Hymotion and 52 MPH EV Mode -

[astrand]

_H*

Originally Posted by hobbit

If you're playing with this, note that there are at least
*three* power leads to the engine ECM: +B at E7-4, black, main
"ignition" power; +BM at E7-5, gray wire, special power to the
ETCS throttle motor; and BATT at E7-6, red, always-on memory
keepalive. Breaking +B is sufficient.

Would it be safe to cut +B power during drive? Restore power after a few seconds? As pointed out earlier, removing the EFI fuse is one way of triggering this. In that case, +B power is lost, and of course a fuse could blow during drive. But if you compare this with just cutting +B, the difference is that in this case all the other systems on this fuse are still powered. Otoh, the +B connector could potentially come loose during drive, and it would be a strange design if something bad happened as a consequence.

Has anyone actually tried switching +B power on/off during drive?

If switching on/off power feels bad, another idea could be to disconnect the ECU from the CAN-bus. That should also trigger the "drive on motor mode", as Toyota calls this error condition.

[linuxpenguin]

Hi Guys,

I'm sure that several people have already posted about this, but there are a few things about this forced stealth mode button you should know.

You should know that using forced stealth mode sets an OEM diagnostic trouble code (DTC) which requires clearing /all/ stored diagnostic data to remove. That includes all stored service data and emissions data (which is legally required for emissions standard testing). It's not the end of the world, but since most states use OBD2 for emissions testing it can cause the vehicle to fail the emissions test (hilarious yes, but true) if forced-stealth mode has been used recently.

You should also know that driving the vehicle faster than 42 MPH in forced-stealth mode risks over-revving the drivetrain. Please see ( www . eahart . com / prius / psd / **Remove the spaces--couldn't post the full URL**). Note how if you drag the MG2 dot beyond 42 MPH the red zone becomes critical which indicates the motor is potentially being over-revved (Yes, it's true. Argonne National Labs has verified it). This can cause long-term vehicle damage. There is a reason why Toyota always forces the ICE on when you go above 42 MPH regardless of the accelerator pedal--just because Toyota allows the vehicle to go above 42 MPH in forced-stealth mode does not mean it's good for the car. Forced-stealth mode (also known as limp-mode) is designed to be used in emergency situations (critical engine problem or ran out of fuel) as an absolute last resort.

You should also know that in the event of an emergency where you need the full power of the Prius motor + engine, you will not be able to use the engine until you completely stop and restart the vehicle. That means that if you have to get out of an intersection quickly you will not be able to (you'll only have at maximum 21 KW from the motor). This demonstrates a pretty big safety risk.

In the event that you forget to turn the car off and exit forced stealth mode in time (when your PHEV pack depletes for example), the OEM pack (if you are using a CalCars style conversion) will drain into the 30s before the vehicle finally sputters out. This causes extra strain on the battery and will reduce the lifespan of your OEM battery.

If you're OK with all these things then it's up to you if you still want to use it but I thought I'd lay out the risks.

Andrew