Toyota has produced a list of recommended procedures technicians need to be aware of when working any of its vehicles that contains a high-voltage battery.
The best practices, spelled out in an article recently published on the Toyota Genuine Parts website, apply to any electric vehicle (EV), plug-in hybrid electric vehicle (PHEV), fuel cell electric vehicle (FCEV) , or hybrid vehicle (HV) produced by Toyota.
Repairers looking to estimate, diagnose or repair one of these vehicles are directed to Toyota’s Technical Information System (TIS) website, techinfo.toyota.com/, for “the assets that will help you get up-to-speed on these high-tech vehicles,” the article says. “In many cases, Toyota has a repair bulletin that outlines how to protect yourself during repairs and provides precautions that need to be taken before the inspection and service of the high-voltage circuit.”
Among particular interest, Toyota said, are procedures related to safely disarming the high voltage systems, and the additional refinishing time these vehicles may require.
Always remember that safety comes first, no matter which type of vehicle or battery is being worked on. “Always do your research and take the appropriate precautions before working on one of these sophisticated vehicles,” Toyota advises.
Any time a vehicle with a high-voltage battery has been in a collision, there’s a chance that the battery and its contents have been compromised, raising dangers of fire and electrocution. Toyota recommends that, after a crash, all high-voltage batteries be treated as though they are unstable, as a precaution.
What follows is the OEM’s list of recommendations:
Repairers should always read the appropriate bulletin for the vehicle they are repairing before beginning work, to check for additional guidelines and cautions.
If a vehicle is to be stored for 30 days or more, Toyota recommends that the shift lever be in the “park” position, and all lights, accessories, and the hybrid system be turned off before disconnecting the negative terminal of the 12-volt auxiliary battery.
If an auxiliary battery must be recharged, Toyota recommends using a battery charger designed for the job, with microprocessors that can vary the charge rate based on the battery’s needs. This can prevent damage to the battery caused by high current rates. Special Service Tool (SST) GR8 Battery Diagnostic Station is the Toyota specified battery charger designed for charging auxiliary batteries.
For proper handling and charging of hybrid vehicle auxiliary batteries, see Toyota Technical Service Bulletin TSB-0043-16, found on TIS.
In use, the auxiliary battery is charged by the high-voltage battery. If the auxiliary battery is low on charge, you may use a jump box to “ready” the vehicle and allow the onboard charging system to restore the 12-volt battery to its ideal level.
As with internal combustion engine (ICE) vehicles, the 12-volt auxiliary battery must be disconnected before any welding is done, Toyota cautions.
“The most significant reason to disconnect a vehicle battery before the repair is to protect yourself and the vehicle’s electrical systems, especially while welding,” Toyota said.
“A 12V battery needs to be disconnected, essentially taking off-line all circuits and connected components to protect them when welding on the vehicle,” cautions Mike Anderson of Collision Advice. “In addition, the main SRS ECU (Electrical Control Unit) wire harness should be disconnected and any ECUs within 18-inches of weld locations removed. These extra steps help prevent the potential for accidental airbag discharge and damage to ECUs from induced welding current.”
The Toyota Mirai is powered by a hydrogen fuel cell system, in which hydrogen from the fuel tank reacts chemically with air coming in from the intake grille to create electricity. The electricity powers an AC motor that drives the rear wheels.
Toyota cautions that before starting repairs on a Mirai, an FCEV-Qualified Toyota Dealership and Technician must be consulted to assess the damage to the hydrogen fuel system components: the fuel cell stack, fuel system piping, receptacle, tube joints, sensors, regulator, and tank assemblies.
The precautions for other EVs and HVs apply to the Mirai, with the added consideration of the compressed hydrogen gas stored in high-pressure tanks. The hydrogen must be released to removing the tanks from the vehicle. Toyota directs repairers to have an FCEV-Qualified Toyota Technician help with releasing the hydrogen.
The Mirai has been produced in very limited numbers. In calendar year 2021, just 2,629 were sold in the US.
On the I-CAR website, you will find links to other OEM-specific information, compiled by I-CAR’s Repairability Technical Support (RTS) team. You’ll also find a number of other general EV-related information, including I-CAR’s comprehensive best practice on HV disconnection, as well as technical articles written by I-CAR experts.
The documents within the best practice include:
Featured image provided by Toyota.
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