Some quick tips on the basics of one of the most common hybrids on today's roads -- Prius.
Those who were working in the automotive repair industry in the early 1980s will recall the beginnings of a revolution in automotive computer control. We look back now and almost laugh at the relative simplicity of those early systems. While many embraced the new technology as it was introduced, others hoped it would go away and did what they could to avoid it.
Now, of course, there are few functions on a modern automobile that are not controlled by a computer. Folks who made the decision to keep up with the times survived, and ultimately prospered.
Automotive computer control has almost three decades of history behind it, and has been woven into the fabric of the repair culture. Looking down the road, the time has come to prepare ourselves for what could be the next great revolution in automotive technology: the transition from mechanical drive to electric drive. And the best evidence that this transition is well under way is the popularity of the hybrid-electric vehicle (HEV).HEVs have been in the U.S. for 10 years, with the Honda Insight going on sale in 1999 and the first-generation Toyota Prius following in 2000. While these cars made an instant splash in the automotive world, sales were mostly confined to "early adopters." It wasn't until the second generation Prius was introduced in 2003 that sales started to take off and the average consumer began to take the hybrid car seriously.
You might say that the aftermarket repair industry has given a similar sort of reception to HEV technology. A few embraced it early and jumped in with both feet, while a good many others had to be convinced that this idea was going to stick before they would invest in training and equipment. HEVs are not going away, and the technology that has been pioneered on hybrids will continue making its way onto conventional vehicles in coming years. An example of this is electric-assist power steering, which has been commonplace in hybrids but now is being offered in many non-hybrid models as well.
It turns out that HEVs have enough in common with conventional vehicles that you can start doing basic hybrid maintenance with a minimal investment. This would be the first step before taking on more specialized hybrid system repair.Where to start
Think about what hybrids you most often see in your area. Which model do you get the most calls on? In all likelihood, the second generation (model year 2004-09) Toyota Prius will be at the top of your list, as it represents one-half of the entire hybrid market in the U.S. With several model years now off-warranty, opportunities abound for aftermarket repair shops to increase their revenue by performing routine maintenance and repair on those systems shared by their "gas only" counterparts.While the Prius has a good deal in common with conventional vehicles, it has enough unique features that even a savvy technician will require at least an orientation before attempting service on it. For the remainder of this article, here are just a few of those features to be aware of on the second generation Prius.
Starting a Prius
Starting a Prius can be a challenge if you haven't done it before. You will notice that there is a POWER button on the dash, and there is also a slot in the dash for the electronic key. Keep in mind that if the vehicle is equipped with a Smart Key, it does not have to be in the slot to make everything work. It only has to be in the general vicinity for you to be able to unlock the doors and start the car, so you can leave it in your shirt pocket if you like.To start the car, you must hold down the brake pedal and then push the POWER button once. The car will then cycle through its prechecks and turn on the READY light when it is OK to drive. If you push the POWER button without pressing the brake pedal, the car will go into accessory mode (the power button indicator light will be green), leaving the hybrid system turned off. Another push of the POWER button will put the car in the IGNITION ON mode (the power button indicator light will be amber). One final push of the button turns the car off.
The status of the READY light is critical when servicing the Prius. Make absolutely sure that the vehicle is powered down and the READY light is off before attempting any service on it. Remember that when the READY light is on, the Prius can go from electric (quiet) mode to suddenly starting its engine without notice. This could mess up your day if, for example, you have just drained the oil out of the engine.
