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...


A. No, insulation testing is a specific diagnostic test performed using a procedure with a suitable meter having insulation testing capabilities. Put aside everything you’ve previously known about typical low-voltage insulation testing on automotive circuits; when it comes to hybrids, insulation testing takes on a whole new meaning.

Some multimeters have a dedicated insulation test function built into them and are labeled as such. Some multimeter manufacturers combine this function along with more conventional DVOM functions. When combined, this can serve as a great ally when diagnosing problems in a high-voltage hybrid circuit. The need to perform an insulation test usually comes as a pinpoint test on the heels of other diagnostic clues, such as a MIL light on the dash, trouble code, or other hybrid system warning lamp.

When performing an insulation test, you follow the manufacturer’s procedure exactly as it’s spelled out. This includes heeding the manufacturer’s safety rules and deactivating the high-voltage circuit precisely as prescribed. Again, think of these steps as being integral with the service procedure itself; follow each detail to the letter or you may be jeopardizing your safety or even your life. Generally speaking, with the meter’s leads connected as required, you apply a specified voltage with the meter to the high-voltage circuit and then read the resistance value on the meter. Typically, the voltage test value is 500 volts, again applied by the meter, and the specification for resistance will be displayed in megohms (millions of ohms). You then compare the observed reading to manufacturer’s specifications for that test. The test specification varies according to the exact test being performed.

Q. Is there any sort of online resource center where I can find more details on the availability of training, equipment and service information for hybrid vehicles?

A. Yes, the National Automotive Service Task Force on the web at www.nastf.org is a cooperative effort among the automotive service industry, the equipment and tool industry, and automotive manufacturers to ensure you have the information, training and tools needed to properly diagnose and repair today's high-tech vehicles. 

One of the first projects taken on by NASTF was the OE Service Information Matrix. This is a detailed document showing what information is available directly from each car manufacturer including contact phone numbers and web sites where available. This document is continuously updated as new information and resources become available. To help identify gaps in the availability of service information, NASTF accepts feedback from you, the service professional. Any problems locating or obtaining service information through the OE Service Information Matrix may be reported directly to NASTF.    

Q. Can I use a scan tool to diagnose hybrid vehicles?

A. Absolutely, just like with every conventional OBDII-equipped vehicle, a scan tool can be just as much effective when diagnosing hybrid vehicles. This includes the display of trouble codes, self-tests, freeze frame data and more. Hybrid systems often have their own trouble codes and will trip the MIL light on the dash. A fault may also trigger other lamps, indicating a problem. You’ll want to check scan tool capabilities carefully here, as your current scan tool may not be hybrid-capable, or at least not with the current scan tool software.

Just remember that the right scan tool for you depends on the exact hybrid vehicles you plan to service. The landscape of applications is changing rapidly, so check with your equipment rep to determine what options you have available. It also doesn’t hurt to ask around by checking with your fellow techs and shop owners. It just might be worth a post on the International Automotive Technicians’ Network on the web at www.iatn.net.

Q. We run a small shop and want to see how much hybrid service demand there is before we make a large investment. Do you have any business tips for this before we make the plunge?

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