P3009 HV leak detected with no other codes. Is this the end of the road?

Does your Innova 340c allow you to monitor battery temperatures? If it still drives normally, my main concern with continuing to drive it would be that at some point the battery may overheat to the point that it might possibly ignite. I guess you would also want to be careful about touching anything metal close to the battery, if there really is a HV leak. Otherwise, I would continue to drive the car, but keep an eye out for its replacement sometime in the near future.

 

52 to 54 degrees C sounds uncomfortably high. Best not to drive it in that condition then. You haven't mentioned how many miles are on the odometer, but the age in years argues against repairing it. If you didn't have to replace the entire battery, you or your mechanic would have to spend considerable time trying to track down the leak, and it wouldn't be advisable to just replace a few modules and leave the rest, as old as they are, anyway. As you suggested, it might be the end of the road.

 

I see a sticky by Draco about MG2 replacement, but nothing about his battery. The general consensus on the Gen 2, Gen 3 batteries seems to be that they normally operate in the range of 35 to 40 degrees C, 95 to 104 F, for maximum efficiency. The middle sensor on mine was reading 58.4 C on a trip to Vegas last summer and it survived that, so these batteries are at least somewhat heat tolerant, but if you see temperatures above 45 C regularly, there is something wrong. Gen 1 uses the same chemistry as Gen 2 and 3, so I cannot believe that the temps are as low as you say.

If you really want to keep the car, according to this thread, https://priuschat.com/threads/replace-gen-1-with-gen-2-battery.147122, you can replace your old modules with new ones that are part of the Gen 2 pack that Toyota sells, but it looks like you would have to buy 2 new packs, since the Gen 1 battery contains 38 modules instead of 28. That hardly seems like it would be worth it. I'm afraid there are no good options to keep a Gen 1 car on the road once its HV battery fails, unless you can luck into a pack with new modules at a wrecking yard.

 

Gen 1 modules are well known for having some minor leakage from the terminal studs. Most likely, this leakage has gotten to the point where some liquid has reached the battery case and resulted in your code. Many of these batteries were "sealed" on a recall, where sticky/gooey sealant was applied to the terminals to prevent/minimize leakage. I've seen some batteries that never had the recall performed. I wonder if it is still an active recall?

Anyway, if the battery is performing fine in all other aspects except the voltage isolation, a good cleaning on the sides of the modules would probably solve the issue.

 

Karen, you seem to be quite apt. You can clean individual module and replace the buss bars and it will probably solve your "leakage". Corrosion increases resistance and makes voltage loss more likely. If the buss bar connections are good, that will reduce that as a potential problem

My previous Gen 1 in Tucson, died at the airport. The previous owner did a comprehensive buss bar cleaning and the codes and problems went away. BTW, you can do this all without removing either the whole battery or the individual modules. A lot of bending and discomfort, but do-able.

 

Toyota Hybrids P3009: High Voltage Leak Detected, internal to battery - Luscious Garage | Hybrid Specialists

 

Lets start here! Empty the trunk of all objects except OEM installed equipment. Examine trunk mats and side covers for moisture. Raise trunk mats and check for additional moisture. Also examine 12V battery area and underneath battery. Any evidence of moisture and you are on the trail. Clean all trunk areas of any moisture found and attempt to air and dry out all areas. If moisture found, you must find areas of leakage. Also review some of my post related to this problem. Been through this and, at least for now have solved the issue. Once you have found the source of the moisture (trunk seal, areas around the top corners of the trunk where the welds meet etc), you can then fix the issues.I have dealt with this twice, but since I have closed the defects, no issues. Post back if you need so assistance. Even if you must service the HV battery (clean contacts), its doable. Except for the cost of a role of silver aluminum duct tape and some clear silicon, all the rest was my labor. My HV had been serviced in '05 by dealer for the sealer on the terminals and it took a small amount of time to clean, along with removing the corrosion from the post and post connectors, but all is not difficult just takes time. Hope this helps. Again, post if you need help. Peace

 

I did mine about a month and a half ago (mid-September 2018), in my driveway, without taking the traction battery out of the car. Working on the back side of the battery, inside the trunk, does have you standing behind the car and bending over inside the trunk for a while, but it's doable.

