Hybrid Battery Ecu

[mfs1011]

Greetings everyone.

My 07 Gen2 has developing hybrid Battery ecu issues with and I wonder whether anyone has experience of sourcing and replacing this part?

My dealer is willing to install a second hand part as a new one would cost in excess of £800.

I've found a part on eBay from the US (as you do) but the only niggle is that the part number has an extra zero on the end.

The dealer has given me part 89890-4709 and the listing on eBay has an extra 0 on the end.

If I spring for this part, am I likely to find some incompatibility between the US and UK models?

Thanks for all your wisdom and advice in advance...

[Grumpy Cabbie]

Trusting you've checked your 12v first?

To reiterate for those who are new and those who may not know, but the 12v in the Prius is a weak spot and generally lasts about 5 years or so. Some get a little bit more. If the 12v fails it's not like you'll notice in a traditional car where the car will turn over slower and slower over a number of days. With a Prius it either has enough power to boot the computers or it doesn't. If it doesn't you get all manner of weird and wonderful error messages. One of the popular issues is the central locking goes to pot but also a common error for a failing 12v is the HV Battery ecu.

Don't rely on the dealer telling you the 12v is ok. It's renowned that they're wrong here as they rely on their computer too much. Test your 12v after it's been sat overnight, put the car in ACC (not Ready) and then wind all the windows up and down at the same time. If they're super quick and smoothly glide up and down no bother, then your 12v is fine. If they're super slower, judder and your interior lights go dull or go out, then you need a new 12v.

As it's £95 fitted, it's a cheap fix to many many Prius problems.

Alternatively, if you've done that and the 12v is fine, then you probably need a new ECU.

If that's the case, is your car still in warranty? Does the hybrid ECU fall under the hybrid warranty?

Failing that, whilst the EU and US Prii are very similar in the gen3, the gen2 did have more differences; the US cars having rear drum brakes with EU spec cars having discs. There are also suspension differences too. Regarding the ecu's, that's a good question. Are you feeling lucky? If it works, then you've saved yourself a load of money. If it doesn't you could always stick it back on eBay. I do wonder if the extra 0 is just because of differences in parts computers?

P.s., I've had my HV Battery ecu replaced at least once and possibly twice, thankfully under warranty, so you're not alone with this problem. Did you notice a weird cycling of the HV Battery before? Did the car seem to get confused over what the HV battery levels were, running the engine continuously etc? Did the HV battery sit at 2/3's instead of 3/4's? Has the car been parked for a while of late, such as in an airport carpark (12v run low)?

[mfs1011]

Hi Grumpie Cabbie

Thanks for your suggestions.

Yes the 12v did figure in my thoughts and I did check the voltage in maintenance mode using the screen hack. Suffice it to say there is tell tale evidence of 12v issues, but nothing conclusive, hence I have to consider other causes and pay heed to what the Snows Toyota man and his diagnostics tell me.

Fixing PCs for a living as I do at the moment, power issues present in a number of ways so yes, replacing the 12v is still an option. That said ecus do go wrong.

It's slightly frustrating when you ask the man with the gizmo just what has failed in the ECU and he replies 'computer says no'.

Just a thought, is it possible to reflash the firmware in these cars?

Finally, goods to see you still around on this forum Grumpie Cabbie. I bought my Gen 2 in 2009 and have racked up a fair few miles. It's been a quite reliable car - what are your thoughts on longevity over 150,000 miles?

[Parts-King]

You have taken the part number down incorrectly, the Toyota part numbers are ten digit

April 2007 to 2009 production cars have 89890-47092 fitted to them

89890-47090 has been superceeded to -47092, so if you bought that one, it would not be modified like -47092 is, so you could have the same problem in the near future

Kingo

[Grumpy Cabbie]

Finally, goods to see you still around on this forum Grumpie Cabbie. I bought my Gen 2 in 2009 and have racked up a fair few miles. It's been a quite reliable car - what are your thoughts on longevity over 150,000 miles?

A gen2 is almost (and not literally) bomb proof. They are over engineered and there are reports from the US of them being run well over 400k miles.

The gen3 is another kettle of fish and would appear to be weaker (smaller, lighter parts under higher stress). Thankfully I'm no longer in the cab game and Toyota have the unlimited mileage, 10 year hybrid warranty so long as you get the car serviced at Toyota or pay your £40 every 12months/10k miles.

So with hindsight it appears you have the best Prius yet. It should serve you fine and few issues. You have one of the last made so has all the issues ironed out. The early gen3 should have got my alarm bells ringing when the warranty was reduced to 5yrs/60k miles for the hybrid side. Sure the extended warranty has been introduced since, but makes me wonder if Toyota knew something. I'm on my 3rd steering motor, 2nd inverter, had 1 or 2 hv Battery ecu's, an egr valve replaced at £400+ and my mileage is only 80,500 today. The gen3, or at least the early ones are weak to put it bluntly. :(

[Carltona123]

Is there any chance you could borrow a good 12v and try that?

There's one sitting in my garage which you'd be welcome to try.

I live just south of B'ham - any good?

[Carltona123]

What about trying some of the breakers on eBay UK?

[mfs1011]

Thanks for all the help. I'm going to replace the Battery and see if that sorts matters.

[mfs1011]

Just a follow up to the conclusion of this saga on this thread