Hybrids bring new opportunities

Although hybrid vehicles currently represent only around 3.5 percent of new car sales, that number is expected to increase consistently in the coming years. That percentage could really explode if fuel prices spike like they did in July 2008. So, whether it’s sooner or later, you’ll eventually need to perform service on a hybrid vehicle.

What basic precautions should I be aware of when servicing a hybrid vehicle?

Let’s start by putting things in the proper perspective. While it’s true that hybrid technology has some new twists when it comes to service, you needn’t panic. For the most part, hybrid vehicles require many of the same services as conventional vehicles. This means most routine services such as oil changes, wheel alignments, brakes, and suspension and exhaust work are pretty much the same as on regular cars. The biggest difference lies in the electrical system, where hybrids have some distinct differences.

Typically, hybrid vehicles use two separate electrical systems. One of these systems incorporates the standard, 12-volt electrical components found in most vehicles. The other electrical system employs the use of high voltage for the hybrid drive. The required voltage for hybrid drive operation can exceed 600 volts. Use extreme caution around any part of the high-voltage system. If not, you could be injured or killed. You can indentify the high-voltage system by warning labels and the bright orange color of the high-voltage cables. Make sure you receive proper training before attempting to service any part of the high-voltage electrical system and its associated hybrid drive. You should also wear appropriate personal protection equipment, such as high-voltage insulated safety gloves and a face shield, when working around the high-voltage system.

Can I use the same digital multimeter (DMM) on a hybrid’s high-voltage electrical system that I’ve always used for other automotive applications?

Absolutely not! Because of the inherent high voltages in the hybrid drive system, you will need to use a meter that meets a standard known as CAT III. This also applies to the meter’s leads. A meter meeting this standard offers the best personal protection when working around the electrical energy potential found in high-voltage hybrid drive systems. By comparison, a standard DMM only meets CAT I or CAT II requirements. Finally, even though a CAT III meter is the right one for the job, it cannot keep you safe by itself. You should only use a CAT III DMM in conjunction with the proper training and personal protection equipment.

Are any special tools required for servicing high-voltage components?

Yes, insulated socket and extension sets are available for additional safety when removing components such as the high-voltage batteries and other key parts.

Will a scan tool help in performing diagnostics on a hybrid vehicle?

Yes, but it really depends on the specific scan tool you’re using. All hybrids incorporate diagnostics into their OBDII system. A vehicle-manufacturer-specific, factory scan tool provides the most comprehensive functionality for hybrid diagnostics, but some aftermarket scan tools can perform some functions. With that said, check with the provider of your current or prospective scan tool to see what kind of coverage it has now, and what’s on the horizon. Since hybrid technology is evolving so rapidly, and so are scan tools, new applications are being released on a regular basis. It may be wise to ask around to see what other techs are using for hybrid scan tools.

What kind of equipment do I use to charge the hybrid drive batteries in a hybrid vehicle?

First of all, let’s make one thing clear: NEVER, EVER attempt to charge the high-voltage batteries in a hybrid vehicle! Not only is it dangerous, it’s unnecessary. Once again, the high-voltage electrical system is clearly identified through the use of warning labels and bright orange cables, so beware!

Can I use my shop’s battery charger to charge the battery in the conventional, low-voltage electrical system?

Maybe, it all depends on the capabilities of your charging equipment. Older battery chargers were built for batteries using conventional, flooded, lead-acid construction. However, most hybrids use a single, 12-volt battery using an advanced design known as valve-regulated lead acid (VRLA). Specifically, it could be an absorbed glass mat (AGM) construction. The newest battery chargers allow you to select the type of battery design when setting up the charger, to establish the proper charge rate. To determine if the battery you’re about to charge has an advanced design, look for labels and markings on the battery such as VRLA or AGM. Always make sure you have the proper battery type selected before turning on the charger. Using the wrong type of charger, or the wrong charger setting, could damage some of the newer battery designs.

If servicing a hybrid is mostly the same (other than the high-voltage electrical system) as a conventional vehicle, are there any things I need to be aware of?

As with servicing any vehicle, you’ll always want to have the most current service information at hand. In that regard, service information is a tool unto itself, so make sure you have a current service information subscription to stay on top of all aspects of service—hybrid or otherwise. Although there are numerous subtle differences we could highlight about servicing non-hybrid areas of a hybrid vehicle, there’s one seemingly minor procedural detail that could cause you a major headache in your shop. It involves performing an oil change on the engine in a Toyota Prius. Basically, make sure the READY light is off before you begin. Why is this so important? If you’re not careful and the READY light is on while performing an oil change, the engine could start up to charge the high-voltage battery. If this happens, it could cause major engine damage due to lack of lubrication. It’s a tale of woe you’d never want to experience, and one you’d be too embarrassed to share. To play it safe, make sure the READY light is off and remove the key from the slot in the dash.

If I should encounter a hybrid with a poor-running engine or one that lacks power, what do I need to troubleshoot it?

In this respect, the internal combustion engine (ICE) in a hybrid vehicle is no different from the one in a conventional vehicle. For that reason, a hybrid ICE is just as susceptible to the same performance-robbing culprits. Perform the usual checks with a scan tool, and the appropriate pinpoint diagnostics with tools such as an ignition or lab scope, fuel pressure gauge, and so on. The basics of engine diagnosis apply the same here, so you should be comfortable working on a hybrid in this respect.

Can a hybrid vehicle be jump-started like a conventional vehicle?

Yes, a hybrid vehicle can be jump-started as long as it uses a single 12-volt battery. Jump-starting can be performed with a battery booster pack or with a host vehicle and conventional cables. Let’s start by assuming the battery’s dead or extremely discharged in the hybrid vehicle.

• Connect the cable clamp from one end of the positive cable to the positive terminal on the hybrid’s 12-volt battery.
• Connect the other cable clamp of the positive cable to the positive terminal of the host vehicle (not applicable if using a battery booster pack).
• Connect the cable clamp from one end of the negative cable to the negative terminal of the host vehicle (not applicable if using a battery booster pack).
• Connect the cable clamp from the other end of the negative cable to a good clean ground on the hybrid vehicle.
• Disconnect the cable as soon as the hybrid vehicle starts.

You may find dedicated jump-starting connectors or “lugs” to ease connection during jump-starting. Not only does this keep connections away from the battery, it also saves you from finding the battery since it can be situated in remote locations (like the trunk.)

As a final reminder, never try to connect to the high-voltage battery or electrical system. If you see warning labels or bright orange cables, stay away! Servicing hybrids is only in its infancy. As technology continues to evolve, and the service industry continues to adapt to this evolution, new tools and techniques are sure to keep pace. Stay tuned to PTEN and we’ll keep you in step along the way.

Send your 'Tool Q&A' questions to editor@pten.com.