Just bought a 2003 Gen 1: First Steps?

You don't want to guess. "Hybrid system general fault" is a decent paraphrase, and there's a lot more to the hybrid system than just the battery; there are a couple hundred trouble codes for telling you what the actual issue is, and many have nothing to do with the battery at all.

It often seems, maybe because the battery is the most obvious new thing people know is in a hybrid car, it comes to take center stage in people's minds at the expense of thinking of the car as an interoperating whole.

You might consider getting some other app to use in diagnosing problems with the car, in addition to Dr. Prius, which is mostly known for its extra information screens geared toward trying to predict the battery life. Dr. Prius can also retrieve some trouble codes from the car, but not all of them, and when problems come up, a scan tool that can read all of them is usually the thing you want.

P1 codes are manufacturer-defined. If there's some other car model out there where P1437 is an evap code, then that would be included in your web searches even though it's a bogus result for a Prius; that's the danger of doing web searches for manufacturer-defined codes. (Realistically, there probably isn't a car model out there that would use a P1 code for an evap issue, as many cars have evap systems and there are industry-standard P0 codes for evap issues.)

In a gen 1 Prius, P1437 is about the vacuum-powered actuator for a valve in the exhaust system ahead of the catalytic converter. This thread may be of interest.

P1437 would light the check-engine light, but I don't think it would light the hybrid warning. If you have the latter, then it is likely there are other trouble codes to be read that Dr. Prius did not show you. One of the other tools or apps that can show all of the codes in a Prius might be needed to get the whole story.

If you have an old gen 1 Prius as a project, making sure you have your own scan tool that can read all the trouble codes will be a very good investment.

 

Does the car have the OEM catalytic converter? The most obvious cause of the 1437 is that the OEM cat was stolen and replaced with a non-OEM that doesn't have the vacuum valve that recirculates exhaust. If it has the OEM cat, that value is probably stuck open or stuck closed (P1437 or P1436, IIRC), often because it's gotten rusty if the car spent time in a snow-prone area.

If you have the OEM cat - you scored!! Simply swap in an aftermarket cat and recycle yours to get half your money back for the car (I've gotten $700-$900 depending on the price of the precious metals at the time). Replacements are less than $100, plus a muffler shop welding it to the exhaust pipe. Remove the vacuum canister from the OEM and have the shop tack weld it to your new cat, but take off the arm that connects to the valve so it's not flopping around (the replacement doesn't have the valve). Swap over your ox sensor and reconnect the vacuum hose to that cannister (you're hacking that sensor data by making it think the valve is still operational. Owners whose cat was stolen (most frequent reason) won't have that canister, but any sealed canister of the same approximate volume works. Others have used a Honda Goldwing cruise control canister, you can also fabricate one. Even plumbing PVC cut to size and sealed caps on each end with a hose fitting inserted and sealed can work, for example. If you're replacement canister isn't metal, you can trace its vacuum hose up to the throttle body, cut the hose and attach to your new canister which you just mount/lay anywhere under the hood that you can.

I have spares - OEM canisters and a Goldwing canister.

Your dash light isn't showing any problem with the battery, it's pointing at the ICE engine. So it could just be that 1437 code. SYK, the car still drives OK with that code and no vac valve. Maybe a little problem in cold weather and a little worse MPG and maybe a problem passing inspection. That valve shuts to allow the exhaust to heat up, and opens at operating temp (or vice versa, I can't remember). Your ox sensor will reflect the colder exhaust in winter and compensate with extra fuel until warm.

Also, it's my understanding that Dr. P app is kinda useless on Gen1 - different network protocol so it can't capture the data you want. Maybe it's been updated, but I doubt it. No one updates for Gen1.

 

Other things to check would be the inverter coolant pump, like all Prii. with just the key on, the fluid in the reservoir attached to the inverter should be dhurning slowly. Keep your throttle body and MAF sensor clean.

If this car was in snow a lot, it can have a rusted filler neck. Reach up inside the passenger rear wheel well to find that filler tube and feel around the outlet, especially on the top side. Snow will get stuck/packed around the tube up there and result through. It will shut your car down. I have a couple of those too - very easy to replace.

I have a bunch of these cars including several parts cars, LMK if you need anything. I sell parts real cheap. My FB page: JinWan Motors

 

Well to be even more exact, it isn't about "a" vacuum line and "a" sensor, it is about "the" vacuum line serving the actuator for the HCAC bypass valve in the exhaust, and the "vacuum sensor for HCAC system" that monitors that vacuum line to confirm the movement of that bypass valve. That vacuum line has its own intake-manifold nipple and a check valve; it's not shared with the evap purge line attached at the throttle body.

The long and short of it is that there is a vacuum problem in the HCAC system, which Toyota assigned its own trouble code in the manufacturer-defined P1 space. For evap system issues, they use the SAE-standard P0 codes already defined for evap issues.

