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User:Rjf/Prius Modifications

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See also the Toyota Prius page.

This is all entirely unofficial and I am not modifying the Prius untill the Insight is back on the road. Lookin for accessories? Check out japanparts.com and sigmaautomotive.com. Some Toyota Contacts

Reminder Light Reset

  • Power on car, Cycle ODO/TRIP, stopping on ODO, Power off car.
  • Power on, while holding the ODO button
    • Wait for reminder light to go out, then release ODO button.

Disabling Reverse Beep

  • Power on the car, Cycle ODO/TRIP, stopping on ODO, Power off the car.
  • Power on, within 6 seconds, hold ODO for at least 10 seconds.
  • While still holding ODO shift into Reverse and back into Park.
  • b-on shows on speedometer display, press ODO to cycle to "b-off".
  • This also works for the seatbelt beep, replace shifting with buckling/un-buckling.


Tachometer Signal

Found it at vfaq.net which has an image in the mods-Buttons/Guages section, 04_TachECM.gif contributed by Wayne Brown, which shows ?pin5? to be a tach signal wire which should drive a standard tachometer.

Touch screen diags, for 2004 or newer

Use of this information might result in disabling your vehicle, use it at your own risk.

  • Hold Info button while turning the lights on and off 3 times, you can wait for system checks. -OR-
    Press the display button, then press the left upper and lower corners within the display settings box 3 times.
    • If codes exist press LAN Mon, then CHEK to show codes or hold code clr to clear codes.
  • From the initial screen, hold Info button while turning the lights on and off 3 times
    for Model Info Set Up (type) screen. I do not know what these do, use at your own risk.
    • Types are : 690N 740N 836N 783N 620N 808N 480X 900N 382X 290X
      Types are : 901N EMV AVX(ten) AVX(nat) AVX_HV(ten) AVX_HV(nat) 749N
  • Use the Menu button to reach the Diagnosis Menu, press the Display Check and then
    Vehicle Signal Check to show the accessory battery voltage and other information.
  • From the Diagnosis Menu press upper-left then lower-right screen corners for PDM menu.
    • All buttons except for perhaps the Init. BackUp may be safe to use.
  • From PDM screen, hold Info button while turning the lights on and off 3 times for an untitled screen.
    • Here you find a number of options stating success or PGM rqd including TKM, Flicker,
      setting:Tape/MD, setting Address:110H/120H, setting AC:off/on, and setting Auto:off/on
  • Hold the physical Display button to exit at any time, or simply power off the car.

Thanks to vsssfamily.net and images! I also found a Spanish site with lots of photos English Translated.

Disabling Traction Control

WARNING: The shop manual apparently states in no uncertain terms that this procedure must NOT be used to drive the car as damage to the transmission could occur due to traction control being defeated.

  • Follow the sequence below (quickly - within 60 seconds)
  • Set Ign switch to ON, not READY (Power button twice, no brake)
  • While still in "P" fully depress the gas pedal two times.
  • Select "N" fully depress the gas pedal two times.
  • Select "P" fully depress the gas pedal two times.
    (LCD display will indicate a !Car! in upper left corner of screen)
  • Turn key directly to "start" to start the engine (brake+start button)

It forces the ICE to run continuosly and defeats the traction control system. Normal operation returns after turn off and reboot. Unlike EV-Mode this is strictly a diagnostic function and should not be used under normal situations. Thanks to Peter Rawlinson for posting this on the Yahoo Prius_Technical_Stuff group.

Disabling Navigation Lock-Out

When moving faster than a very slow speed, many of the navigation setting buttons are disabled (grayed-out). This sequence will override the lock-out until the car is powered off.

  • Press the "Menu" button (hardware button)
  • Press the "Voice" icon on the display
  • Press the upper left corner of the display, where the speaker icon is
  • Press the lower left corner
  • Press the upper left corner again
  • Press the lower left corner again
  • The screen should change to a diagnostic screen
  • Hold the "Override" button for several seconds until it changes to black

Warning: do not play with things on this screen that you don't know about!

Reprogramming the Key Fob

Regen/Friction Brake indication

Hobbit has put put together a hydraulic brake pressure sensor system to give feedback on the brake system.


Enabling EV-mode Button "H14 #27 to ground"

The EV-Mode Button is a standard part of the Japan and EU Prius but was not installed in the US versions, perhaps because of extended warranties in Ca due to AT-PZEV regulations and qualifications criteria. The US Prius is still entirely aware of the EV-Mode though it can never get the signal or command to enter or exit the mode because a wire, light and button are missing. EV-Mode is a very enlightening feature as it encourages the Prius to stay in its electric mode for far longer than it normally would. It will normally drive 1 to 2 miles and up to 3 miles on a fully charged battery, after which it must restart the engine and use gasoline to recharge the battery. It is not a good idea to fully cycle the battery often as this decreases any battery's life and is not helpful for mileage if used improperly. If used correctly is can be advantagious for times when you know you won't need to start the engine. It's also fun for showing off and offers a small glimpse of the potential of electric vehicles.

The ev-mode funcion itself is activated and deactivated by grounding the H14 #27 pin on the HV ECU located behind the glove box(s). CoastalTech.com (ph) has a well integrated 3-wire EV-Button kit with easy instructions or prius-evbutton-install.pdf from calcars.org and EV-button-Y.html from vfaq.net have more information for "do it yourself" kind of people like me. I also found a factoryEV.pdf by ScubaX at PriusChat which I had hoped would lead to the ev-status illumination solution, but instead simply found that the dimmer switch white/black stripe wire to be ground(-) and the grey wire to be illumination control. I'm looking for the steering pad wire diagram as I'd like to use the recirculation button as the ev-button, but it's probably not a simple ground.

