The power inverter is the business end of the hybrid electric vehicle (HEV). This one’s from a Gen 2 Prius. The power inverter takes high-voltage DC current from the battery pack and changes (inverts) it into three-phase AC for the drive motors, A/C compressor and other electrically driven power devices. Notice the three orange high-voltage cables which tell you to keep your hands off.

The power inverter is the business end of the hybrid electric vehicle (HEV). This one’s from a Gen 2 Prius. The power inverter takes high-voltage DC current from the battery pack and changes (inverts) it into three-phase AC for the drive motors, A/C compressor and other electrically driven power devices. Notice the three orange high-voltage cables which tell you to keep your hands off.

In this follow-up to a previous article on hybrid vehicle service, Bob discusses the types of hybrid vehicle repairs being performed by independent shops and how to decide on the kinds of repairs you’ll want to tackle.

In the previous issue of Auto Service Professional, we discussed how the number of hybrid-electric vehicles (HEVs) on U.S. roads has increased exponentially over the last 12 years, and the kinds of vehicles we’ll be seeing in the marketplace. The terms used to describe the various kinds of electrically driven vehicles seen will vary from one manufacturer to the next. You can refer to the accompanying chart for an explanation of the differences between a battery-electric vehicle, a plug-in, and so forth.

In this article we’ll outline what shops are currently doing to diagnose and repair hybrid vehicles, how often, how critical and what basic knowledge, tools and equipment you’d need if you want to get started. We’re talking specifically about servicing HEV high voltage systems. This information is important if you’re thinking about getting into hybrid vehicle high-voltage systems and component service. If you’re serious about keeping your customers (with hybrid vehicles) happy, or just thinking about getting into hybrid-vehicle service, read on.

Are there hybrids in your future?

What do hybrid vehicle Subject Matter Experts (SMEs) consider important?

We think you’ll find the results of the included analysis important to your professional future. In it you’ll discover what other shops have been doing in the way of hybrid vehicle service and repair. See if any of the services described sounds interesting to you. If so, this should help give you direction in deciding your professional future.

Some time ago, the National Institute for Automotive Service Excellence (ASE) decided to sponsor a “Light Hybrid Vehicle Focus Group/Exploratory Workshop” (see sidebar). They invited some of the country’s leading hybrid vehicle OEM and aftermarket trainers and repair shop owners (considered SMEs) to share their opinions about what kind of work they saw being performed on HEVs. The information learned was then entered into a database by ASE staff, and the resulting information is shared in the charts accompanying this article. The SMEs determined that most of the work specific to light-duty hybrid vehicles being done by shops falls into six major areas of repair. These are:

A. Safety and general maintenance;

B. Battery packs [typically high-voltage];

C. Internal combustion engine (ICE);

D. Drive systems;

E. Power electronics;

F. Hybrid [vehicle] supporting systems.

Breaking things down further, within each of the six major service areas, the SME focus group identified various procedures being performed on hybrid vehicles. For each procedure, the group then went on to identify:

• The applicable drive system type (Types 1 through 4 — see previous ASP article in July/August 2011).

• The frequency of repair (i.e. how often the procedure is done).

• The criticality (or importance) of each procedure; and

• Who is doing the repair(s); i.e. the technical knowledge and skill required.

 Some of the country’s best and brightest hybrid vehicle service experts are telling us what they are doing to keep HEVs running. You can benefit from their findings by studying them carefully.

In no particular order, here’s just a sampling of the kind of hybrid vehicle service the best shops are offering:

• Determine if vehicle ICE is in crank mode or run mode.

• Force ICE to enter service mode (disable idle stop).

• Locate and safely disable/enable safety interlock.

• Diagnose and repair HV battery pack heating and cooling systems

• Perform high voltage disable (safe down)/enable (power up) procedure.

• Repair or replace HV battery pack internal components.

• Diagnose AC/DC inverter overheating; determine needed repair.

• Reset inclination sensors.

I don’t know about you, but I find this kind of service absolutely fascinating. If you agree, find out if your local market has the potential to support doing these HEV repairs. Knowing what the experts are doing will likely help you decide what to do in your market area.