 

On my 2001, with everything warmed up, no A/C or heater, a light touch on the gas pedal, and a level road, it will accelerate on electric up to about 11 or 12 mph, and then the engine starts.

Some Gen1 front brakes have kind of an interesting problem. The pad doesn't apply to the disc evenly across the entire radius of the disc - you get rusty spots next to shiny spots. I don't know why. (Imagine a CD with only 20 minutes of music on it, or an LP where the first few "tracks" are rough vinyl and then regular grooves on the last couple of tracks.)

You can inspect the outboard side of both discs by looking through the front wheels, if it has the stock wheels. On mine, it happened on the inboard side of both discs. You might be able to see it by cranking the steering wheel to the limit, jacking up the car, taking off the wheel, and trying to get your eyeball in between the splash shield and the inboard side of the disc. If you can't see it, get some brake clean and paper towels. With the brakes cool, stick your finger in between the splash shield and the disc; you can feel the roughness if this is happening. Then, clean up the spot you touched with the brake clean and paper towels.

I had the rotors turned at the car parts store, put new Toyota pads on it, and that stopped it for many tens of thousands of miles. I mentioned it to the independent mechanic I use, when I took the car in for something else, and he said "yeah, Priuses do that". So it's something to check.

I recall there isn't a screen, but it's been a little while. There is a pan you can take off, and a magnet in the pan you can clean; it's normal for there to be a little bit of metal "fuzz" on the magnet. (The magnet is stuck to the pan, not on the drain plug.) Toyota says you need a new pan gasket, which I always do. They also call for a weird Loctite part number on the pan bolts - I suspect it's one of those things that they buy in a 208.2-liter drum that mortals can't get. I use blue Loctite from the car parts store and it hasn't leaked yet.

Toyota also says to replace the crush washer on the ATF drain plug every time. 90430-A0003 at your friendly local Toyota dealer; they probably have them on the shelf. I also recently discovered that the Dorman 095-149 aluminum crush washer is pretty much an exact replacement for the Toyota part; a bit over $2 and on the shelf at an O'Reilly near you. (The same washer works on the ATF fill plug and the transmission coolant drain plug.)

When you're laying there under the car, note that there are two drain plugs on the transmission. The one in the middle of the black sheet-metal pan is for the ATF. The one about four inches inboard of that, that goes into an aluminum-colored cast-metal housing, is for the transmission coolant. Try not to get them mixed up. Don't ask me how I know this. <_<

The fill plug is about halfway up the side of the transmission, and takes the same crush washer. I bought a "spout" that fits the ATF bottles and has a long hose; Googling shows me I probably got the "Hopkins FloTool Transmission/Gear Oil Spout", part number 10106, about $6 at the local auto parts store. I replaced the clear hose that came with it (too short) with a slightly longer piece of vinyl hose from the hardware store - the kind with the white braided "thread" reinforcement. Buy, like, 3 feet of hose, and then trim it to taste once you're in front of the car.

Start with the "nozzle" on one end of the vinyl tube, and nothing on the other end of the vinyl tube. Remove the fill plug. Thread the hose down from the top (it needs to start in the vicinity of those two little bleeder nipples that are in front (FRONT) of the silver "Toyota Hybrid System" box), and plug the nozzle into the fill plug hole - real good so it can't fall out. Up top, thread the spout/valve onto the ATF bottle, turn the valve off, plug the spout/valve into the vinyl hose, hold the bottle up, and turn the valve on. Several rude noises later, the bottle will be empty.

Toyota says the refill capacity is 4.9 quarts. I have sometimes had to add slightly more than 5 quarts. They say the oil level should be 0 to 5 mm below the bottom edge of the filler hole; what I do is dump 4 quarts in without looking, hook up a fresh bottle, and then start doing a sequence of "squeeze bottle, shut off valve, go under car and look". Once it starts dribbling ATF out of the fill hole, it's full. Put the fill plug back in with a new crush washer.

You can get 6-packs of Toyota T-IV ATF on Amazon for roughly $50, delivered, in the US. One dealer near me has them on the shelf for $7.50, but another dealer is... more than that. Check locally for the best deal.

If you don't have any data on when the engine coolant or transmission/inverter coolant were last changed, you might consider changing them. They both take the same stuff - Toyota Long Life Antifreeze/Coolant, cut 50/50 with distilled water.

The engine coolant is just like your father's Oldsmobile; there's a drain cock on the back side of the engine, on the passenger side. Put your fingers on the back edge of the oil pan and go up from there and you'll find it. Fill up the radiator, then fill up the overflow bottle, then run the engine until the heater starts working, and fill up the overflow bottle again. The next couple of times you drive it, check the overflow bottle. Once it stays full, you're done.

