Master Warning, ABS, (!), and Hybrid Vehicle Warning icon

We're currently in Green Valley, AZ; south of Tucson. Drove ~500 miles yesterday from OC in the 2004 w/76K miles, no problem. Today we drove up to 5,400 ft elevation. On the way down, the Master Warning light, ABS light, (!) brake light, and hybrid vehicle icon in the MFD all appeared. The brightness of the instrument panel and MFD illumination dropped down to the level when headlights are turned on, although the headlights were off.

I have no tools or test equipment in the car. After some thinking, I decided to drive to the Toyota dealer ~30 miles away (Precision Toyota.) The traction battery SOC started at 7 green bars and dropped down to 5 blue bars during this drive. The traction battery fan was on at high speed. The MFD showed arrows when power flowed from the gasoline engine to the wheels. However it did not show any regen arrows nor did it show power flowing to or from the battery.

The driveability was impaired because the engine ran at all times and acceleration was very slow, so I had to get out of the way of traffic behind me from time to time. I did manage to get up to ~65 mph while on I-19 (speed limit is 75 mph.) Then we had to go through I-10 which has several Tucson city exits blocked. Then it turned out the Magellan GPS had the wrong address for the Toyota dealer so I had to call the dealer receptionist to get the right address. However we finally got there, dropped off the car, and rented a Yaris.

My usual guesses as to the root cause would be an inverter coolant pump failure or a traction battery failure. However since I was able to drive an extended distance without the car shutting down, I think the inverter was running at least well enough to keep the 12V bus alive. The battery SOC was not jumping up & down wildly, so that causes me to rule out a battery failure.

I am now thinking that maybe the inverter has a weird problem that does not impact the DC to DC converter, or the hybrid vehicle ECU has a problem. Anyone have other guesses, please chime in.

I hope to hear from the service writer tomorrow regarding diagnosis, etc.

 

Thanks for the comments.

No Scan Gauge, as I question its ability to retrieve DTC generated by ECUs other than the engine. Jay suggested trying to retrieve blink codes; however I believe that is limited to a very small subset of DTC. In any event the car is now at the Tucson dealer and I haven't yet received a diagnosis.

The 12V battery is original. No problem starting the car, the warning lights came on ~20 minutes after we started our descent from Madera Canyon (a very nice hiking and birding spot, BTW.) I was using D until I saw eight green bars on the traction battery SOC display, then moved to B. Once the road became less steep then I returned to D.

The battery fan was running much more than normal. I had the A/C running, trying to keep the battery cool. Ambient temps in the high 90s F.

We are planning to proceed on to Sedona tomorrow with or without the Prius. If the car isn't repaired then I'll have to return to Tucson next week if/when it is repaired...

 

My Prius is back in service now. DTC P3000, info code 603. I don't have access to the repair manual right now (as the computer that I am borrowing does not allow multiple browser windows to be open) so if someone wants to look that up and comment, that would be nice. Apparently that DTC has to do with the battery control system. The solution was to clear codes and download firmware for the HV and engine ECUs per SSC50P.

What is interesting is that SSC had previously been performed back when my dad owned the car. I had driven >60K miles since buying the car with 15K miles in late 2006 and had no driveability problems until now. I'm not confident that this will be a permanent fix but have driven the car ~300 miles so far without further incident - except that the traction battery SOC gauge seems to show 2 red bars more frequently than I would expect during normal driving. So we'll see.

In Hawaii, Servco Pacific is the distributor and that entity does not share vehicle repair info with TMS USA. Therefore TMS USA had no record that the three applicable SSCs had been performed on my vehicle. According to an email that I received from Servco Pacific back in Nov. 2006 when I asked about the SSCs, they were performed as follows:

40L stop light switch April 2005
50P ECU reprogram March 2006
60C intermediate steering shaft July 2006

The Tucson dealer re-performed all three. Apparently inspection of the old steering shaft was inconclusive as to whether it was original or not.

 

Hi Jason,

Thanks for posting the repair manual pages. Looks like the battery ECU is suspect if the code reappears. This morning the SOC gauge started at 2 red bars so I'll keep an eye on that as we drive around today.

Hi Shawn,

The battery vent is clear. I believe there are four thermistors that track battery temp, spaced throughout the battery modules.