Accident and HV Traction Battery Failure

As I was backing into a Handicapped parking spot my 2002 Prius was hit by another driver trying to take the same spot. The other car hit me on the Driver's side rear bumper wrap and pushed in the wrap on the corner. Other than that, there was no other damage I could see to my car, or the other car. We both agreed to no-damage-no-foul and went our separate ways.

The trip home was one mile. Driving only a half mile from the scene of the accident warning lights came on as well as a check engine light. I thought that was odd.

When I got home I got took out my Denso Hand Held Toyota scanner and checked for problems. There was no code set, only an “impending problem” showing on the scanner. I rest the DTC to be safe, removed and reinstalled the voltage from the 12 starting battery. Then I dorve the Prius, it drove fine for about 4 miles and failed again. Again the same error and cleared with the same process.

I had to pay more attention to repairing the wife’s 2005 Prius, it died within 45 minutes of my car. In the two weeks from diagnosis to receiving parts for the 2005, I limped the 2002 along. With each trip, the error would come on sooner. Finally, the day that I fixed the 2005 Prius the 2002 finely set an DTC that could be read by the scanner. High Voltage Traction battery, Block 8, was showing low by about a volt.

Sure enough, after I removed the HV battery I was able to measure the block voltage. One module was indeed a volt low. I took a spare module I’d had sitting on the shelf for a couple of years and replaced the low voltage module. That fixed the problem.

I’m thinking that when the car was hit it jolted the HV battery and this module was compromised and finally gave up the ghost.

Has anyone else seen this kind of failure after an accident?

 

Brian. thanks for the reply. I'd pulled the battery out and cleaned the buss plates and battery modules of corrosion about five months ago. I have often wondered just how much the salt air does affect the longevity of the HV battery. When I refurbished the bus bars and battery sense harness and bars I also packed the assemblies with Petroleum Jelly to keep the corrosion at a minimum. I am happy to say that when I did the tear-down that there was no corrosion build up.


However, on the 2005 Prius I lost the sense harness and HV Battery ECU to corrosion. It had gotten so bad that the corrosion had followed one pin to the Printed Circuit Board. When I tried to clean it off I found that the corrosion had actually eaten through the pin making an open circuit. I had a complete used HV battery assembly I'd bought a few years ago sitting on the shelf and took it down, hoping to use its parts. It had the exact same problem, except the pin was not eaten in half.


From what I've seen since I saw this problem, it's pretty common on Gen 2 Prii, and on some Gen 1 Prii. I looked at my spare and both the sense harness and the ECU are intact. But it's a puzzling problem.


I'm thinking that that one cell in the 2002 took the hit and it destroyed one of the module's internal sections. I have a SuperMate DC6 that I'm going to attach to the module to see if it can be recovered. I doubt it, but it's worth a try.


Used Gen 2 batteries are getting reasonable enough to buy. I may soon buy another one and start switching the 2002's modules out for the Gen 2 modules.