A Sick 2001 Prius

Ask the service writer how much it would cost to get: (1) all codes read out, and (2) all battery assembly voltages and temperatures. If it is say $100, have them dump everything and then bring them back here. They also have a traction battery, internal resistance measurement procedure but that would probably cost extra for the technician time.

Bob Wilson

 

It sounds like your car has several problems, and the best approach would be to have all DTC read so that you can see the full extent of the issues that you face. Lacking a list of diagnostic codes, following is my interpretation of your car's symptoms:

Usually the Classic SOC gauge will be at either 50% or 75%. Since you see it dropping down to 25%, this is evidence that the battery is weak. The turtle light may be further evidence to this effect; unless you had put the car under unusual load, like climbing a steep mountain road.

The cold weather starting problem is usually attributed to a downlevel engine ECU (the correct part number is 89661–47054) and sometimes to a bad circuit opening (aka fuel pump) relay or fuel tank (since the fuel pump is within the fuel tank.) TSB EG011-03 is the applicable technical document. The circuit opening relay probably is the relay that the dealer tech wanted to replace. This is located in the relay/fuse box between the inverter and driver's side fender.

The accelerator hesitation problem might be due to bad sensors in the accelerator pedal assembly. The issue is that one or both of the variable resistors in the pedal assembly get dirty and cause electrical noise. To see if this is the problem, when the car is IG-OFF try rapidly depressing and releasing the pedal about 30-40 times in an effort to clean the variable resistors. If this provides a temporary solution to those symptoms, then you know that the pedal assembly needs to be replaced. TSB EG018-02 is applicable to this problem.

Not sure why the air conditioning system is at "half power". Does this mean that the fan speed is reduced; or does it mean that the cold air coming out of the system is now at a higher temperature than before?

If you desire to keep your car long-term, it may be a good idea to repair some of these issues rather than allowing them to accumulate like enemies...

Perhaps you can locate a salvage battery assembly locally or via eBay, if so this will substantially reduce the repair cost of that item as compared to new.

 

Perhaps premature ahead of HV battery testing, but you might contact LKQ Online and all their (salvage vehicle dismantler) competitors for bids. There may not be many available at any moment, and you want all the options known to you.

Also, nothing has been heard from Toyota on the subject of their battery renovating since a news article last September:

Toyota: Reconditioning Can Extend Hybrid Battery Life

You may be just the person to follow up on that possibility. Good Luck!

 

I agree that the time has come to seek dealer tech help.

If the car is reving up more than it should, this implies that the hybrid vehicle ECU is desperately trying to charge up the traction battery. Did you have a chance to notice the reading on the traction battery SOC gauge at that moment? Or perhaps the hybrid vehicle ECU is being flaky and driving the engine ECU to rev up the engine more than normal.

If the fan speed dropped, could it be that the 12V bus voltage has decreased below the nominal 13.8V? At the time that the fan speed drops do you see any warning lights appear? The appearance of the "brake" light might also signify a problem with the 12V bus.

Please update us with the DTCs logged and the diagnosis provided by your dealer's tech. Thanks!

 

You didn't mention either odometer reading or if you ever had the battery-seal TSB completed. That leaves us wondering. And whether or not you ever drove without gas is a big deal, much more common with the Classic than with HSD.

What we do know in general though is that batteries have a shorter life when routinely exposed to very high temperatures. So... thank you in advance for keeping us informed how southern late-life is dealt with.

.

 

I am expecting the diagnostic codes to remove a lot of the mystery. There really are several pages of known DTC and INF codes; the computers are likely to have recorded in fairly specific detail whatever it is they think is going on. Until we have those codes read out by the dealer, it may make more sense to relax, pick up a good book or go see a movie than to try to speculate about causes.

Re: the turtle light, I never had the sense that Toyota was trying to be cagey about what it meant. My owner's manual says (p. 94) "If the light comes on, the power will be limited." I don't think I ever took that to mean *I* should try to limit the power - it means I should drive as if I know I have limited power to use. The light will come on if for any of a variety of reasons (not just battery state of charge) the car is trying to save itself by not allowing high power to flow in motor, inverter, and/or battery circuits. (Don't forget that even simply getting ICE power through to the wheels requires electrical power flowing between MG1 and MG2 via the inverter - the car can't ever pretend it just has gears.)

-Chap

 

Please don't treat this as a list of 'get out of trouble free' things ... just the types of lessons learned that could be involved:

• accelerator pedal "big hand" problem that can be corrected by a $500 pedal replacement (or a more affordable service)
• throttle plate cleaning help with engines that don't start the first time but will on a subsequent attempt
• transaxle oil replacements to reduce rolling resistance and eliminate lost viscosity and remove 'stuff'

We didn't really talk about the traction battery and replacement costs. If the car is doing what you want, you may have to decide between a $4,500 battery replacement or trying to buy a replacement. There is a third option, battery refurbishment, but this is an advanced "do it yourself" technique and not recommended for someone with only one vehicle. To do it right takes about 2-3 weeks (not at one time) but it looks to be a reasonable alternative.

