Gen 1 Prius entering the hidden self-diagnosis mode
This is how you can enter the hidden diagnostics menu on a Toyota Prius Generation 1. Very handy way to test the 12-volt auxiliary battery when you don’t have a volt meter. This method should work on all Prius models built from 1997-2003
The Toyota Prius has a 12-volt auxiliary battery to run the computer, alarms, central locking and interior lights. It is also the source of signal to start the hybrid system. It is a pretty small battery just a little bit bigger than a motorbike battery and it has to do a lot of work.
If you leave the car unused for a couple of weeks this 12-volt battery will be drained by these systems and you will not be able to start the car.
The Prius doesn't have an alternator instead it charges the 12-volt auxiliary battery either from the petrol (gasoline) engine or from power recovered from coasting and braking or a mixture of all three whichever is the most efficient.
If you drive for about 20 minutes the 12-volt battery will be fully charged.
Sequence:
1 Make sure the car gear stick is in park mode.
2 Apply the hand brake/foot brake
3 Press your foot on to the brake pedal
4 Put in the ignition key in and turn to the first notch. Accessory mode (ACC)
5 Turn the radio on
6 Press the audio button
7 Press the display button
8 A rectangle appears around the radio buttons
9 Press on the left-hand inside part of the pane top to bottom 6 times
10 The hidden menu appears
11 Press menu
12 Press display check
13 Press vehicle signal check
14 You can now read the condition of your 12-volt auxiliary battery.
Keeping a check on its condition is a good idea as new auxiliary 12-volt batteries for the Prius are expensive £150+ ($200+) so this method of accessing the hidden diagnostics menu could save you a lot hassle and money.
You cannot bump start a hybrid so you will need to either charge up the battery or get a jump start which is quite an issue on its own as there is a set sequence for jump starting a hybrid too. Do it wrong and you could end up blowing an expensive fuse or worse.
Both cars must be turned off with the handbrakes on and both in park mode.
Connect the positive (red) cable to the jumper car first then to the positive terminal on the battery of the car to be jumped.
Next connect the negative (black) cable to a piece of exposed metal (bolt or chassis member) on the jumper car and then the other end of the cable to the negative terminal on the car to be jumped.
Start the jumper car. You will hear the car to be jumped make a slight noise as it initializes.
Leave it for a few seconds and then start the car to be jumped.
Sometimes people can be confused when the jumped car's petrol engine doesn't run immediately. This is normal. The car is now running and if you press the accelerator the petrol engine will start.
Now take the jumper cables off in the reverse order that you put them on.
You can jump start a Prius from any car but a Prius cannot jump start a non-hybrid car as the battery is not strong enough from what I have read.
Trust me I’ve just been through this and blew a £75 ($99.00) fuse by not jumping correctly.
To repeat myself, as the guy at the garage had no clue that the car had no alternator and wanted to sell me a new battery.
The Prius doesn't have an alternator instead it charges the 12-volt auxiliary battery either from the petrol (gasoline) engine or from power recovered from coasting and braking or a mixture of all three whichever is the most efficient. If you drive for about 20 minutes the 12-volt battery will be fully charged
This little hack saved me £150 ($200) and a lot of headaches.
Hope you found this post useful. In 7 years’ time my Prius will be an antique vintage motor car and I think it’s going to make it. 😊
My video is at DLive