One thing I should add: if you don't have any scary lights on the dash or the touch screen (!-triangle, !-car, PS, MAIN, Check Engine) right now, then you may not have anything to worry about. Prius has a long memory.

Story time: The brake fluid level in the reservoir on my '01 was very gradually dropping - we are talking over years, here - as the brake pads and shoes wore down, which is totally normal. It was getting close to, but still above, the "min" line molded into the reservoir. One day in 2017, I was driving it around, and had to go up a pretty big hill. The red "BRAKE" light on the dash came on. I pulled over, checked to make sure the parking brake was off, and tried the brakes a few times on the side of the road, and they seemed to be OK. I drove (carefully) about another mile and a half to a gas station. At the gas station, I bought a bottle of brake fluid and refilled the reservoir. That made the car happy and the BRAKE light hasn't come on again since.

Almost two months ago - around a year after the BRAKE light - I was working on the car for another reason, and had my first experience with Techstream, Toyota's scan tool. I had used another scan tool on the car, but it couldn't see as much as Techstream does. When I first hooked it up to the car, it showed the C1202 code set - "low brake fluid or brake fluid level switch open circuit". It remembered my sins from a year ago! I cleared that code and it hasn't come back yet.

The original traction battery in my '01 had that recall done at the dealer. The way you could tell: there was a square of thin black foam underneath one terminal on each module, and the module terminals and nuts had been "painted" with rosin... imagine really thick paint, clear to slightly brownish, to get the idea. When I had to undo the nuts, it took maybe a little extra effort to get them loose, but I could do it with a standard ratchet wrench. The rosin also caused the bus bar modules (orange plastic around the bus bars) and service plug cable ends to stick to the modules... the solution there is to just keep pulling, firmly but gently. The rosin will eventually give up and you can get the thing you're pulling on free from the modules.

I replaced the entire traction battery in 2010 when a few of the modules in the original battery failed (very low voltage, not P3009). The replacement battery didn't have the black foam squares on it, but it did have all the factory-installed module nuts painted with rosin. That didn't cause any problems when I installed the battery. A couple of months ago, I started getting the P3009. When I took the traction battery apart in an attempt to fix that, I had to use maybe a little more force on the ratchet, and sometimes I had to pull on things for a while to get the rosin to turn loose, but eventually I got everything apart.

The leakage caused by the corrosion is a very much smaller current than the traction battery provides or accepts in normal driving. The leakage current is hard to test directly while you're driving around, but the directions for testing it with the car parked in the service manual imply that it needs to be 0.05 milliamps or less, which is equal to 0.00005 amps or less. In normal operation, the traction battery can provide or accept up to about 100 amps - that's when you're driving either up or down Pike's Peak. Even if you're backing out of a driveway at 3 or 4 mph, using 5 horsepower from the electric motor only, you're still pulling roughly 14 amps from the traction battery.

In other words, you can have enough current leaking to set off P3009, without measurably changing the voltage of an individual module.

The reason the car cares about the tiny currents caused by corrosion leakage is that the high-voltage DC system "floats" with respect to the car body - the negative side of the traction battery is *not* connected to the body. If everything is 100% working right, none of the high-voltage DC should appear anywhere else in the car. When it does, you get P3009.

This page 2001 Toyota Prius NHW11 battery terminal cleaning shows what the busbars looked like on my car before I cleaned them. This was enough to set P3009. After I cleaned them, I've driven the car about 300 miles and it hasn't come back yet.

Coming next... my version of fixing P3009 by cleaning the bus bars in the traction battery.

 

If you're contemplating cleaning the bus bars inside the traction battery yourself, here is some advice. I am not affiliated with any companies mentioned.

