Handling hybrid repairs

Servicing hybrids requires a commitment to keeping up with the pace of evolving technology

A: Always proceed with caution when working around the electrical system. Generally, the 12-volt, low-voltage part of the electrical system will use red and black to represent positive and negative polarities, respectively. Blue or yellow cables typically signify circuits with a somewhat higher voltage of 42 volts. Although 42 volts does not present a shock hazard, its circuits can cause arcing when opened. Finally, and most importantly, orange cables along with accompanying warning labels signify high-voltage circuits, ranging from 100 to 600 volts or more. Failure to exercise caution around high-voltage circuits can cause injury or death, so be careful.


Q: What kind of battery charger should I use to charge the high-voltage battery in a hybrid?

A: In normal use, a dedicated vehicle module takes care of the charge in the high-voltage battery. While it’s true that specialized high-voltage chargers are available, especially in the dealer network, your best bet is to make sure the hybrid ICE gets started, and let the battery module and the rest of the hybrid high-voltage system in the vehicle itself take care of charging the high-voltage battery.


Q: We’re hesitant to jump into hybrid service because we’re uncomfortable with working around the high-voltage electrical system. What kind of safety measures can I put into place to protect my technicians?

A: First, invest in technician training for all your staff who will be working on the high-voltage electrical system. Remember, the overwhelming majority of hybrid vehicles still require many of the same maintenance procedures as a conventional vehicle, and don’t involve the high-voltage circuit at all. For those planning on servicing the high-voltage circuit, they should wear insulated rubber gloves, similar to those worn by utility linemen. The gloves should be rated to a minimum of 1 kV (1,000 volts), and carry a class 0 designation by ANSI and ASTM.


Q: Are there dedicated testers for taking voltage readings in a hybrid’s high-voltage electrical system?

A: You bet. The voltages found in the high-voltage electrical system of a hybrid require that you use a meter and leads meeting a CAT III standard. A meter meeting this standard, rated at 600 to 1,000 volts, offers the best personal protection when working around the electrical energy potential found in high-voltage hybrid drive systems. Do not use a conventional multimeter intended for low-voltage circuits or you may suffer severe shock and related injuries.


Q: When performing cooling system testing on a Toyota Prius, we’d like to disable the idle stop mode to ensure continuous mode operation of the cooling system. Is there a way to do this?

A: Yes, you can use a Toyota Diagnostic Tester to disable the idle stop mode. If you have a different scan tool, check with the manufacturer to see if this capability can be added through a software update.


Q: We run a towing company and work in conjunction with emergency crews at the scene of a vehicle accident. What special considerations apply when first responders appear on the scene of an accident?

A: This is a great question, because hybrids demand special handling due to their high-voltage electrical system. There are special training programs for these scenarios, as we highly recommend you take all the training you can to ensure your safety and to provide the best assistance you can at the scene. While the specifics of individual training programs differ, there are some general guidelines that can be followed at the scene:

• Identify whether the vehicle is in fact a hybrid.

• Disable the vehicle using a manufacturer-approved procedure.

• Secure the vehicle to prevent movement.

• Access the occupants using one or more methods to ensure their safe removal.

• Turn the ignition off.

• Open the 12-volt circuit by disconnecting or cutting the battery cables. Please note that providing first-responder assistance requires the use of manufacturer approved/recommended equipment that requires special training.


Q: Are there any special considerations that need to be made when jacking or hoisting a hybrid vehicle?

A: Like any vehicle, look up the recommended lift points for that specific make and model beforehand. Then, when positioning the jack or hoist, watch for any high-voltage cables that may run along the undercarriage of the vehicle. As an example, some Honda hybrids encapsulate high-voltage cables in a bright orange jacket that runs fore and aft along the unibody. Steer clear of this or you’ll be asking for trouble.


Q: One of my techs says we need to depower the high-voltage electrical system on hybrids whenever we perform service. Is this true?

We Recommend