General Disclaimer:   (HV) (DC) injury or death hazard,   use at your own risk,   may void warranty.

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 and Some Toyota Contacts. This might come in handy if you need to look up some DTC, CEL, error codes. This PriusChat post and KB article may lead you to other Known Hacks and Easter Eggs for the Prius.

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.
  • This doesn't works on european models!

Disabling EV Button Beeps

  • Disabling button beeps!?
  • Most beeps are generated by a "sounding buzzer" inside the "Combination Meter" (speedometer, etc.). They are controlled by messages in the BEAN bus. There is no way of disabling only particular beeps in hardware; instead, beep commands would have to be intercepted in the BEAN bus.
  • While many beeps may be turned off through customization (requiring the "Hand Held Tool"), EV Mode beeps do not appear to be customizable

Tachometer Signal

Found it at which has an image in the mods-Buttons/Guages section, 04_TachECM.gif contributed by Wayne Brown, which shows ?pin 23? (the 5th down in the 3rd row of pins) on the top connector on the ECM to be a tach signal wire which should drive a standard tachometer. [7]

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 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 continuously 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. More discussions can be found here: [8], [9], [10].

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" or "Volume" 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!

This doesn't works on european models!


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"

See Prius EV Mode Button and more Prius EV fun on the Prius PHEV page.

EV-Mode and your Warranty

See Prius EV Mode Button#EV-Mode and your Warranty

Enabling even more Electric Vehicle features

Those features which you may associate with Hybrids may actually be electric vehicle features such as no idling, quiet operation, and regenerative braking. Unfortunately, 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 more than capable of supporting a large number of BEVs or PHEVs before it would require additional capacity, in fact it may help to load balance the grid.