This is based on memory of doing this a couple of times (most recently about six weeks ago), and may be incomplete. I tried to write down everything I can think of, though.

You need a ratchet, an extension or two, and a standard set of metric sockets from 10 mm up to about 19 mm. You won't use all of the sockets in that range but you need at least a few of them.

You also need a Torx bit (six-pointed star), size T30 (I think), to undo one of the screws on the traction battery case. The torque is enough that you may need the kind of bit that plugs onto a ratchet, and not a screwdriver. This is a fairly normal thing that most hardware stores carry these days.

You will probably need a flat-blade screwdriver and maybe some pliers, for things like the plastic pegs that hold in the fuzzy trunk lining.

You may want a torque wrench that can do at least 60 inch-pounds. Note: inch-pounds, not foot-pounds! This is for putting the module terminal nuts back on to the correct torque. You need enough torque to make a good connection, but not so much that you twist the terminal studs out of the modules.

I bought a Sears Craftsman torque wrench back in 2010 when I swapped the traction battery and I used that one. Sears is almost dead, but they may still have a torque wrench that will do this on the shelf. If not, try Lowe's, Home Depot, maybe Ace Hardware, or similar. In my opinion, you don't have to go buy a pro-mechanic brand at pro-mechanic prices (Snap-On, Mac, etc), but this is a spot where I wouldn't trust a Harbor Freight Tools torque wrench.

It may help to have a 10 mm nutdriver. When I took mine apart, I used the ratchet to loosen the module terminal nuts initially (because I needed the leverage). Sometimes I took the nut all the way off with the ratchet, and sometimes I used the nutdriver instead. When I put the nuts back on, I started all of them with the nutdriver, and then finished up with the torque wrench. The nutdriver will usually have a plastic handle, which isn't officially rated for insulation, but it made me feel a little better when working on the module nuts.

You need a small wire brush - the kind that looks like a toothbrush with brass bristles is about right.

You need something to put the individual bus bars on while you're wire-brushing them. Each one is a copper rectangle, about half an inch wide by an inch long, so it's kind of hard to hold one end with your finger while you wire-brush the other end, without also wire-brushing your finger. I used a couple of old pieces of wood (slats from a pallet), which were flat, but rough enough that the bus bar wouldn't slide around too much while I brushed it. I laid the bus bar on the wood, brushed one side, flipped the bus bar over, and brushed the other side.

You may want some kind of mild acid to clean the busbars some more. I used white vinegar from the grocery store. Muriatic acid, sold for cleaning concrete, is probably too strong.

If you use acid, you should follow up by washing the busbars in plain water. I used distilled water because I had some, but tap water would probably also be OK.

If you clean the busbars in acid, you probably want some small plastic containers to hold them. I used some trays that came with frozen dinners, because I had them.

You might want a bunch of Ziploc (or equal) bags and a permanent marker. You have to take out a number of bolts to get to where you are looking at the insides of the battery. If you put each group of bolts in a bag, and then write "seat back bolts" or "battery cover bolts" on the bag... you spend less time wondering how it all goes back together.

You may want a towel, or a chunk of foam, or one of those stadium seat cushions to sit on. I did mine with the bottom cushion of the back seat out of the car... you can sit directly on the sheet metal under the seat, but the towel or foam makes it a little nicer.

You may want a good flashlight (or 120 V light with extension cord) for working in the trunk.

Here goes...

The overall idea is that the top cover of the traction battery is a U-shaped piece of sheet metal, as long as the battery is. You are trying to undo all of the stuff that is attached to this cover, so you can lift it up and work on the inside of the battery.

Park the car somewhere it can sit while you do this whole procedure.

Write down your radio station presets and the mileages on Trip A and Trip B, if you care about them.

In the trunk, disconnect the negative cable to the 12 volt battery. Make sure the cable can't flop over and hit the battery terminal again.

Remove the service plug to the HV battery and stow it somewhere close... you need it again in a minute.

Take out the fuzzy lining in the trunk over the HV battery. You will have to undo several of those plastic pegs for this to happen.

