Can hybrid and electric vehicles be dangerous to work on? Absolutely. However, if you get proper training and follow OEM repair procedures, you can service and repair them safely and efficiently. Here are a few manufacturer-specific hybrid safety tips that will help you do just that.
Replacing Brake Pads Safely
A lot of techs are apprehensive about replacing brake pads on a Toyota Prius – and with good reason – these brake jobs can be dangerous and tricky to accomplish correctly. But if you know the precautions and procedures before you start, it can be as safe and routine as any other brake job.
- Before you even remove one lug nut, disconnect the 12v auxiliary battery. You should also open the hood and leave the driver’s door open with a “DO NOT CLOSE” sign on the door. Why? If someone closes the driver’s door, opening it again with the 12v auxiliary battery connected will cause the hydraulic system to pressurize. Disconnecting the auxiliary battery prevents the hydraulic brake pump from inadvertently pressurizing the brake system and pushing the pistons out of the caliper with either the brake pads out or your fingers in the way.
- To allow the brake fluid to return to the master cylinder reservoir when pushing the pistons back into the calipers, remove the two blue ABS relays located in the engine compartment fuse box. NOTE: Toyota doesn’t recommend clamping the brake hose and venting the caliper at the bleeder fitting during piston retraction.
- It’s always a good idea to move the smart key to another room so that the vehicle can’t be turned on with something in the brake system disconnected or disabled. It helps to avoid setting numerous brake system codes and the dash warning indicators lighting up like a Christmas tree.
- You can replace brake pads without a scan tool, but if you replace any hydraulic components, a Toyota Techstream or equivalent scan tool must be used to bleed the brake system. If you don’t, bleeding will be incomplete, which could cause the ABS light to come on, or even worse, result in an accident.
You should also open the hood and leave the driver’s door open with a “DO NOT CLOSE” sign on the door. Why? If someone closes the driver’s door, opening it again with the 12v auxiliary battery connected will cause the hydraulic system to pressurize.
Honda Accord Hybrid
Tips for Updating Control Units
- High temperature in the engine compartment might cause the motor control module (built into the PCU) to become too hot to run the update. If the engine has been running before this procedure, open the hood and cool the engine compartment down. Use a fan to reduce wait time or grab another vehicle to work on while you’re waiting.
- When updating control units, check OEM service information first. To find detailed procedures and safety precautions, refer to Honda’s website, ALLDATA Repair or ALLDATA Collision.
Collision Shut-off History Clear Command
When the battery condition monitor module receives a collision detection signal (CDS) from the SRS unit, the battery condition monitor module updates the collision shutoff history and stores it in the nonvolatile memory located in the module. The battery condition monitor module stops supplying power to the high-voltage circuits disrupting the control signal to be sent to the high-voltage contactor inside the battery module the next time the system is turned on. To resume the power supply to the high-voltage circuits, the collision shutoff history needs to be cleared. Do the following procedures to clear the collision shutoff history.
- Inspect the battery module for exterior damage or leaks. If no damage is found, go to step 2.
- Check the battery high voltage wires (orange coated) for damage. If any damage is found, replace the damaged wire harness or component, then go to step 3.
- Connect the HDS or equivalent scan tool.
- Select the Electric Powertrain system.
- Clear the DTC.
Bonus Collision Tip
High temperatures may damage the battery module. When drying paint in a heated paint booth, make sure the temperature does not exceed 149 °F (65 °C).
Ford Fusion Hybrid
Power Disconnect Safety
- Never install the service disconnect plug when a high-voltage service cover is removed. Always install the cover prior to connecting the service disconnect plug. The cover prevents inadvertent contact with the high voltage which is present at several points under the cover. Failure to follow these instructions may result in serious personal injury or death.
- Always disconnect the 12-volt battery before servicing the direct current to alternating current inverter or alternating current powerpoint to prevent the risk of high voltage shock. Failure to follow this instruction may result in serious personal injury.
Be Safe! Look for more hybrid and electric vehicle tips from ALLDATA in the coming months.