Replace 2006 batteries, ECU, and/or engine?

I have been having problems for a couple of years now, but my 2006 Prius has sat in the garage now for the past year. I am not sure where to start, but here goes.
My son had been using my Prius for a couple of years, and it now has 175,000 miles on it. He really drove the wheels off that thing.
In July of 2010 he took it to a local Toyota dealership since it has been getting worse gas mileage and the warning light came on from time to time. At that time, the dealer quoted a new drive battery (G9510-47031) for $2589, and a new battery ECU (89890-47092) for $698. But they did not give us any error codes to base their decision on. In addition to that, the rear main seal was leaking, and their quote showed about 15 hours to replace it. Well, I was not about to spend that kind of money on this car (my son left it in pretty bad shape). But after putting it in the garage for a while, and cleaning it up some, and reading more about the Prius on-line, I decided it was time to get it working again.
So, I have been trying different things to it.
I removed the drive battery and cleaned up the jumper bars between bricks, then reinstalled them. They were not in too bad shape, but there was some tarnishing and slight corrosion of the copper bars.
After I reinstalled the drive batteries, I tried it out again. This time I determined that the 12 volt battery was bad (~9 volts), and just replaced it last week. I can see in the side of the battery and can tell that 3 cells are low, but did not want to try to refill them. The battery is 6 years old, so I figured it was about time to be replaced any way. It was getting a P3190 error code prior to working on the batteries. The engine would hardly run. I figured out that the 12 volt batt. was a lot of the problems.
Another item to note. The motor is making a tapping noise, and it sounds like it is coming from the top end area, maybe a lifter. There is only one sound, not many different ones. Upon inspecting the plugs, the #2 plug has oily carbon buildup, but the others look fairly normal. A compression test of each cylinder showed about 110 psig in each one.
I am fairly sure my son let it get too low on oil, and probably damaged the engine some. I believe that's the reason for the tapping.
Due to the tapping sound, the carbon on the plug, and a discoloration inside the valve cover, I put Seafoam in the fuel, sprayed into the throttle body throat while running the engine, and poured about 1/3 bottle in the oil via the oil fill cap. I ran the car about 50 miles, then replaced the oil and filter. I cleared the check engine light and DTC codes.
Since then, I have driven the car about 300 miles. But I am only averaging about 24 mpg (it used to get about 44). I looked at the oil on the dip stick, and it is still very clean. Also, after driving the car 300 miles, the check engine has not come back on. The only light ion the dash it the red SRS alarm showing the SRS is not working. (That is another issue)

The battery indicator never goes above 6 bars, and when running 70 mph, it stays on 1 bar. When driving around town, stopping and starting, the battery gets up to about 4 bars.
The gas engine almost always runs, so I don't know if the gas engine is just not putting out enough power, or if the batteries will not take a good enough charge to allow the electric motor to assist when needed.

As a note on the drive battery, when cleaning it up. I read the voltage of each brick while disconnected from the rest. The voltage was from 7.4 to 7.5 volts using a DMM. I then used a 100 amp, 12 volt battery load, which put 50 amps across each battery individually, and read the voltage across each battery. I was getting from 6.0 to 6.2 volts on each of the 28 bricks. There were none that appeared to be any different to any of the others. After driving around town, I then measured the voltage at the cables coming from the inverter at the relays at the battery. The voltage was about 215 volts. That seems to be enough to keep the batteries charged. I have not read the battery voltage with the engine not running. I will try to do that this week end.

So, what do you think my next step would be.
My engine has the tapping noise, and also a leaking rear main seal.
The drive batteries appear to be weak.

As with anyone, I am not sure how much $ I need to put into this car to get it running reliably and efficiently for the next few years. I have found used engines on the internet for about $500, and if needed, I might attempt that too. Yes, I know the engine has to come out the bottom of the car. I thought about just inspecting the cams and valve train, and maybe replacing the head if needed, but I would still have that rear main seal leak that keeps leaking oil all the time. I enjoy tinkering on and learning more about all cars. Especially on a spare high tech one, like this one currently is.
I am not an expert mechanic by any means, but I will attempt to repair almost anything, and eventually have success at it. My motto has always been that I would much rather buy new tools and learn how to do the repair myself than to throw away my money at the dealership or repair shop. I just don't trust those guys.

Thanks for any feedback and help anyone can provide,

 

Does this mean that Re-involt cannot repair the batteries? (in case I cannot find any at a junk yard)


Why does the battery ECU need to be replaced, typically. What happens to it that might cause it to go bad? Could it be bad, causing the batteries to appear bad when they really are still good?

 

Well, I am really confused now. Took my Prius to our local Toyota dealership on Friday. They say there is nothing wrong with the drive batteries. I got the printout from their battery test, and it shows each battery block (2 batteries/block) were from 15.1 to 15.29 volts. The only DTC codes they found in the ECU were due to the SRS system, which they corrected by 'calibration'. But 1-1/2 years ago, this same dealership said I needed a new drive battery and ECU.

They said I did need a new ICE, as I figured, due to the knocking sound. I was hoping they could at least find what part of the engine the know was coming from, so I could decide what to do next. Replace the entire engine, or rework the head. Not that I would buy it, but a new Prius gen II ICE was quoted at $8000. Wow! Used ones online are $500.