In the back seat, take out the bottom seat cushion. Lift up on the front left corner and front right corner to undo the latches, and then lift the whole front edge of the cushion up (like opening the hood) and pull the "prongs" on the back of the bottom cushion out from behind the back cushion. Feed the seat belt latches through the holes. Stow the bottom cushion somewhere. (I put mine on the roof of the car... you may prefer to put it inside the house.)

You will see three wire loops coming down from the bottom edge of the rear seat cushion, with bolts and a big washer holding them to the body. Take out those three bolts. Next, lift the rear seat cushion straight up to disconnect the hooks on it from the slots in the parcel shelf. Slip the far left and right seat belts over the edge of the cushion, so they land behind it, and pull out the middle seat belt a little... then you can take the cushion out one of the doors and stow it.

There are two metal bars behind where the rear seat cushion was. Undo the four bolts and take them out.

There is a plastic "wall" covering the hole into the trunk. Take it out. (At the bottom, it has plastic pegs into the top of the battery case, which you probably already removed when you took out the fuzzy lining in the trunk.)

On the driver's side, in the back seat, two big orange cables go into a cover with three nuts and an orange plastic button. There is a plastic tab on the service plug that fits this orange button. Use that tab to spin the button counterclockwise (like unscrewing a screw), which should loosen the plastic peg connected to it. Then, take out the three nuts, and take the cover off. You will see that each orange cable is bolted to the battery - take out those two bolts and pull the cables away from the battery.

There are a couple of metal brackets at each end of the battery case; they bolt on to the end of the battery case and to the car body. Undo the bolts and take both of them out.

On the driver's side of the car, the black plastic duct to the battery cooling blower comes down onto the top of the battery case. Undo the four screws into the top of the battery case. Follow the duct up from the battery and you will find a spot where that duct bolts onto the blower motor with two bolts - take them out, and then lay the loose section of duct in the trunk.

In the back seat, go along the lip on the front edge of the battery case and undo the bolts. Most of them are hex-head, but one of them will be the Torx head.

In the trunk, go along the lip on the back edge of the battery case and undo the bolts.

There are a few small bolts along the passenger's edge of the battery case, on the top and sides. Undo these. One of them holds a metal L bracket that is attached to the black plastic duct on that end of the battery. Take out the bolt. You may need to squeeze the duct towards the outside of the car a little when you take off the battery cover, so that L bracket clears the cover.

There is also a white plastic clip over the passenger's edge of the battery case. This is part of the battery vent system. Use a flat-blade screwdriver to pry up the clip, and then push it towards the outside of the car just enough that it slips off of the top of the battery.

I think there are a couple more small bolts on the top of the case on the driver's side, under where the duct you removed was sitting... take those out as well.

Spend a minute going around the case, looking for any other bolts or nuts that you think are holding it on. Remove them if you find them.

Now... lift the cover straight up and off the battery. It is probably easiest to sit in the back seat, put the fingertips of your right hand along the inside edge (towards the middle of the car) of the hole where the duct was, put the fingertips of your left hand along the passenger side edge of the cover, and lift up. Keep lifting until the cover is totally clear of the battery. I think I usually bring the cover into the back seat with me, and then carry it out one of the doors. Stow the cover somewhere clean and dry.

The first part is done. Go get a beverage or something, then go on to part 2.

 

Here is part 2.

The idea, here, is that you need to take out all the nuts for the busbars that connect the battery modules together, then take the busbars off the battery, clean them, put them back on the battery, and put the nuts back.

Take a look at the front and back sides of the battery. You will see some flat black plastic pieces, about 2 inches high - there are four of them, two each on the front and back, each covering half of the length of the battery. Start at one end and gently pull the black plastic piece away from the battery; it's clipped on to the orange thing underneath it. When one is loose, set it down and go on to the next one.

