One of my Prius won't start the engine....

Are the relays clicking in the rear and staying open when you boot the car with foot on brake??

 

Does the car go into "Ready"?

Did you have the orange safety plug removed from the hybrid battery?

What is the voltage of the 12v battery?

You need the 12v battery to power up all the ECUs in the car for the car to go into Ready mode, and you need a certain amount of charge in the hybrid battery to start the engine.

 

NO, the hybrid battery needs a certain amount of charge to be able to start the engine.

Use your Autel scan tool to read the voltage of the hybrid battery.

 

You first need to use your Autel or open the battery and use a meter to measure the voltage of the hybrid battery to determine what the next step is.

 

When an older hybrid car sits for months the NiMH cells in the hyrbid battery pack self discharge and because the cells are older they tend to discharge at different rates so your pack is no longer balanced and has a low charge, aka: P3000.

So what you're in need of is a charging and balancing of your hyrbid pack. Maxx Volts and www.hybridautomotive.com sell commercial products but they're overpriced. So instead you can something with this type of specs for a much lower price and it has many more uses: www.alibaba.com/product-detail/KUAIQU-SPPS-D3001-232-300V-1A_1601010961235.html and follow the instructions on the hybrid automotive site .

You'll also want to send 12v power to the battery cooling fan because keeping the battery pack cool while charging and balancing is essential.

 

If you disconnect the 12v from the car, it will reset all the ecus, clearing all DTCs and putting them to default values, including telling the car the HV battery is at about 60% SOC. Usually, this is enough to get one or two start attempts, but obviously you're using a relatively depleted HV battery, so if it doesn't start, the battery is really drained now.

If the battery is in very rough condition, the ecu may recognize it has a problem before the start cycle can occur and then you're just SOL until you can get a charge on it.

 

if it makes 'ready', you can put it in neutral and push it.

 

For that matter, you can go plain IG-ON (two button presses, no brake), then press the brake and shift to neutral and push it. There is no need for the hybrid system to operate for shifting to neutral.

 

P 3000 you need sub code like 384 or such ?

 

It is not likely, but one way you can know for sure is to measure the voltage with a voltmeter. If it is 202 V or more (210+ V would be better), you're in luck. Otherwise, you need to invest in charging and possibly discharging equipment to progress.

 

Removing the hybrid vehicle (HV) battery from the car will not serve any useful purpose in terms of slowing self-discharge because the HV battery is mechanically isolated from the rest of the car by way of the relays.

The rate of self-discharge will depend on the age and condition of the battery. Probably the most reliable way to ascertain the self-discharge rate would be to measure it.

 

just sits they're in the place ya put it. Hot or cold . No connection . Volts amps no move it. tecnologia

 

While it's sitting there, it self-discharges, at some rate over time.

The owners' manual provides:

... (traction battery), the battery does not need to be charged from an
outside source. However, if the vehicle is left parked for a long time the
hybrid battery will slowly discharge. For this reason, be sure to drive the
vehicle at least once every several months for at least 30 minutes or 10
miles (16 km).​

(cribbed from a 2010 owners' manual, gen 2 probably has similar wording.)

That's harder to do if the battery is out of the car. (On the other hand, that can simplify access for recharging it if you have suitable equipment and it's needed.)