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Hybrid and Electric Vehicle Service

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Hybrid and Electric Vehicle Service

This year, the Corporate Average Fuel Economy (CAFE) standard for passenger cars increased for the first time in decades, from 27.5 mpg to 34.1 mpg. By model year 2025, the CAFE standard will increase again to 54.5 mpg.

To reach these fleet average numbers, almost every automaker selling cars in North America has already introduced at least one model with a hybrid-electric or all-electric powertrain, and they are all working hard to increase the market as well as develop the technology.

The hybrid fleet is expected to grow dramatically over the next decade, and the odds of a hybrid car pulling into your driveway are increasing each month. If you’re not already working on hybrid or plug-in vehicles, it’s the time to prepare for some new service opportunities.

Normal maintenance of a hybrid car is not much different from a conventional vehicle: it has an engine, so it still needs a periodic oil change and a new air filter and eventually new spark plugs, too. Pure electric vehicles don’t have an engine, but just like hybrids, they still need new cabin air filters and wiper blades, brakes, shock absorbers, and of course tires. But before you agree to service a hybrid or electric car, there are some things you need to know that will help you decide which maintenance services you want to offer, and some things that are important to the safety of your technicians and your customers’ cars.

Specific oil change recommendations

One reason hybrids get such good gas mileage is because they almost never get zero miles per gallon. Unless the engine is charging the battery or running the air conditioner, it automatically shuts off whenever the car stops moving.

This stop/start feature confuses most first-time hybrid drivers because they think the car has stalled. Many are also surprised when the car starts moving again once they release the brake, even if the engine is not running. When techs drive hybrids into the shop and the engine stops, they quickly figure out that the shift lever must be in Neutral or Park to prevent the car from moving.

What some techs don’t figure out right away is how to make sure the car is turned off, especially since most hybrids have a Stop/Start button instead of an ignition key. If the car is turned on, the engine will start when the battery’s state-of-charge falls below a pre-programmed percentage. The only way to prevent this is to make sure the car is turned off and the gauges and display screens are all dark. Imagine the horror of hearing the engine start with the car on the lift and the oil drain plug removed (it has happened).Every car manufacturer recommends the type of motor oil that should be used in their engines, and those recommendations are quite specific for hybrids. Most are designed to use 0W-20 motor oil, and if heavier oil is used it will decrease the car’s gas mileage. This will make your customers unhappy (they pay close attention to gas mileage), and it also can have more serious consequences. For instance, if heavier oil is used in a third-generation Toyota Prius (2009-2015), the timing chain tensioner won’t pump up properly. The timing chain will rattle and maybe even jump a tooth, which would cause serious engine damage.

Using the correct quantity of oil is also critical on a hybrid vehicle. Excess oil increases the amount of oil fumes drawn into the Positive Crankcase Ventilation system (PCV), and those fumes flow past the engine’s airflow sensor. If the sensor becomes fouled with oil, the Powertrain Control Module (PCM) will turn on the Check Engine light. Since the engine is already running when the fault is detected, the PCM on conventional cars will substitute different data to operate the engine, but on most hybrids the PCM won’t even start the engine if that sensor isn’t working properly.

Brake system service

The brakes on a hybrid or electric vehicle often require replacement long before they wear out. To understand this, and to understand the service opportunities available to you on these vehicles, it helps to understand regenerative braking.A Direct Current (DC) motor is the same thing as a DC generator; the only difference between them is the direction of current flow. A hybrid vehicle has at least one motor/generator..

When the brake pedal is pressed, the PCM switches the current flow, turning the motor into a generator that is driven by the motion of the car.

Even though the car is slowing down, much of the energy that was used to put the car in motion (kinetic energy) is recovered and stored in the battery as electrical energy. This is called “regenerative braking,” and it’s the main reason hybrid vehicles get such good gas mileage: energy is recovered instead being converted to heat by the brakes and simply dissipated into thin air.

So when you press the brake pedal on a hybrid or electric vehicle, the PCM uses the generator to slow the car. It could actually stop the car completely, but generators work unevenly at low speeds and the last few yards of deceleration would be very jerky. So at about 5 mph, regenerative braking ends and the PCM finally applies the hydraulic brakes. That means in normal driving the brakes are hardly ever used and never used at speed, so they never get hot.

As a result, seized calipers and rusted brake rotors are common on hybrid and electric vehicles, especially in rust belt states. It’s also common for brake pads to delaminate or be stripped off the backing plate. This is why pads, rotors and sometimes even calipers need to be replaced long before the brake pads actually wear out.

Before starting brake work on any vehicle with a computer-controlled brake system or electronic parking brake (hybrids are not the only vehicles with brake-by-wire), it is absolutely critical to make sure the system is completely deactivated. Some of these systems run a full-pressure self-diagnostic test while the car is turned off. If this happens with the pads removed, it will damage the system and/or injure the technician.

On some cars, deactivating the brake system is as simple as manipulating the ignition key and brake pedal in the proper sequence, while on other cars it must be done with a scan tool. A scan tool may also be needed for bleeding the hydraulic system. Not all scan tools have the necessary capabilities, so make sure you have the proper equipment and complete service information before accepting a brake job.

Low-rolling-resistance tires

Even if you’ve never sold tires for a hybrid or electric vehicle, you probably already know they use special low-rolling-resistance tires. Most of a tire’s rolling resistance comes from the energy that’s needed to deform it at the bottom as it flattens into a contact patch. The remaining resistance comes from tread squirm. To reduce that energy requirement, low-rolling-resistance tires use different rubber compounds and different construction. They also tend to be lighter than conventional tires and have shallower tread depth.