You will now see a bunch of nuts with metal busbars between every pair of nuts, with the metal bar surrounded by an orange plastic rectangle. In the middle of the back side, instead of a metal busbar, there are two cables that go over to the service plug (There is a black plastic insulator around these cable ends - if you unclip the bottom end, it folds up to reveal the cables.) At the far ends of the front side, instead of a metal busbar, there is a cable that goes over to the main relay in the driver's side of the battery.

The orange plastic things help organize the cables, and also hold the busbars. This is so at the battery factory, they don't have to handle a bunch of individual busbars - the busbars are clipped into the orange plastic ahead of time, and then the orange plastic is put down over all of the module terminals at once. There are four orange plastic things total - each one does half the battery on its side.

On the front of the battery, you can also see the small wires to every other nut, which join into a bundle going over to the battery computer. This is how the battery computer knows the voltages of every two modules along the string. The ends of these wires have a square flat terminal, with a hole in it, that goes on top of one end of a bus bar.

The first thing to do is to start disconnecting nuts. I like to do the two on the service plug cables (middle of the back side) first, and then the two on the main cables (far ends of the front side) next. Keep the nuts somewhere safe. If you're really precise, you can keep each nut in the order it came off (like, tape it to a piece of cardboard, or put it in an old egg carton). I kept all the nuts with the side and end of the battery they came from (front left, front right, back left, back right), but I didn't get each one back exactly where it came from. They should be all the same.

Like I said before, you probably need the ratchet to break the nuts loose, but then you can use the nutdriver to loosen them the rest of the way. I put one hand behind my back and used the ratchet with the other hand and I didn't die, but then again, I've worked on a few hybrid cars before. You might want a rubber glove (the electrician kind, not the doctor kind) when handling the ratchet. As an alternative, wrap the entire handle of the ratchet with two or three layers of electrical tape.

You can do all the front nuts from the back seat, but you'll have to stand outside the trunk to do the back nuts.

Once all the nuts are gone, you can start on getting the bus bars off. On the back of the battery, pull the service plug cables off of their terminals, and then (gently) pull the cables out of the orange plastic clips they run in. There is a black plastic insulator around the cable ends, and you can pull that off of the battery - it may have rosin (sticky clear-ish) stuff holding it on, but keep pulling gently... it should come off.

Once the service plug cables are out of the way, pick one end of one of the orange plastic things and start pulling it away from the battery. Again, sticky stuff may hold it to the battery, but it should come. The bus bars will come with it, and stay clipped into the plastic. Get the first one off of the battery, and then get the other one off of the battery. You can then take both of them entirely out of the car if you want.

Take a look at what you have. If you look closely, you can see that there are a couple of tabs in the top and bottom wall of each plastic "well" that each busbar sits in. If you gently bend the plastic tabs away from the busbar, the busbar will pop free of the plastic. Get all the bus bars out of the orange plastic. I was able to lay them out in order on the driveway next to the car, but you may need to organize them some other way.

On the front of the battery, pull the main cables off of their terminals. You don't have to get the cables out of the orange plastic clips, though. It's easier to start with the passenger side in the front... pull on the orange plastic to pull it away from the battery, working your way towards the center. Be careful of the small wires - don't bend the plastic thing at an extreme angle, or anything.

When you get the passenger side orange plastic loose, you can start removing the busbars. The plastic wells have the same tabs as they did on the back of the battery, that you need to gently bend away to free the busbar. You will also have to carefully lift up the terminal for the small wire a little bit to get the busbar out. You don't have to take the terminal all the way out of the plastic "well" - just lift it up some - and then you can pull the busbar sideways out from underneath it. Again, keep the busbars somewhere. When you're done, the orange plastic thing stays in the car, with the small wires and big cable still clipped into it.

Once you're done with the passenger side front, work on the driver's side. It's easiest to start in the middle and work towards the driver's side. Same gig... carefully lift up terminal for small wire, gently bend up orange plastic tabs, slide busbar out, keep busbars. The orange plastic thing stays in the car on the driver's side as well.

Now you have a whole pile of bus bars and nuts.

