. Could that cause these two codes?