Precautionary measures
When working on the electrical system, be sure to observe the following precautions:
- A) Be extremely careful when servicing the electrical components of the engine. They can easily be damaged if they are not properly tested, connected incorrectly or handled carelessly.
- b) Never leave the ignition on for a long time with the engine off.
- V) Never disconnect the wires from the battery while the engine is running.
- G) Observe the correct polarity when connecting the wires from the battery of another vehicle when performing a jump start, see paragraph «Starting the engine from a foreign battery» at the beginning of this guide.
- d) Before working on the electrical system, be sure to disconnect the ground wire from the battery, but first read the battery disconnect procedure below.
Before performing any procedure included in this chapter, it is recommended that you review the information related to safety when working on engine electrical systems. This information is given in the paragraph «Safety first!» at the beginning of this guide.
Disconnecting the battery
Some systems, such as the anti-theft alarm system, audio system, power door locks, or power windows, require continuous battery power. This is necessary either to ensure their continuous operation, or to save the contents of the memory of the control units, for example, the powertrain control module (RSM), which will be lost if the battery is disconnected. Therefore, every time you need to disconnect the battery, consider the following points first so that you are not surprised by the consequences of this action:
- a) The PCM module of the engine management system, when the battery is disconnected, loses some of the data stored in its memory. These are engine operating parameters, including idle, logged DTCs, and system monitoring functions required to test the emission control system. Each time the battery is disconnected, it may take a certain amount of time for the computer to collect engine data.
- b) On all cars with power locks, it is recommended to remove the key from the ignition and keep it with you so that it does not end up locked inside the car after accidentally locking the door locks when connecting the battery!
To avoid some of the aforementioned problems, you can use uninterruptible power supplies, known by names such as «memory storage devices» or «input code storage devices». How to use them varies depending on the type of device you are using. As a rule, such a device is connected to the cigarette lighter socket and is connected by its own wiring to a backup power source. The vehicle's battery is then disconnected from the electrical system and the memory saver supplies enough current to store the audio unit's input code and other information in the PCM's memory. In doing so, it allows electrical circuits that are constantly energized, such as the clock and audio system memory, to operate, providing isolation from the battery when a short circuit occurs while servicing the vehicle.
Attention! Some of these devices allow a significant amount of current to flow, which can result in the continued operation of many vehicle systems even when the standard battery is disconnected. If a memory saver is being used, make sure that the problematic circuit is de-energized before doing any work!
Attention! If you are working near an airbag, disconnect the battery and do not use the memory saver. If using this device to maintain power while working near an airbag, be aware that the airbag may be accidentally activated, causing it to deploy.
The battery on all models is located in the left front corner of the engine compartment. To disconnect the battery for service procedures that require the vehicle's on-board power to be turned off, loosen the nut by «negative» battery terminal and disconnect the ground wire from the battery. Insulate the end of the wire to prevent accidental contact with the battery terminal.
Initializing systems after disconnecting/connecting or replacing the battery, or after recharging a depleted battery
All models
After disconnecting/connecting or replacing the battery or recharging a depleted battery, you may experience a malfunction or total inoperability of the sunroof motor. Also, the anti-pinch function will not work properly. If this occurs, the sunroof initialization procedure described below should be followed. Push the corresponding switch towards the TILT switch (incline) (Lexus) or TILT UP (tilt up) (Toyota) and keep it. The sunroof will tilt up and down, then slide to the open position and close. After moving the sunroof to the closed position, release the switch. Check that the sunroof is working properly. If it does not work properly, contact the dealer's technical service department.
Lexus models
Adaptive Front Lighting System
After disconnecting/connecting or replacing the battery or recharging a depleted battery, the adaptive front lighting system may not work properly or be completely inoperative. To perform system initialization:
- 1) Start the engine. Adaptive front lighting off indicator (AFS) will start flashing.
- 2) Turn the steering wheel all the way to the left or right, then press the AFS switch twice.
- 3) Turn the steering wheel all the way to the opposite side, and then press the AFS switch twice.
- 4) Return the steering wheel to the center position (straight ahead), then double-click the AFS switch. The AFS off indicator will turn off.
If the AFS off indicator continues to flash, repeat the above procedure.
Power Door System
After disconnecting/connecting or replacing the battery or recharging a discharged battery, the power tailgate system may malfunction or become completely inoperative. To initialize this system, simply close the tailgate completely with your hand. If it still does not work properly after this, have the system checked by a Lexus dealer or other qualified person.
Power windows
After disconnecting/connecting or replacing the battery or recharging a depleted battery, the power window system may not work properly or be completely inoperative. In addition, the anti-pinch function will not work properly. At the same time, the indicators in the power window switches will flash. To perform initialization of this system:
- 1) Press the power window switch on each door and lower the windows half way.
- 2) Pull the corresponding switch up until the window closes and hold it for a second. Make sure windows open and close automatically now. If the power windows do not work, have the system checked by a Lexus dealer or other qualified person.