Take a look at a couple of the bus bars. If yours are like mine, they will be relatively bright copper where they were bolted to the battery modules (a shiny ring around the bolt hole), and cruddy everywhere else. The idea is to get them (hopefully) shiny, or at least much less cruddy. The nuts may also be cruddy around where your socket or nutdriver goes... again, the idea is to get them less cruddy.

What I did with mine was to put the nuts and busbars into a plastic tray, pour in some vinegar and let them soak for half an hour or so. If the vinegar fizzes, good things are happening. After that, I put them in a different tray with plain water in it and swished them around a little to rise. Then, I used the wire brush on the busbars and nuts.

For the busbars, I laid it each one on a piece of wood, brushed one side, flipped it over, brushed the other, and then rinsed it again. For the nuts, I put the big side of the nut on the wood, held the nut with either my finger (ouch) or a flat-head screwdriver, brushed half the nut, spun the nut 180 degrees, brushed the other half, flipped it over, held it in my fingers, brushed the big side, and then rinsed it again. I used some paper towels to dry off the busbars and nuts, and then a heat gun to make sure they were dry. (A hair dryer would probably work just as well.)

I was lucky in that I didn't have a lot of crud on the battery module terminals in the car. When I was loosening the nuts, I did have some of the corrosion flake off and land near the bottom of the battery modules - I used a vacuum cleaner to suck all that stuff up, on both the front and rear sides of the battery.

I did take the wire brush to the service plug cable ends and the main cable ends, and then wiped them dry with paper towels. I also cleaned some crud off of the black plastic insulator for the service plug cable ends, but it was light enough that just wiping it with a towel took care of it.

You can wipe off the orange plastic things for the back side of the battery pretty easily. For the ones on the front, that are still in the car, it's a little harder... if you do try it, be super careful of the terminals for all those small wires.

Installation is the reverse of removal.

Seriously...

Put the busbars back into the two orange plastic things on the front of the battery first. The busbar goes in first (closest to the battery), and then the terminal for the small wire goes on top of the busbar.

Then, put the orange thing+busbars on the driver's side down over all the battery module terminals. It's pretty hard to get it off by one stud, but look at it to make sure it's right... the stud closest to the outside of the car has the big cable, and then every pair of studs after that to the middle of the battery has a busbar on it.

Then, do the same thing for the one on the passenger side. It starts in the middle where the other one leaves off, and runs to the outside end of the battery. NOTE: When you put the cable on the far passenger end of the front of the battery back on its terminal, you may see a small spark. It's not big and scary, but it's enough to notice. I have seen this twice now. (I think there is a small capacitor inside the battery computer that is either charging or discharging.)

Put the battery terminal nuts on the front of the battery. I started at the driver's end, got the first nut snug with the nutdriver, and then went to the next nut, until I got to the passenger end. I then started on the driver's end with the torque wrench and did each nut to its final torque. (53 inch-pounds). Again, I put one hand behind my back and trusted the plastic handle of the torque wrench; you may want a glove.

Put the busbars back into the two orange plastic things on the rear of the battery next. I put the driver's side one on first... in the back, the far left end of the plastic thing goes on the far left terminal. Put the black plastic insulator for the service plug cables on right after the end of the orange thing, then gently push the service plug cables back into their orange plastic clips, and put the service plug cables over the two terminals sticking through the insulator. Then, put the passenger side orange plastic thing on next... it starts right after the service plug insulator and runs to the outside edge of the battery.

Same gig with the nuts on the back... nutdriver on each one until it's snug, then torque wrench (53 inch-pounds). Fold the cover of the black plastic insulator down over the service plug cables. Once you're sure all the nuts are torqued, wipe off the flat black plastic covers, then put them back down over the orange things.

You might look inside the cover first for any signs of corrosion and wipe them out with a towel or rag, or vacuum them out, if you find them. Take a look around the inside of the battery, and then put the cover back on. When you put the cover on, hold it above the battery, line it up, and set it straight down over the battery.