Like every other tire in the world, low-rolling-resistance tires are a compromise between ride quality, handling and tread wear, but most hybrid drivers care more about the tire’s energy efficiency rating. General Motors Corp. says a tire can impact fuel economy by 4% in the city and 7% on the highway, and they’re investing heavily in on-going tire energy efficiency research. While the U.S. still has no energy efficiency rating for tires, some other countries do and so do some of the tire manufacturers. If your customer has already done his own research, he will know which tires have the best rating.

However, don’t be surprised by hybrid owners who are happy to exchange a bit of gas mileage for better handling. As you might imagine, low-rolling-resistance tires are not performance oriented, but some hybrid vehicles are a lot of fun to drive when pushed hard, and those customers may opt for a more performance-oriented tire.

When new low-rolling-resistance tires are installed, make sure to tell your customer they may notice a reduction in gas mileage, otherwise they’ll come back asking what you did to their car. As tire tread wears down, rolling resistance can decrease by as much as 20%, so the customer’s gas mileage will gradually improve as the new tires wear.

Battery service on hybrids and electric vehicles

All hybrid and electric vehicles have a 12-volt electrical system, and most of them also have a 12-volt battery. The 12-volt system is used for all the standard automotive equipment like lights and wipers, and it also powers all the electronics and control systems, including the Powertrain Control Module.Even though almost all models (except most Hondas) use the high-voltage battery to start the engine, the car won’t even turn on if the 12-volt battery is dead. It’s imperative for this battery to be checked any time the vehicle is in for service. Since it doesn’t get stressed by the starter, the driver never hears the one clue that we all rely on to warn us of a worn-out 12-volt battery: slow engine cranking speed.

The only service needed for the high-voltage battery on a hybrid vehicle is to make sure the battery cooling system is working properly. Many models have a separate cooling fan for the battery pack, and some have an air filter on the fan duct that should be changed along with the cabin air filter. On several models the battery pack is cooled by the vehicle’s air conditioner, which means the A/C might run even if the driver has not turned it on. It’s important to make sure the evaporator drain tube is not clogged.

Safety considerations for hybrids and electric vehicles

Although normal service work on a hybrid or electric vehicle can be done without disturbing its high-voltage system, that system carries enough voltage to cause fatal injury. If the car is completely turned off, such injury is extremely unlikely, but disabling the system is usually required for insurance coverage (not to mention peace of mind), and it is exceptionally simple to do.There is a plug or switch on or near the battery pack itself that completely disconnects the high-voltage battery from the entire high-voltage circuit without disabling the 12-volt system. Honda Motor Co. Ltd. uses a simple on-off switch that looks just like a household circuit breaker. Most other manufacturers use a plug that you simply unplug or actually remove from the battery pack.

One note of caution: When the disconnect plug is removed, it can easily be lost. Most techs put it on the dashboard so it can be seen through the windshield. That way everyone can see that the high-voltage system has been disabled and no one will try to drive the car with the plug removed.

Finding the location of the disconnect plug can be a challenge. They’re commonly in the trunk or behind the rear seatback, but they can be anywhere on the vehicle. If you can’t find information on where and how to disconnect the high-voltage battery in your service information system, search the car manufacturer’s website for a section called “First Responder Guide.”Insurance and safety regulations require the use of lineman’s gloves when removing or installing the service disconnect plug. These are rubber gloves with rolled cuffs that are Class O and rated to 1,000 volts. They should be kept in a bag that protects them from sunlight and damage, and while they can last almost indefinitely with proper care, they should be inspected twice a year by the manufacturer. In order to prevent damaging the gloves on sharp edges, leather gloves should be worn over the lineman’s gloves.

If your shop offers repair services and you see lots of hybrid vehicles in the neighborhood, it’s time to consider sending a tech for training. Hybrid repairs aren’t any more difficult than other cars, but they are different. There are some excellent hybrid training courses available, and you can find them just by searching the Internet.

With an ESVE charger out front and a technician training certificate on the wall, your hybrid customers will know you’re serious about taking care of their cars. And as the fleet grows, so will your customer base.  

Not built for speed: High-voltage hybrid batteries charge slowly

As plug-in hybrids and rechargeable electric vehicles become more common, there may be times you need to charge the high-voltage battery. These cars all have an on-board system that converts the alternating current (AC) from a regular 110-volt outlet into the direct current that charges the battery, but it’s a slow process. One hour of slow charge provides only about 10 miles of driving range.

An Electric Vehicle Service Equipment (ESVE) connection that supplies 240 volts to the car’s on-board charger will cut the charge time in half, and a real DC battery charger reduces even that time by half.

A DC charger is service bay equipment, like a Toyota dealer would use to charge a Prius battery. I’ve never seen one, but I know they’re not generally available for or used in aftermarket service because they tend to be manufacturer-specific. If a shop specializes in one make of hybrid vehicle, say, Honda, it might pay off, otherwise it would hardly be used at all.

It might not make sense to install a DC charger, but commercial ESVEs are not expensive, and placing one in your parking lot is a good way to attract new customers.

Jacques Gordon has worked in the automotive industry for 40 years as a service technician, lab technician, trainer and technical writer. He began his writing career authoring service manuals at Chilton Book Co., and writes for Modern Tire Dealer’s sister publication, Auto Service Professional. He currently holds ASE Master Technician and L1 certifications and has participated in ASE test writing workshops.

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