2005 over 380K replaced some Cells now HV System Warning Light but no ODB DTC Codes

Hi Everyone,

This forum is the best, it has saved me so much time and lots of money over the years. So a long overdue thanks.

So I am writing about a 2005 Black Prius that is the 2nd of five Prius that our family has had. This Prius has well over 299,999 miles on it (my wife estimates over 380,000 miles) the battery pack has maybe 50 to 70K less miles then that, having come from a wreck.

The other day the Prius stopped moving, was throwing P0A80 (Replace HV Battery Pack). So I replaced 10 cells and got the voltage to match up within 0.3V (range was from 7.6V to 7.3V). I have done this on a Prius I was driving and supervised my kids doing it on two others, so I am familiar with this process. I reinstalled the battery pack and then was getting P0AA4 (negative relay stuck closed). I cleared the code, but the warning lights would come right back on. And after a few attempts to start also once got P0AC0 (current sensor A Range/Performance).

I charged each cell individually and that seemed to get rid of the P0AC0 code.

I tested the relays they all tested in spec, when I reinstalled the positive and negative relays I switched them but still got the P0AA4 (negative relay Stuck closed) so this seems to mean the relays are fine but something else was wrong with what the diagnostics routine depends on (maybe it was in my efforts to isolate the problem like turning on the car with the HV safety plug/fuse removed, or with the HV Safety plug/fuse in but the battery not connected to the engine). But I was starting to have my ODB scanner not report the codes right away when the Red Triangle, Engine Check & HV System Warning Light was on.

Now I have the Red Triangle, the Check Engine Light (and some other lights) on the multi-function display screen and the HV System Warning Light on the display screen, but the ODB Scanner gives no codes.

I found the Diagnostic mode screen and that gave error codes, cleared those and none came back but all the warning lights remain. When I clear the codes with the Torque app talking Blue Tooth to the Bluetooth enable ODB plug the codes go away briefly but then it says problem; the HV system warning Light comes on; it says Problem again and the HV System warning light comes on.

Turning the Car on the car beeps 5 times slow, and 2 times faster. The Car does not move. The Gas engine does not start. Using the Torque App the HV Engine reports State of Charge (was 45% now 39%) and max pair of cell as 15.8V, and the lowest at 15.5V so the HV ECU seems to be talking just fine over the Bluetooth ODB plug.

During this process put in a new 12V battery, so that has a charger hooked to it measuring above 12.4 volts, well above until start putting some load on it.

Was about to go to Harbor Freight and get a real ODB code reader but by the time decided to try that I could not get there before they were going to close, and I am unsure if I don’t get the Toyota ODB scanner if I will get anymore codes then the current ultra-cheap ODB Bluetooth plug.

Any suggestion or advice would be appreciated before I am forced to take this to the dealer and spend money I was wanting to be saving.

Rich

 

Yes that is funny in retrospect. An ODB reader from Harbor freight is more real then a $6 ODB Bluetooth plug. Did try it and will be returning it, 20% restock fee so a $16 experiment. What is a good code reader that will read codes from a Prius?

 

I did look at the connector this morning on my way out and they seem fine, but I want to check connectivity of the wire at both ends of the harness, will have to figure out where those three wires terminate and test continuity.

 

Eric thanks for the reply. When you say know good computer do you mean the HV ECM?