Gen 1 2002 CEL OBDII Code P1636 HV ECU Malfunction

The big problem is you'll need a Prius-aware scanner. Check the Stickies and use the search function where we pretty well beat that horse to death.

Bob Wilson

 

Hi Jim,

Given what you have posted, your plan to replace the HV ECU is reasonable. It is located on the floor, front passenger side, and if the car had been flooded in the past the electrical connections may have been compromised. You may want to physically inspect the ECU and remove/replace the connectors, using electrical contact cleaner spray as necessary. That may help the original HV ECU to perform correctly.

As Bob Wilson suggested, your best bet is to get Mini VCI to ensure you are aware of all logged DTC. This will also allow you to reset existing DTC and establish the immobilizer ECU to HV ECU communications, without using the jumper on pins 4 - 13 of the OBD-II connector. Consult techinfo.toyota.com for the particulars involved in replacing the HV ECU and establishing the comm to the immobilizer ECU.

 

It is good you felt insecure, because pin 5 is not the correct pin to use.

Good for you. I suggest you fully-charge the 12V battery now since it was drained considerably after the car was left for 30 minutes or more in IG-ON mode.

 

With the Prius, it doesn't matter how fast or how slow you drive the car from the point of view of the 12V battery. What matters is that the car remain READY for an extended period if you expect to charge the battery while it is installed in the vehicle and you do not wish to use a battery charger. The car could be sitting on your driveway.

It could easily take an overnight interval (8 hours or more) to recharge a serious depleted 12V battery because the DC/DC converter only produces ~13.8V while the optimal charging voltage for an AGM battery is 14.4V or slightly more.

 

Yes, you could.

 

I wouldn't say most based on the 0.3V delta between your high and low voltage blocks. Block 16 is low and may be an indication of a weak module within, but the baseline numbers show nothing of major concern.

You should try this test:

Predictive battery failure analysis for the Prius Hybrid

You can plot several at a time within TIS, or you can export them to excel and plot them all.

Here's where I did my version of the test before and after grid charge/discharge:

Quantitative Results of Grid Charge/Discharge | PriusChat

 

I am hoping @S Keith will add his thoughts but I noticed Google ads for: Prolong Battery Systems. Extending the life of your hybrid. – Hybrid Automotive . My thoughts:

1. Peak charger - incorporates a fan power supply so the excess heat is removed. This is 'less bad' than trying to balance the modules without a fan or on a bench.

But I have issues with their understanding of what is going on. The site claims it is "crystals", a poor understanding of the Prius module failure mode, the loss of water from the electrolyte. I think @S Keith can confirm this as have my experiments. Let's go over what is going.

Over time, Prius modules lose water through parasitic electrolysis with the hydrogen and oxygen gas leaking out the terminal seals. This is accelerated by heat which is a function of driving patterns and climate. This reduces the amp-hour capacity of the module (each module consists of six cells in a shared case.) Since the center modules are hotter than the outer ones, they weaken first:

• Temp 1-3 - from three modules, 1 closest to control electronics, 3 middle module
  
• Temp 4 - air inlet
• Battery Inside Temp - air exit

The middle modules age first and lose capacity. Notice the end modules have the highest voltages while the rest have lost a few volts. The problem pair is #16, well removed from the ends, which has lost capacity.

The voltage imbalance is what happens if you put a "AAA" battery in series with a "D" cell and try to use them in a flashlight with a battery monitor:

1. Both batteries are fully charged to the same voltage and starts fine.
   
2. During discharge, the "AAA" battery, lower capacity, drops its voltage faster than the "D" cell.

The P3006 code means one of your modules has lost capacity and become the "AAA" compared to the others. Grid charging is the same as bringing the "AAA" and "D" cell back to same peak charge voltage. Only when it is back in use, the "AAA" will drop its voltage first and voila, P3006.

There is a mysterious 'balance cycle' that the car can institute on its own. When it happens, power is reduced and the engine runs putting a peak charge on the traction battery. DO NOT SHUTDOWN THE CAR but park and let it run its cycle. It is no worse than using a grid charger and built into the car. Check the 'utilities' in miniVCI and it may be something that can be triggered.