Four things that cancel EV-Mode.

  • Battery reaches 2 out of 8 battery bars worth of charge.
  • Speed reaches 34mph.
    • EV-only driving regularly occurs even at freeway speeds when there is ample battery energy.
  • Accellerator pedal is depressed more than half to 3/4 of the way down.
  • Pushing EV-Mode button.

Things you need to add the feature.

  • 22 gauge wire, about 6 feet.
  • Standard Philips screwdriver.
  • Small Jewler's screwdriver.
  • Soldering may be required.
  • 1/2 to 3 hours of time.

EV-Mode and your Warranty

  • Regarding your warranty - Yahoo PriusPlus post.
    • http://www.sema.org/main/semaorghome.aspx?ID=50096 The Law
    • Federal law sets forth requirements for warranties and contains a number of provisions to prevent vehicle manufacturers, dealers and others from unjustly denying warranty coverage. With regard to aftermarket parts, the spirit of the law is that warranty coverage cannot be denied simply because such parts are present on the vehicle, or have been used(see Attachment A).The warranty coverage can be denied only if the aftermarket part caused the malfunction or damage for which warranty coverage is sought. Disputes in this area usually boil down to arguments over facts and technical opinions, rather than arguments over interpretations of the law.

Enabling even more Electric Vehicle features

Those features which you may associate with Hybrids may actually be electric vehicle features such as no idleing, quiet opperation, and regenerative braking. Unfortunently as of yet many of the greatest aspects of battery electric vehicles, or BEVs are not available in current Hybrids. The EV-Button still doesn't allow you to recharge the batteries with electricity from a fuel source of your choice. Though it does hold the potential of a fuel choice which is already widely available and potentially renewable. By Plugging-In to an electrical outlet you can dramatically improve your gas mileage. The Grid is far more capable of supporting a large number of BEVs or PHEVs before it would require additional capacity, in fact it may help to ballance the grid.

File:04 HV & PbAcidParallelTie2.jpg
HV tie-in

Much thanks to Wayne for discovering and then sharing his discovery of how to install the ev-button at Yahoo in Feb of 2004. He also shared with us some interesting technical info regarding the effects of the ev-mode, "136 Amps (136 Amps X 202 VDC = 27.4 KW = 36.7 Horsepower)" vs "45-50 Amps (10 kW or 13 Horsepower)" in stealth mode (non ev-button electric mode). Wayne was doing a lot of work with additional battery capacity tie-ins. He wrapps it up here, Button Part Number, 31% gain, re-enable confirmation, more details, BMS details, some speculation, 7.5ah aux battery.

File:Prius Charger.jpg
THS Charger

Projects like the Prius Plus, CalCars.org, EnergyCS, and EDrive


PHEV Ratings

A PHEV is a Plug-in Hybrid Electric Vehicle, usuaily also augmented with a -## that denotes it's BEV range, a PHEV-20 would have a 20 mile range on electricity before gassoline would be required.

There has been a lot of discussion on rescent "250 mpg" claims from the Prius+ folks and/or the press and media from people who point out the lack of consideration for the electric fuel that skews those mileage figures. I Posted this and it's the latest summary of the whole situation.

Prepair for a Tangent !
--- In priusplus@yahoogroups.com, "Robert Strattan" wrote:
> This then gves a more accurate indication of the fuel
> economy related back to raw energy used from fossil fuel sources.

Wouldn't it be interesting to use raw solar energy as the original
source and then re-run the analysis. Here's what I came up with:


I can see both sides of the argument, some prefer to consider the electric energy usage seperately since it's properties, like Cost, CO2, and Effeciency vary far more than gassoline. Some people may even generate their own electricity, in which case their electric energy is essentially free once the initial investment in the collection technologies is paid off.


Here's [5] what I've come up with.

My PHEV empg ( unofficial )

This Is a far better explanation. I use $0.06/kWh. The Prius achieves 3 miles per kWh and 50 mpg. I'm using 33.6kWh/gal to calculate kWh Equivilant mpg or empg. Calculation formula is:
Total Distance - PHEV-Range = Distance using Gassoline.
Distance using Gassoline / gas mpg = Gassoline Consumption.
Gassoline Consumption + kWh gas equivilant / Total Distance = empg.

  • PHEV-20 (6.6 kWh, $0.40) = 0.2 gas gal equivilant
    • Total Distance, Gassoline used = Empg / mpg (electricity considered seperately)
    • 20 miles uses 0.00 gas gal = 100 empg / Inf mpg
    • 40 miles uses 0.40 gas gal = 67 empg / 100 mpg
    • 60 miles uses 0.80 gas gal = 60 empg / 75 mpg
    • 80 miles uses 1.20 gas gal = 57 empg / 80 mpg
    • 100 miles uses 1.60 gas gal = 55 empg / 62 mpg
  • PHEV-40 (13.3kWh, $0.80) = 0.4 gas gal equivilant
    • 20 miles uses 0.00 gas gal = 100 empg / Inf mpg
    • 40 miles uses 0.00 gas gal = 100 empg / Inf mpg
    • 60 miles uses 0.40 gas gal = 75 empg / 150 mpg
    • 80 miles uses 0.80 gas gal = 66 empg / 100 mpg
    • 100 miles uses 1.20 gas gal = 62 empg / 83 mpg
  • PHEV-80 (26.6kWh, $1.60) = 0.8 gas gal equivilant
    • 80 miles uses 0.00 gas gal = 100 empg / Inf mpg

Note also that various vehicles with achieve different miles/kWh and mpg. The ACP T-Zero achieves 6miles/kWh and ~30mpg. ...T-Zero table...

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