There are enough bolts on the battery cover that it helps to put the first one in, turn it a couple of turns so it doesn't fall out, but don't tighten it down all the way. Go to the next bolt and do the same thing. The reason is that sometimes you need to move the cover just a fraction of an inch to get the bolt hole to line up, and that's easier if the cover isn't bolted down everywhere. Once you have all of the bolts in and started a few turns, then you can go around and tighten them down completely.

After that... it's mostly mechanical things to put back together. Put the white plastic clip on the passenger end back. Put the duct back on the driver's end - screw it to the battery cover and to the other piece of duct. Put the brackets back on the corners. Bolt the main cables back on (44 inch-pounds). Put the cover over the main cables back with the 3 nuts and the orange plastic peg.

Depending on how you need to use the car, it is possible to drive the car with the rear seat cushions and the plastic "wall" into the trunk out of it, in case you want to see how you did before putting it all back together. If you need to haul more than one other person, or if you need to keep something in the trunk you don't want the whole world to see, or if you just think that driving a partly-disassembled car would bring unwanted attention... then put the rear seat back together first.

After you put the rear set back together (or not), put the service plug back in, and flip the handle up. Reconnect the 12 volt battery. If you're really confident, put all the fuzzy trunk liners back.

Take it for a drive. If it works and stays fixed, charge your Gen1-owning friends $120/hour to do this to their cars.

Again, this is based on my experience on my own car, swapping the traction battery once, and working on P3009 once. I am not affiliated with any companies mentioned.

 

Great writeup!

 

Thanks for that write-up! I would add a couple things ...

Back when the earliest Gen 1s had an electrolyte leaking problem, there was a service campaign to add sealant, and with that campaign there was a PDF instructions document, T-CP-40G-0119-W.pdf, which is chock full of detailed instructions and pictures (much more than the regular repair manual, even), all about working on the battery. Great resource, might be findable on the web, or at techinfo for sure.

I would double-check that ... the 40G pdf used the figure 48 inch pounds exclusively, and repeated it many times. They actually did not even allow an adjustable torque wrench, but specified a fixed, factory-calibrated 48 in-lb T handle wrench for the dealership to obtain as a special service tool. I think I trust myself enough to use a regular long-handle torque wrench for that (carefully!), but I would definitely set it for 48, not 53.

Toyota also specified to wrap vinyl tape around any socket you're using, down where you'll be fitting it on the nuts. The idea is, you're not just protecting yourself from possible shocks, but the battery from possible shorts. The risk is most obvious when you have the bars installed on one side of the battery and now you're doing the other side; an accidental tap of the socket between the wrong two adjacent terminals anywhere on the battery would be a 15 volt short with upwards of 100 amps available.

The pdf also has lots of advice for being safe around any of the potassium hydroxide electrolyte that could possibly have leaked out. You should assume that any substance you find on the battery modules or case in there is that, and it is not friendly. If you might have touched it with your hands, don't go near your eyes for sure. They recommend having some boric acid water solution already mixed up for neutralizing any of that stuff ... washing it off anywhere it is on the battery, and anywhere it gets on you.

When taking the battery apart, one way you can get it safer to work on as quickly as possible is to remove the bus bars from one side in a strategic pattern. Toyota started the pattern with the service plug safety, which interrupts the battery just about in the middle. If you think of the normal battery voltage as 274 (may as well just say 300, a nice round number that's totally realistic when well charged), pulling the service plug has instantly broken it into two 150 volt batteries. That's safer (from what I've read, if you inadvertently start an arc at 150, it won't self-sustain), but people still get killed by house voltage at 120, so it still isn't what you'd call benign.

If the first two busbars you take out are from the middles of those two halves, now you have four, 75-volt batteries. There have been fatalities at 75 volts, but usually under sort of freak circumstances as I understand it. If the next four bars you take out are roughly in the middles of those, you've made eight batteries of under 40 volts, and then might as well remove the rest of the bars in any old order.

Same idea also works on reassembly.

-Chap