The P3006 is a warning that the pack is weak and needs serious maintenance. You've got a month or so. Your options:

• Grid charging;
  • A temporary patch . . . may buy time.
  • Check 'utilities' with miniVCI and see if you can trigger a balance cycle (cheap!)
• Do it yourself:
  • Single modules - becomes 'whacka mole' so expect to do it again. Almost as much work as rebuilding. Expect a weekend.
    
  • Traction battery rebuild - you'll need 38 balanced modules, Gen 2 or Gen 3 recommended. Takes a week or so of pre-rebuild and then a couple of days to do the swap.
• Warranty covered rebuilder:
  • I used Dorman when they were ReInVolt six years ago, very satisfied.
• Toyota repair, also warranteed.

Fair notice, I'm working on an alternative approach to "warranty covered rebuilder" but it won't be available for a while.

Bob Wilson

 

The P3006 shows a traction battery failure. However, since the voltage readings are fairly constant, if this was my car, I would start by opening up the traction battery case to inspect the condition of the bus bars. If they are found to be heavily corroded, try cleaning them first and retightening the nuts securing the bus bars to the modules. Then see what happens. You have to be very careful with the bus bar that has the very thin voltage sensing wires, to ensure the wires are not damaged.

OP says this is his mother-in-law's car. Hence, he needs to be very careful with the repair approach. IMO he does not want to do the individual module repair approach or trying to rejuvenate a 14 year old battery with a charger. Neither approach is going to offer long term results and he'll have to face his wife and mother-in-law when the Prius inevitably has a recurrence of the problem. Who needs that drama.

I would also be skeptical of "remanufactured" batteries as recent postings have shown many problems stemming from fly-by-night suppliers.

Who is going to be funding the repairs? If the mother-in-law can afford $2,500 for a new battery, then I would say have her purchase it and if the OP can install it, he will be the hero.

If the OP has to fund the repairs, then this could be the MIL's Christmas gift.

 

If you've learned anything about me by now, Bob, it's that it takes almost no prodding to get me to comment...

Coming from the Honda IMA community, I've been familiar with grid charging for over a year, and HA is the primary supplier of grid charging solutions. I didn't get confirmation from hm personally, but I believe he states it in such a manner as to appeal to the somewhat more common understanding about why most people believe NiCd batteries fail, rather than explaining the whole concept of voltage depression. This is my opinion about his website content, not fact. However, I can say with 100% confidence that he understands the phenomena and the mechanics of what transpires during grid charging/discharging based on his posts on Insight Central and his understanding of Mike Dabrowski's work (pioneer of IMA battery work, http://99mpg.com).

Due to the more isolated nature of the IMA modules, and more aggressive use of the capacity range, imbalance occurs more rapidly. Grid charging has been shown to be a corrective and preventative measure for a lot of folks in the IMA world, myself included. It is not uncommon for folks to get another 1-2 years of very useful life out of an ailing pack with somewhat routine grid charging/discharging.

Your comments concerning hydrogen/oxygen loss through the terminals is new information for me (although you may have mentioned it before). It sounds like a very plausible explanation.

My understanding of the progressive deterioration of modules is the onset of voltage depression where consistent short cycling create an accumulation of the lower potential H2Ni2O3 at the terminal. Total capacity isn't reduced, but the capacity is delivered at a lower voltage (depressed). The act of cycling dips into this well of lower voltage capacity and consumed it - a little bit with each cycle. Where long slow deep discharges consume it all at once resulting in a near complete recovery of capacity up to a point.

The fact that one can't always get back to 100% rated capacity is likely the normal deterioration due to cycling as well as your gas loss through the terminals.

Steve

 

Can't mix. They are different lengths and they have different internal resistance that can be problematic.

Your plan is valid, but you will likely repeat the exercise multiple times unless you recondition the remaining modules.

