The hybrid concept of combining an internal combustion engine with an electric motor and electric power supply is becoming more popular as vehicle manufacturers look to reduce emissions and fuel consumption in vehicles. Consumer interest in these vehicles has been favorable, which is why you can expect to see more of these types of vehicles on the road and in your shop. However, hybrid vehicles, with their high-voltage electrical systems, need to be approached differently when servicing their motor and engine systems.
As a shop owner, you should familiarize yourself and your technicians with some of the safety and servicing issues surrounding hybrid vehicles. And because some technicians in rural areas and various towns also serve as community firefighters, much of this information will be useful to them should they come across a hybrid involved in an accident.
In this article, we’ll take a look at disabling the high-voltage electrical systems on vehicles that have been racking up miles on U.S. roads – the Honda Insight and Toyota Prius.
When servicing hybrid vehicles, be wise and prepared, not frantic and scared. Both Honda and Toyota have readily available service precautions that you need to read and carefully follow before you work on one of their hybrids.
Toyota Prius
The first-generation Prius (sold in the United States since 2000) is one that you may see in your shop soon. Some shops may already be providing routine scheduled maintenance to this and other hybrid vehicles.
The Prius uses a high-voltage battery pack that’s comprised of 38 modules. Each of these modules contains six 1.2-volt cells. This is a total of 273.6 direct current (DC) volts.
The DC power emitting from the battery pack is channeled through an inverter that regulates the electric current between the motor generators and the high-voltage battery. It actually converts the DC from the battery pack into alternating current (AC) three-phase power.
This current flows both ways because not only does the battery power the motor generators that move the car, but the motor generators charge the high-voltage batteries when you release the throttle. The braking action of the motor generator when you release the throttle is what charges the battery. So, the vehicle becomes more efficient in stop-and-go traffic.
(Note: The new-generation 2004 Prius has been upgraded with a 50-kilowatt electric motor from the earlier 33-kw version. The Prius nickel-metal hydride battery is upgraded, too, to a 500-volt maximum, up from 273.6 volts.)
Disabling the Prius High-Voltage Electrical System
For ease in identification, any electrical cable that carries the 276-volt current is colored orange. Any orange-colored cable should be avoided until the high-voltage electrical system has been disabled. Insulated gloves rated for 5,000 volts and certified to 1,000 volts must be worn whenever touching any high-voltage part of the Prius.
- Remove the ignition key.
- Disconnect the 12-volt battery.
- Put on insulated gloves, then remove any covers that will impede access to the high-voltage service plug located in the hatchback area of the vehicle.
- Turn the orange service plug lever from the 12 o’clock position down 90