The information will also help you get an idea of how much training and tools you’ll need to plan for.

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What to expect

As stated in the previous Auto Service Professional article (Hybrid Part 1), we cannot overemphasize the need for quality hybrid vehicle training commensurate with OEM service standards (we’ll cover HEV training in the next article). Proper training will arm you with needed knowledge. Some systems (and parts) used on hybrid vehicles are not different than those of non-hybrid vehicles; even now you can no doubt service many areas on hybrids like tires, brakes, perform oil changes, etc. Yet even offering common types of service may require some up-front knowledge of HEV operating systems to stay out of trouble.

For example, you may have heard about the lube tech who raised a hybrid vehicle on the lift to change the oil, but left the vehicle’s radio playing. The only trouble was, the lube tech had not disabled the hybrid’s idle-stop feature. Once the vehicle’s 12-volt battery ran down a bit, the engine auto-started to recharge the battery, but the tech had drained the oil from the engine!

The point is: Know what you’re doing! Some hybrid systems are unique and require specific knowledge before servicing.

Despite some hybrid features being similar to non-hybrids, there are also many differences. Many formerly belt-driven components are now electrically driven, such as the A/C compressor, the power steering rack, and the water pump(s). Engine related OBD-II generic fault codes (DTCs) are the same as you’re accustomed to, but you’ll need a quality scan tool to access manufacturer specific data and to delve deeper into HEV fault findings.

You’ll need access to OEM level service information, some of which is available in aftermarket publications. On the other hand, some so-called “hybrid maintenance guides” on the market are nothing more than rehashed general vehicle service information, and even contain some degree of misinformation, so beware.

Hybrid vehicle safety

The matter of servicing hybrids safely will be covered in another article, but for now, know that following OEM safety and service procedures is a must for keeping out of trouble. There are many safety features built into hybrid vehicles to prevent accidental damage and/or injury, but once you decide to venture into high-voltage areas, be prepared to spend some money on safety equipment. This is no time to squeeze the nickel! Some of the standard equipment for HEV service includes:

• OEM or equivalent scan tools;

• A high-quality (3-phase CAT III or CAT IV) digital volt-ohm meter with appropriate HV leads;

• Insulated gloves rated for 1000 volts (Class 0);

• Safety cones and safety tape (to mark off service areas), and more.

If you decide to service the high-voltage areas of hybrid vehicles, stay alert and continually practice situational awareness.

Getting started

Once you’ve decided the kind of service you want to offer to your customers, having the proper training, service information, tools, testing and safety equipment to perform HEV service is a must. Most HEVS run on electric drive systems with several hundreds of volts of potential zapping power (identified by thick orange cables); some HEVs (GM mild hybrids) run on 36/42 volt systems (with blue cables). You’ll need to access factory approved service procedures, vehicle specifications, service bulletins and so on. Valuable hybrid service insights can be found on technician forums such as Identifix and iATN (on the Internet).

Engine related OBD-II generic fault codes (DTCs) are the same as you’re accustomed to, but you’ll need manufacturer specific data in order to delve deeper into HEV fault finding using a quality scan tool. There are scan tools, and then there are scan tools with hybrid diagnostic capabilities. Check with the major suppliers before buying to be sure the scan tool you select will do what you want — such as accessing manufacturer specific DTCs.

For now...

These are indeed exciting times for shop owners and technicians alike, and we hope the information provided in this article will be helpful to you. Be sure to learn more about hybrid vehicles as you browse the Internet. In the next issue we’ll discuss the kinds of hybrid vehicle training available, offer more tips on servicing hybrids safely, and more. In the meantime remember this:

When working on hybrids, keep safety for yourself and those around you foremost in mind. This is NOT the time to rely merely on good luck!

Footnote

1. For diagrams of HEV drivetrain architectures see the July/August 2011 ASP Hybrid Vehicle article. See also the Summer 2008 ASE TechNews article entitled PHEVs Are Coming! at www.ASE.com. Note that most (an estimated 90%) of U.S light-duty hybrid vehicles are Type I.