Could the battery ECU be the problem? I just don't think I should have only 1 bar on the battery monitor when traveling at 70 mph, nor should I be getting 24 mpg. The ICE seems to have plenty of power, so I wouldn't think it would cause the low mpg. My tire pressure is 40 on each tire.


Any suggestions?

 

Replacing 2006 engine

Ok, one thing at a time. I will replace the engine first, then go from there. I picked up a used 2007 Yaris 1.5L engine at a junk yard. It supposedly had 39k miles on it. Is supposed to be the same engine, but there are some differences. I know for sure the intake manifold and throttle body are different, so I will reuse my old one. The rear main seal had some oil around it, so I will replace it while I can easily access it. The radiator fluid was a burnt orange color in my car. Is that the normal color. I also drained the coolant from the inverter, and it was a clean pink color. I assume that is the correct color for it. I will drain the transaxle fluid, and replace it as well. What else should I be doing while replacing the engine and can access everything?
Will keep you updated on the progress. I am taking pictures of the disassembly, so if anyone needs any special pictures, let me know and I will be glad to help others as I am learning myself.

 

Thanks for the advice on returning the engine.
Before I read your reply, I had already read up on it, I discovered I got the wrong engine. So I will return it and get the correct engine. Sure is a good thing I did not install it. I would have been really PO'd at them and at myself for making such a dumb mistake.
But that is why I am chatting on this forum.

Thanks again Patrick

 

Progress update on swapping my Gen II engine.I am almost finished with the swap. The used Engine has been attached back to the electric motor/transmission. The assembly has been raised back into the engine compartment and fit back up to the mounts and bolted up. All of the wiring harness connectors have been reconnected. The hoses are reconnected. Next I will reinstall the convertor/inverter and complete the hoses and wiring back to it.
I'm waiting for CV joint clamps and an installation tool so I can begin putting the axles back in and then reinstall the subframe and then reconnect the front suspension. Then reinstall the steering wheel and clock spring (some controls were not working on the steering wheel, so I took it apart to test).
Then refill all the fluids (coolant, oil, transmission fluid).
It has been a weekend project that has lasted a couple of months. I almost gave up a couple of times, but after reading these forums and gaining confidence and knowledge, I continued on and here I am. I am proud to say that I have done the whole job by myself. This is my 2nd engine swap, and my first on a Prius. I will add that I will never do a Prius again. I did the work myself to gain knowledge and skills. I will try anything once.
I have taken many photos and short video clips in case anyone needs some help with their repairs.
Hopefully, this upcoming week will be the final steps in this huge project I have undertaken.
Then, if it works, I can find out how the drive batteries are doing, and then maybe work on it's replacement.

 

Was a good weekend. Got the salvaged replacement ICE running. Now I can go back and tighten the front suspension and finish adding fluids. All that is left is finishing!
Radiator refilling is a very slow process. Maybe the overfow reservoir will get sucked into the engine tonight as it cools down.
Inverter seems to be almost full, but still gurgling some. I bled the air from the top bleed valve till no more came out.
Wasted time reconnecting the steering u-joint since I found a missing clip after the steering rack and pinion was installed. But finally figured it out and reinstalled the steering wheel, clock spring, and air bag, before I reconnected the batteries.
Without driving the car, it seems ok, with no check engine light on. But I am sure the HV battery will need to be replaced. Just need to drive it som and confirm.
Will work on it this week, and should get it drivable soon.

 

Prius is running very good, now. Even passed state inspection today.
MFD is showing about 36 mpg.
A lot better than the 24 I was getting before replacing the ICE. I know my drive batteries are supposed to be getting bad from previous tests that were done, but I am not so sure now.
So my question is.
Do i replace the HV battery now or wait until the mileage drops more.
This weekend was the first time in a long time I had seen the battery condition bar graph up to 9 bars, and green!
I still need to have the front end alignment checked since I had it all taken apart to replace the engine. Maybe that may help the mpg a little more.
My local salvage yard can get me a used battery set for $500, condition unknown.

I am now also working on my steering wheel control buttons. Most of them don't work. After I disassembled the steering wheel and got down to the actual switches for the buttons, I discovered that the printed circuit board that the switches mount to, was broken in half. Guess my son really beat on that horn really, really hard a couple of years ago. The dealership was supposed to have repaired it, though.
Now I get to go back to the salvage yard and get a steering wheel, to get the controls working gain. I could possibly resolder and repair the old board, but it probably wouldn't last. My eye sight and soldering skills aren't what they used to be.

 

I put about 120 miles on it since the engine swap. Each time I disconnect the batteries, though, I loose my mpg.

My mistake. I thought there were 10 bars on the display, but now I know there are only 8. So it was only showing 7 bars. Still best I have seen in a long time.

Got a replacement steering wheel today and installed it. Now all of the steering wheel controls work. Just gave back the clock spring I didn't need, and got a steering wheel from a wrecked 2009. Only $75.

Forgot to tell the guy at the salvage yard that I don't need the HV battery at this time. Better do that tomorrow.
Guess I will put all the battery covers, rear seats, etc. back in the car and finish this project.
It's good to have multiple salvage yards within 5 miles of home. They are becoming one of my favorite places to go.