Fix It, Don't Fear It

High-voltage wiring in hybrids is becoming a common shop concern.

Toyota Service Training Supervisor Chris Peterson teaches dealer technicians about new electrical safety procedures on Toyota's growing group of hybrids that run on 200 to 300-volt battery packs. He shows how the higher voltage systems work and how to safely service them, though he says explaining exactly why things must be done a certain way is critical when educating technicians.

"That's why we do a three-day training class," Peterson says. "A lot of times you can tell somebody, 'Go do A, B and C,' (but) if they don't understand why they are doing A, B and C, they may down the road decide, 'Ah, I don't need to do B, it's not a big deal.'"

Peterson recommends specialized training for any tech preparing to work on vehicles with orange high voltage cables.

"There are a couple hundred volts in the circuit you need to know how to handle when it's time to disconnect those orange cables," he says.

Voltages vary between models and years of Toyota's hybrids, so Peterson tells his technicians to familiarize themselves with whichever they are working on—but be wary of those orange cables.

"You can do anything you want on the car… basically until it's time to disconnect an orange cable—then you need to be trained on how to disable the system," Peterson says. "The biggest thing is not to be afraid of the car—there are quite a few redundant safeties built into it, so it's a fairly simple car to work on."

Even a simple vehicle can cause problems, though. If a technician working on a quiet-running hybrid does not know it is still on, problems can ensue. A hybrid could be running silently, slowly draining its batteries until the gas engine kicks in at just the wrong time.

"To a lot of technicians... if they don't hear the engine running, it's off," Peterson says. "The hybrids we sell have a ready light on the dash, so when you get in and start the vehicle, there is no cranking sound, it basically turns on the ready light. If you're going to do any kind of service work to it, you've got to make sure that ready light is turned off, because it could be silent. You could be out there popping the drain plug to drain the oil out, or heaven forbid working under the hood and it could still be on and the gas engine could start."


Knowing about the system is important, but what do your technicians actually have to do differently when working on these higher-voltage gas-electric hybrids? Aside from those orange cables, Castiaux says everything else is about the same.

"You're going to have all the same problems you'll have on regular vehicles, because they still have gasoline engines with filters and oils," he says. "On top of that you may have electrical problems, usually related to batteries."

He says that when these hybrids start to age, though, techs could have to deal with other unforeseen problems.

"When these cars start turning 15-20 years old down the road, where maybe some terminals get loose and things like that, they may come up with some quirky little problems they're not seeing now," he says. "Other than electrical problems, I don't know what they'd see different that they don't already see."

Castiaux says technicians that take care of gas-electric hybrids may need some extra shop equipment, depending on the vehicle model. Honda, for instance, has an electric motor-pulling tool that pulls the motor rotor out, avoiding damage.

"There doesn't seem to be a big host of tools I've seen," he says. "There's just not much to wear out in an electric motor."

A high voltage battery can go dead, however. Castiaux says that in most Honda products, for instance, you can still start on the regular 12-volt system and get it into the nearest shop for repairs if the high-voltage system fails.

"Some of the other hybrids, when high-voltage goes bad, you call the tow truck, because only the dealers have the capability to recharge those batteries if they're rechargeable," he says. "It's not anything you and I can put jumper cables on and jump—you do not want to attempt that."

It all comes back to those orange cables. Castiaux says technicians need specific electronics training to safety navigate those systems.

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