Rearranging modules for the reasons you state is a valid approach, but sorting them on the basis of voltage isn't a reliable indicator of strong vs. weak. You will probably get numbers like this guy:

Red triangle and hybrid warning light, and Check engine light illuminated! Please help! | Page 9 | PriusChat

The bulk will be so close to each other, sorting will be meaningless.

NiMH deliver the bulk of their current at a relatively constant voltage. Thus, their open circuit voltage is a very poor indicator of SoC or capacity remaining.

You'll probably have a few that are notably lower, another group a little bit lower and then the main group that are all very close. It's probably worth your while to replace both of the lower groups. I find this easiest to process if I plot the voltages on a bar charge and do it visually.

But before you do ANY of this, you need to do the load test and plot the block responses. This is an EXTREMELY reliable way of identifying the blocks containing the weak modules. Blocks are numbered from the electronics end.

Steve

 

. . .. Heck we bought the replacement battery over 2 years ago. :-(

The 12V, right? They are dang expensive.

Plan:

1. Remove, HV battery (remove the "don't kill yourself fuse" first) and take a DVM voltage reading on all cells and see if the new old battery had any replacements cells

We call it the 'interlock' plug but it is the same idea. Be careful about the connectors; have lots of plastic/paper cups to hold the fasteners, and; a helper because it is dang heavy. Hand cart too.

2. Order new old modules with 7.5+ volts from fleabay. Anyone had good or bad experiences with any of the sellers there?

Contact me when you get some metrics. However, you may want to order the buss bar assembly versus trying to clean the old one . . . Good, Fast, Cheap, pick two. Safety, remove the two buss bar assemblies first as this eliminates the shock hazard. Take pictures as you do the work to document what you're doing. Lots of cups, again, use a marker to identify where they came from. Modules are numbered 1-38 from the control electronics.

3. Install and hope for the best.

Is heavy with lots of steps but not that hard. Careful with the torque on the terminal nuts. We had one member who didn't and still had problem because the buss bars were not firmly bolted.

Can I mix Gen 1 with Gen 2, I assume no but thought I would ask.

The terminals are slightly offset and the buss bar sections are solid copper. When replacing all 38 with Gen 2/Gen 3 modules, the case has to be modified.

I was thinking since I will have the battery out, I want to re-sort the cells to help them deteriorate more evenly, I was thinking , should I put the healthier ones with the higher voltage in the center and work outward on each side with the weaker cells? i.e. 7.5, 7.5, 7.5,...8.0, 8.0, 8.0,...7.5, 7.5, 7.5?

Correct!

Before starting the repair, please use your miniVCI to do a 'forced charge', snapshot the module voltages, and 'reverse discharge', snapshot the module voltages:

• Drive the car and park it so the rear wheels are against a curb or concrete parking curb. It is critical the car not be able to climb it during the controlled discharge. Set up the miniVCI to measure the battery metrics. You may want to use a 12V inverter to supply power to the laptop/computer since this takes about an hour.
• Snapshot the starting battery temperature and voltages. Using the data editor, select the current, total voltage, five temperatures and 19 module voltage pairs and start recording the data. Instead of all 19 module pair voltages, the highest and lowest module voltages and identifiers are enough BUT you won't be able to identify the second or third weakest module pairs.
• Set the parking brake and with the car either in "P" or "D" and holding the brake, floor the accelerator. Monitor the battery temperature and voltages. The engine will automatically stop running when the traction battery is fully charged, 80%. Recording may reach a limit, follow the prompts and resume recording. You will need this record later to see how the module voltages change over time.
• Step out of car and if battery fan is running, leave the car in READY and take a 5-10 min break; clear the code, and; then resume saving the data.
• Put the car in "R" and monitor the traction battery SOC. This discharge is the most important because it helps identify the weakest and strongest pairs.
• Go home and export the data as CSV (and share with us?)

The weakest module pairs will have the fastest rates of voltage increase during the charge cycle and will also have the fastest rates of voltage decrease during the discharge. The total pack capacity can be calculated on the discharge by using the current times the time (i.e., Amp-Hour) divided by the %SOC change.

Bob Wilson