Hyundai and Honda hybrid safety tips
Mar. 02 2021
Mar. 02 2021

As an experienced tech, you know hybrid and electric vehicles can be dangerous to work on. The question is “how do you safely and efficiently service and repair them? Here are a few manufacturer-specific tips that will help you just that.

Hyundai IONIQ Plug-in Hybrid

High Voltage Shut-off Procedures

Occasionally we need to shut down a hybrid vehicle’s high-voltage system to service or repair certain components in that system. But before you begin, always review then precisely follow the specific procedures supplied by the vehicle’s manufacture. Each step is vital to your safety and shouldn’t be skipped.

Manufacturer’s WARNING: Be sure to read and follow the "High Voltage Shut-off Procedures" before doing any work related with the high voltage system. Failure to follow the safety instructions may result in serious electrical injuries.

Please use caution and follow the high voltage shut-off procedure when working on or around the following high voltage components:

  • High Voltage Battery Pack Assembly
  • Power Relay Assembly (PRA)
  • BMS ECU/li>
  • Hybrid Power Control Unit (HPCU)
  • Hybrid Drive Motor
  • HSG
  • Electric A/C Compressor
  • Low DC/DC Converter (LDC)
  • Power Cable
  • Electric Compressor


High Voltage Shut-off Procedure


1. Turn the ignition switch OFF.
2. Remove the luggage board (A).

Battery Luggage Board

3. Remove the 12V battery cover (A) and then disconnect the auxiliary 12V battery negative (-) terminal.

4. Remove the safety plug cover (A).

Safety Plug Cover
Hyundai Safety Plug

5. Unfasten the hook (A) and then remove the safety plug (C) by pulling the lever (B) to the direction of arrow.


6. Wait for more than 5 minutes so that the capacitor in the high voltage system can be fully discharged.
7. Measure the voltage between the inverter terminals to check that the capacitor in the inverter is discharged completely.

  • Remove air cleaner assembly and air duct.
  • Disconnect the inverter power cable (A).
  • Disconnect the inverter power cable as shown in the image below.

Hyundai Inverter Power Cable
Disconnecting Hyundai Inverter Cable
  • Measure the voltage between the inverter (+) terminal and the inverter (-) terminal.
Hyundai Inverter Test


Inverter Test Results


  • Less than 30V – High voltage circuit properly shut off
  • More than 30V – Fault on high voltage circuit


NOTE: If you measured more than 30V, check if the safety plug is removed completely. If you measured more than 30V despite the safety plug is removed, there can be serious problems on the high voltage circuit. In this case, check for diagnostic trouble codes and never touch the high voltage system circuits.

Bonus Hyundai IONIQ Service Tip

Procedure for Entering Engine Forced Activation Mode

If the engine needs to be running constantly while the vehicle is stopped to inspect the emission system or perform maintenance on the vehicle, you can safely do that by putting the vehicle in engine forced activation mode. Here’s how you do it.

NOTE: The procedure for engine forced activation mode must be completed within 60 seconds. In case the procedure is not completed within the specified time, the process is reset, and you must start again from step (1).

IMPORTANT: Before you start, place the shift lever in P range while the vehicle is stopped. Engage the parking brake.

  1. Do NOT press on the brake pedal and press the Engine Start/Stop button 2 times to enter IG ON mode.
  2. Place the shift lever in P range and then press the accel pedal 2 times.
  3. Place the shift lever in N range and then press the accel pedal 2 times.
  4. Place the shift lever in P range and then press the accel pedal 2 times.
  5. Press on the brake pedal and press the Engine Start/Stop button to start the engine and maintain idling.

CAUTION: The engine will continue to remain idling and engine forced activation mode is maintained even if the gear is shifted to different range.

  • The "READY" lamp will blink in the cluster when the vehicle is in engine forced activation mode. Be sure to check that the "READY" lamp is blinking to ensure that engine forced activation mode is entered correctly.
  • The "READY" lamp will continue to blink until engine forced activation mode is cancelled. To cancel engine forced activation mode, press the Engine Start/Stop button and switching to IG OFF mode. The "READY" lamp will stop blinking when the forced activation mode is successfully cancelled.

Blast from the past

Stop Current Flow Through High Voltage Cables on a 2000 - 2006 Honda Insight

The Honda Insight was the first mass-produced hybrid automobile sold in the US. It became available in 2000 but was discontinued after 2006 model year due to lackluster sales. Honda brought back a new, redesigned Insight in 2019.

If you happen to get a 2000 to 2006 Insight in your shop, here is the simple steps to turn on and off power to the high voltage electrical circuit.

Manufacturer’s WARNING: Follow this procedure before you work on or near any high voltage components. Follow it exactly, otherwise, you may injure yourself or damage equipment.

1. Turn the ignition switch OFF.
2. Remove the cargo floor mat.

3. Remove the battery module cover (A) from the IPU lid and remove the locking cover (B) from the battery module switch.

Honda Insight Battery Module Cover
Honda Insight Switch



4. Turn the switch (A) OFF, then turn the locking cover around (B) and put it back on the switch.
5. Wait for at least five minutes to let the condensers discharge.

6. Remove the under-cover (2 screws, 4 clips).

removing undercover screws
Removing the IPU lid

7. Remove the IPU lid.

8. Measure voltage at the junction board terminals.

Measure Voltage at Junction Teminals


There should be 10.0V or less. If voltage is present, there is a problem in the circuit; do the diagnostic trouble code troubleshooting first.

Be Safe! Look for more hybrid and electric vehicle tips from ALLDATA in the coming months.

Want to see how ALLDATA can improve shop efficiency? Check out our suite of products, each designed to contribute to both shop efficiency and productivity.

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