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ASE focus groups

Most of you are aware of the National Institute for Automotive Service Excellence, or more simply ASE. ASE hosts voluntary technician certification exam sessions and issues credentials to those who pass. But much before a cert test is offered, ASE first hosts focus group meetings of 12-15 subject matter experts (SMEs) to determine:

 • If the market is performing subject-related repairs in sufficient numbers to warrant further study.

• If a sufficient number of experienced technicians exist in the field to sustain a certification exam.

• If a subject-related test could be developed (sometimes, for technical reasons, it is not possible to develop a meaningful test).

• If there exists a market requirement for a certification exam.

• If the industry (trade groups, etc.) will philosophically and financially support the development of an ASE test or test series.

Once it is decided that a certification exam is needed by the industry and would be sustainable, SMEs then meet at so-called Test Development Workshops to determine the essential content areas and need-to-know skills (tasks) required by experienced technicians to successfully perform automotive diagnosis and repair. Indirectly, this information serves the training sector for determining the kind of training needed by service technicians for performing successful vehicle and equipment repairs. Once the SMEs have developed test specifications and task listings (aka competencies), they set to work writing actual test questions to address the aforementioned competencies/tasks. The test specifications for every ASE exam are available on ASE’s Web site.

The hybrid vehicle diagnostic and repair information cited in this article was determined by light-hybrid-vehicle SMEs who attended an ASE sponsored fact finding workshop held in October 2009. Data and charts developed during the meeting are provided here courtesy of ASE.

Terms you should know

There seems to be some confusion when it comes to classifying hybrid vehicles. In the last article we classified HEVs by the type of drive configuration used, such as planetary gearsets, multiple electric machines, CVTs, etc. That said, it would also be good to distinguish between the types of “electrically” driven vehicles. NOTE: These designations are thrown around with abandon. Don’t be surprised if vehicle advertising literature uses other names for these vehicles.

BEV = Battery Electric Vehicle.

BEVs need recharging when batteries are low. Lead acid or nickel-metal hydride batteries were typically used; now lithium ion and other types of batteries are used for greater range. Early BEVs include GM’s EV-1, Ford’s EV Ranger, Toyota’s RAV-4 EV and Nissan’s Altra. Most of these early EVs have been reclaimed and scrapped by the OEMs. Now, a whole new generation of EVs are becoming available, such as the Nissan Leaf. Watch for more in the not-too-distant future.

HEV = Hybrid Electric Vehicle.

HEVs have two power sources, typically a gasoline ICE and HV batteries working in both series and parallel. HEVs are not typically electric grid rechargeable, although some have been converted to PHEVs (see below) for over 100 mpg. HEVs range from micro, to mild or blended, partial and full hybrid vehicles.

• GM’s Silverado and Sierra with start/stop features were considered micro hybrids

• Honda’s Civic and Insight are partial hybrids – the engine (ICE) does not shut off while the vehicle is underway.

• Toyota Prius and Ford Escape/Mercury Mariner hybrids (and many others) are considered full hybrids as they can be driven short distances and at low speeds using only the (high-voltage) batteries.

PHEV = Plug-in Hybrid Electric Vehicle.

A PHEV-20 can go 20 miles before the batteries need charging; a PHEV-40 can go 40 miles, etc. An ICE may start up for added power or when the batteries need a recharge. The Tesla PHEV is on the market. Ford, Toyota and other light duty vehicle OEMs have PHEVs on test. Medium duty vehicles from Fed-Ex, UPS, Mercedes Benz and others offer PHEVs for commercial use. International Truck and Engine sells a PHEV school bus.

EREV = Extended Range Electric Vehicle.

These plug-ins have a relatively small auxiliary ICE to drive a generator for charging the batteries. The Chevrolet Volt is a series EREV.

FCV = Fuel Cell (electric) Vehicle.

FCVs are technically to be considered hybrid vehicles because they have two power sources. These would be typically a hydrogen fuel cell “stack”, and a storage device from which to draw electric power. Regenerative braking electrical energy may be stored in the vehicle HV battery pack, or as with Honda’s early FCX and others, in ultra/super-capacitors which can more quickly be charged or provide acceleration power as needed.

(See the September/October 2011 issue of Auto Service Professional for complete charts and photos.)


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