The transmission/inverter coolant is drained by taking out the drain plug on the aluminum-colored cast housing on the transmission. It's filled by adding coolant to that tiny little reservoir (nylon-colored body, black top) between the engine and the "Toyota Hybrid System" box... and then doing a complicated bleeding procedure to get the air out.

I have always used the Toyota coolant in both applications - you can get gallon bottles of it on Amazon. If I really wanted to save a buck, I'd consider using the "import red" stuff from the car parts store in the engine, but still use the Toyota stuff in the transmission/inverter. The Toyota stuff is good for 600 volts dielectric, which the "import red" stuff may or may not be.

More soon.

Get Techstream.
Get Techstream.
Get Techstream.



Yes, you have to buy a "Mini-VCI" OBDII-to-USB cable (about $30-$40 on Amazon). Yes, you have to schlep a laptop (or a desktop, lol!) out to the car. It is 100% worth it.

You can see the same stuff a dealership tech can see. You can even command some of the systems in the car on and off for testing.

This is what I did, in 2018, to get set up with Techstream: Attempting to get our original 01 Prius back on the road | PriusChat

I have run Techstream on Windows XP (32-bit) and 8.1 (64-bit). There's a little bit of extra futzing around you have to do to get the Mini-VCI driver to install on 64-bit Windows, but you only have to do that once. I would *assume* it would also work OK on Vista and 7. I haven't tried it on 10 or 11; if I had to, I'd try 10 first. You also need Java; 32-bit Java, even if you have a 64-bit OS.

Several years ago, I put an adapter from BlitzSafe into a 2000 brand H (Japan) car to give it an "aux" input it lacked. The stock radio had analog audio inputs (for the optional CD player or changer, I think), but it also needed to hear something on the data bus to actually turn those inputs on. The adapter had enough microprocessor in it to satisfy the radio; you pushed the "CD" button on the stock radio to activate the "aux".

At the time, I looked to see if they offered one for a Prius, but they didn't. The connectors on the ones they sold for contemporary Toyotas looked an awful lot like the CD-player/CD-changer connectors in the Prius manual, but I never tried it. It might be worth an email to them about it.

I've also been told that the Prius radio and CD speak Fujitsu Ten's "AVC-LAN" network. Maybe somebody has some code for a PIC, Arduino, or equal that would get you going.

I've never tried to take mine apart, but I've been told that the "waterfall" or "bezel" on the Prius is prone to breaking if you try to remove it. It's the giant T-shaped piece of plastic that starts down around the heater and A/C controls and goes all the way up to the touch screen and A/C vents - you can see the top part of it in your photo. I mention this because you might have to remove it if you need to remove the audio hardware.

I am not affiliated with any companies mentioned.

 

For what it's worth, the original cat on my 2001 started to give out around 160,000 miles or so, when the car was about 11.5 years old. It threw a P0420 code, so I crawled under the car and made sure that cat was still there, O2 sensor wiring not beat up, etc. All that was good, so I cleared the code and motored on. The code stayed gone for several months and then came back, with increasing frequency - every other tank of gas, every tank of gas, twice in a tank of gas, down to every 100 miles or so. Back then, you could get the original cat from Toyota, so I had an independent shop put one of those on.

When 2001s were new, you got the first 5 regular services for free at the dealer. One of those included the cabin air filter. The stealership I took mine to said they "never" did those because "they have to take apart half the dash". I asked if they could at least give me a new filter so I could give it a try; they agreed and then ghosted me. I got a new filter on my own and it was easy to change, as you now know. Lesson learned: Stealerships mostly suck.

If the filter was full of dirt, leaves, etc, there's a small chance that the A/C evaporator drain tube got some crud in it over the years. When mine got crudded up, it ended up peeing water onto the front passenger floorboard when I went around a corner after the A/C had been running for a while. You can see the end of the tube from under the car, but as I recall, I pulled down the carpet at the left edge of the passenger footwell, pulled the hose up and out of the grommet in the body, squeezed the tube (and promptly got more water on the floor), worked on it with a piece of solid copper wire and a shop-vac, and finally stuck it back in the grommet. I've only had to do that once, so far.

I included the note about the Dorman part because 1) auto parts stores are more common than stealerships and 2) auto parts stores are open on Saturday afternoon and Sunday.

I took the factory plugs out of mine for inspection around 75,000 miles, just because I couldn't believe that plugs could last that long... and they were fine. I put them back in and ran them until about 137,000 miles.

Mine tend to get a white-to-yellow deposit on the ceramic insulator for the electrode; not enough to foul things up, but enough that you can tell that they've been in there for a while.

I'm told that when a Gen1 starts, it holds off the fuel until it knows the engine is up to speed, then applies fuel and spark. There may be a similar "soft" shutdown sequence. Maybe that helps the plug life.