IMPORTANT SAFETY NOTE: To prevent an accidental start, be sure to keep the Smart Key at least 15 feet away from the vehicle during service. Another way to deal with this is to press the KEY button underneath the steering column. With this button down, the Smart Key is disabled and the key would have to be inserted into the slot in the dash in order to start the car. If the Prius is going to be parked for awhile, it is highly recommended that the Smart Key be disabled to limit battery drain. (Editor's note: Always refer to your service information for the proper safety procedures associated with any hybrid you intend to service.)High Voltage System
All HEVs have a high voltage (anywhere from 36 to 330 volts) battery pack onboard. While lithium-ion is in the works, the dominant battery technology thus far has been nickel-metal hydride (NiMH). The voltage ratings of these battery packs will vary with the type of hybrid in which they have been installed. The rule of thumb is that the higher the voltage, the "stronger" the hybrid. The Prius is considered to be a strong hybrid, because it can move the car from a stop in all-electric mode. It also sports features such as an all-electric A/C compressor, which needs some special attention during A/C service.
The Prius' high-voltage (201-volt) battery pack is located behind the rear passenger seat. There are orange-colored cables connecting the battery pack with the inverter assembly under the hood, as well as between the inverter (the component used to convert battery DC voltage to AC and vice versa) and the two motor-generators in the transaxle. These components should all be treated with respect. To be on the safe side, follow the procedures outlined in your service information on isolating the high-voltage system before servicing. Be aware that the high-voltage cables will not always be readily visible under the car, making the use of the proper lift points essential to avoid damaging them.One area of the high-voltage system that will require periodic maintenance is the cooling system for the inverter and motor-generators in the transaxle. Prius uses liquid-cooling for these components, and this system is separate from the engine cooling system. The coolant is the same as that used for the engine (pre-diluted Toyota Super Long Life Coolant or SLLC) and should be changed at specified intervals. The drain for the inverter cooling system is located on the bottom of the transaxle. Because of all the loops and bends in the system, it is easy to trap air when installing the new coolant. In order to prevent airlocks and overheating of expensive high-voltage components, it pays to use a vacuum-powered airlift tool when refilling.
Engine Cooling System
As mentioned previously, the engine cooling system is separate from that used to cool the inverter. It has all the attributes of a conventional cooling system, but includes a unique emissions-fighting feature that you will find only on the second generation Prius.Prius has a heated coolant storage system that is used to preheat the cylinder head prior to a cold start. A stainless steel coolant storage canister (constructed similar to a thermos bottle) is located behind and below the driver's side headlamp. The system includes a water-routing valve and an electric pump that are used to circulate the coolant. Toyota recommends disconnecting the electric pump during coolant service to make sure there is no possibility of the pump turning on when you have the system open.
Also, be sure to open the valve on the bottom of the canister to allow for a thorough drain of the used coolant. The canister is capable of keeping coolant hot for up to three days, so use caution when draining the system. Like the inverter cooling system, refilling works best when you use an airlift tool.
HVAC System Service
We can't leave you without mentioning HVAC service on the Prius. The A/C compressor is not belt-driven; instead it uses a high-voltage three-phase AC motor. The advantages of this design are significant in regards to fuel economy, as the engine can remain off even while the A/C system continues to operate.However, the system uses unique compressor oil that prevents electrical leakage and will be damaged if ordinary PAG oil is installed. A 1 percent contamination of the existing system is enough to cause problems. Even if you're just replacing a leaking seal, your Recovery, Recycling, Recharging (RRR) machine has enough PAG in its plumbing to contaminate the system and cause a costly comeback. Only recover/recharge with a dedicated machine or one certified (or retrofitted) to upcoming SAE standard J2788H. While the required oil is extremely expensive, it is still cheap relative to a ruined A/C system.
Final Word
If you have been sending your hybrid customers to other shops, now may be the time to start taking in basic hybrid maintenance work. After all, they all need oil changes, tune-ups, brake work and other similar services. As you become familiar with these cars, you may decide to make the investment in further training and equipment to do more advanced repairs.
With more hybrids on the road each day, this will increase your customer base and ultimately, your profits.
Tony Martin is an assistant professor of automotive technology at the University of Alaska Southeast in Juneau, Alaska. He holds Canadian Interprovincial status as a Journeyman Heavy Duty Equipment Mechanic. He also has 18 ASE certifications, including CMAT, CMTT, L1 and L2.