But seriously, get every diagnostic code from the dealer and a battery survey. With knowledge, you can make informed decisions instead of having the decision forced upon you.

Bob Wilson

 

Ah, that'd be Bob Wilson.

He posted a bunch of annotated pics recently in a battery-related thread. A search will probably turn it up.

-Chap

 

There are several approaches depending upon which set of (1) Good, (2) Fast, and (3) Cheap you want follow.

1. Toyota ~$4,500 battery replacement - good and fast
2. Replace with a salvage battery pack - fast and cheap(?)
3. Rebuild or refurbish battery pack - good and cheap

The first is guaranteed and quick. You don't need a work shop or a second commuting car to use during the swap or just rent one for a day.

The second is risky because serviceable salvage battery packs are rare and getting rarer. However, they exists but check Ebay for prices. The risk is the battery pack may also be worn out. Still, you could mix and match the "less bad" modules and get more service life.

The third takes the longest time so you either get a spare pack to refurbish or have a second car to use while you take the 2-3 weeks to refurbish the pack and a reasonable workshop. This remains an experimental process so if you decide to take this approach, you will be broaching new territory. However, I'll share what little I've learned.

The third approach has a variation that is less risky of getting two NHW20 salvage packs and replacing the NHW11 modules from them. This has the advantage of improved modules but disadvantage of cost. But you can resell the excess modules.

But this is all speculation pending a readout on your car's health and status.

Bob Wilson

 

Say Bob,

I seem to recall from the G1 battery restoration thread that you have not yet tested the NHW20 modules for fit in an NHW11 battery case, and that the testing will be nontrivial and require attention to detail. I agree that it sounds like a great idea, but until it has been tested (carefully and with great attention to detail), I'm a little worried about suggesting it to others without mentioning that it hasn't been confirmed to work yet, and that one of the important details needing attention is going to be how much the reduced terminal-to-cover clearance affects risk of arc flash, explosion, electrical burn, caustic chemical burn, blindness, death, and/or decrease of resale value.

I'll be waiting with real interest to hear more about the testing and ideally a confirmation that it works without problems. But I'm pretty sure that ought to be done first by any of the really experienced voltheads on PriusChat, before making that suggestion to a relatively new poster who might be less familiar with the ins and outs of working on the HV system.

Hi gippah,

The thread I linked above is the one where you can find Bob's annotated pics of the process; that should help explain why the refurbishment isn't a quick job.

If there are bad modules, the codes you get from the dealer will include voltage readings every pair of modules and help identify where the bad ones are.

But really, until you get those codes from the dealer, we're still all shooting very much in the dark. Deep wackiness in either the battery ECU or the HV ECU, for example, might be able to produce the symptoms you're describing too.

-Chap

 

I have tried to share everything I know and this includes side-by-side comparison of the NHW20 and NHW11 batteries. I offer the idea with hopefully full disclosure including what has and hasn't been tested. If I didn't have a spare NHW11 pack already, knowing the physical dimensions, I would go with the NHW20 approach. The dimensions are close enough I believe there is no problem.

Bob Wilson

 

Next week when my Prius hits the 100,000-mile mark, I was going to point out my battery status then... but I suppose it would make more sense here & now.

Since my Prius is a HSD, the cells themselves are different as well as the Multi-Display indication of charge-level. But I think this is true nonetheless: SOC goes UP as the miles do.

6 bars used to be rare. I clearly remember "seeing the blues", telling others how long I could go (days at a time) without ever seeing green (7 bars). Now, I see green several time a day. I'm quite convienced that it is the result of vehicle components loosening up over time.

So... you shouldn't see a drop if the battery-pack is still healthy (based on my observations).

.

 

This remains an area of interest and so far, the best protocol I've seen suggested is:

• force charge at the bottom of a hill
• use "reverse" up the hill at a slow speed, <10 mph
• measure change in altitude

I tried it but the cop car made me aborted the test at about 25 m. but it already looked like this hill was too small. There is a larger hill, 160 m., but the summer heat has arrived and I prefer to avoid force-charge, heating of the traction battery.

My static tests suggest the battery capacity may be determined from the internal resistance. However, this remains an area of investigation. But your comment is consistent with higher internal resistance driving up the charge voltage sooner. But these are imprecise terms ... more rule of thumb than a quantifiable number.

Bob Wilson