Hybrids: What's the difference in repairs?

It seems like everyone’s talking hybrids these days, but they’ve already been around for over ten years. With all the focus on reducing greenhouse gases and gasoline prices creeping upwards once again, hybrids seem to be the right “powertrain...


It seems like everyone’s talking hybrids these days, but they’ve already been around for over ten years. With all the focus on reducing greenhouse gases and gasoline prices creeping upwards once again, hybrids seem to be the right “powertrain fashion” for more and more motorists. What does that exactly mean to you as a technician or shop owner? Read on.

Q. We’ve performed basic service on several hybrid vehicles, but we’re unsure of the volume or sophistication of repairs heading into the future. How do we plan for this?

A. It’s an excellent question and one that doesn’t have a singular answer. First, it depends on whether you’re a dealer or independent repair shop. Dealers are sure to see the initial volumes of hybrid service. As an independent shop, you have to consider whether you want to go beyond basic service and delve into system diagnosis and repair. This is a decision not to be taken lightly as safe and proper hybrid service should only be performed with the right combination of training and equipment. And, since the high-voltage electrical system of a hybrid vehicle may operate at voltages up to 650 volts, we can’t over emphasize the importance of proper safety measures during service.

Q. Our shop has decided to take the plunge and get into hybrid service, including diagnosis of the electrical hybrid drive system. What kind of equipment do we need to get started?

A. Before we address the equipment side of things, we need to stress training as the most critical first step. All procedural training for hybrid service should always be presented in the context of maximum safety due to the high voltages present. Potentially dangerous voltages exist at the high-voltage cables (usually colored bright orange), the high-voltage batteries, the inverter-rectifier capacitors, and the electric motor-generator. With that said, the minimum equipment you will need includes a CAT III or CAT IV meter rated to 1,000 volts, rubber insulating gloves and a pair of leather over-protector gloves. Rubber insulating gloves should have a Class 0 rating, meaning they have the capability of insulating the user up to a maximum of 1,000 volts. These gloves should be inspected before every use to make sure there are no pinholes capable of leaking electricity. The leather, over-protector gloves should always be worn over rubber insulating gloves to protect them from damage such as punctures and cuts from sharp edges.

Q. I’ve got an older digital multimeter that’s rated at 10 megohms input impedance. How does this specification correlate to the CAT III or CAT IV meter specifications I’ve been seeing for hybrid testing?

A. Input impedance and CAT ratings don’t correlate at all. Input impedance refers to a meter’s internal resistance, an important factor so as not to overload electronic circuits.

CAT ratings, on the other hand, refer to a standard that defines safety levels by categories for electrical meters. A meter’s CAT rating, ranging from CAT I through CAT IV, represents a meter’s capacity to withstand voltage extremes and transient voltages. Generally speaking, a CAT IV meter has better capabilities to withstand voltage extremes than a CAT I meter. Yet, there’s more to it than just the CAT ratings themselves. A CAT rating must be combined with a voltage specification to be meaningful. For example, a CAT III meter with a 1,000-volt rating is a safer meter than, say, a CAT III meter with an 800-volt rating. The bottom line is, when shopping for a meter to be used around high-voltage hybrid electrical systems, look for a meter with at least a CAT III or CAT IV/1,000 volt rating. The meter’s leads should also have the same CAT rating as the meter itself.

Q. The hybrid vehicle service training we’ve been considering covers a topic called “insulation testing.” Is this simply a physical inspection of the high-voltage cable insulation?

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