Alternator 27060-38040 27060-38070 104210-6130 104210-6131

I. Pre-Installation Preparation (Safety & Compatibility First)

Safety Preparatory Operations

• Disconnect the negative battery cable. For Lexus hybrid models, additionally shut down the high-voltage system power supply, follow the instrument prompts to complete the high-voltage power-off procedure, and wait 5-10 minutes to discharge residual voltage.

• For vehicles equipped with intelligent driving assistance systems (e.g., Lexus Safety System+), it is recommended to first read and record fault codes using a diagnostic tool to prevent data loss from electronic modules during installation.

Tool & Component Verification

• Essential tools: Socket wrench (primarily 10/12/14mm), torque wrench (accuracy ±1N・m), special belt tensioner tool (some models require Lexus genuine SST tool), pry bar, and wire organizers.

• Confirm the new generator’s model compatibility: Lexus generator part numbers typically start with "27060-" (e.g., 27060-0V020 for ES 200). Verify that the power (mostly 100-150A), mounting holes, and number of terminals match the original vehicle. Inspect the new generator: ensure the brush length is ≥5mm, the bearing operates without jamming, the rotor rotates smoothly, and remove oxide layers from the terminal posts.

II. Core Installation Steps (Universal Process + Model-Specific Key Points)

1. Securing the Generator Body (Precise Torque Control)

• Universal operation: Fit the generator onto the engine compartment mounting bracket, align the mounting holes, manually thread the bolts (without full tightening), and adjust the body position to ensure the pulley is coplanar with other idler pulleys (deviation ≤0.5mm).
• Model-Specific Torque Specifications:| Model | Fixing Method | Torque Specification ||-------|---------------|----------------------|| Lexus ES (2018-2023) | 2 fixing bolts | Main bolt: 39N・m; Auxiliary bolt: 25N・m || Lexus RX (4th Generation) | 1 bolt + 1 locating pin + 1 nut | Bolt: 43N・m; Nut: 19N・m || Lexus NX (2022+) | 3 symmetric bolts | All 35N・m (tighten in stages for aluminum alloy brackets) || Lexus LS (Flagship Model) | Mounting bracket with shock pad | 32N・m (avoid over-tightening to prevent shock pad damage) |

2. Installing the Drive Belt (Belt Tensioner Operation Key Points)

• Universal principle: Install the belt according to the belt routing diagram in the engine compartment (usually affixed to the inside of the hood or intake manifold on Lexus models). Ensure the belt is fully seated in all pulley grooves without misalignment.
• Model-Specific Operations:

• Equipped with 2.5L naturally aspirated engine (e.g., ES 250): Rotate the belt tensioner clockwise (right-hand thread), mount the belt, then slowly release the tensioner. Press the middle of the belt—normal deflection is 5-8mm (stricter than Toyota models).

• Equipped with 2.0T turbocharged engine (e.g., NX 350): Use a special tool to secure the tensioner piston to avoid hydraulic mechanism failure during installation. Wait 30 seconds after belt installation to allow the tensioner to reset automatically before checking tension.

• Hybrid models (e.g., RX 450h): The generator belt shares the tensioning system with the motor drive belt. Ensure consistent tension for both belts during installation to avoid uneven one-sided stress.

3. Connecting the Wiring (Premium Model Electronic Protection Key Points)

• Universal steps:

1. First insert the generator’s multi-pin connector (mostly 4/5-pin waterproof connector on Lexus), confirm full engagement by hearing a "click," and fit the waterproof and dustproof sleeve.

2. Connect the cable to the generator’s B terminal (thick terminal post), tighten the nut to 12N·m with a torque wrench (slightly higher than Toyota models to avoid poor contact under high current), and install the genuine insulating protection cap.

• Model-Specific Notes:

• Models with start-stop function (e.g., ES 300h): Additionally connect the "start-stop control signal wire" (thin pin terminal). Ensure the connector is secure to prevent start-stop function failure.

• Flagship LS model: A temperature sensor is installed at the B terminal. Avoid squeezing the sensor probe during wiring (sensor failure will trigger a charging system alarm).

4. Post-Installation Inspection (Electronic System Verification)

• Wire organization: Secure cables with genuine-spec wire clips, keeping them away from high-temperature areas such as the exhaust pipe and turbocharger (distance ≥5cm). For hybrid models, separately fix high-voltage system-related wiring to avoid entanglement with 12V wiring.
• Functional Verification:

1. Reconnect the negative battery terminal, turn on the ignition (without starting the engine), and observe the instrument’s "charging indicator light"—it should briefly illuminate and then turn off (normal self-check).

2. Start the engine, let it idle for 3 minutes, listen for abnormal noises from the generator (a "buzzing" sound indicates bearing wear), and ensure no charging system fault light appears on the instrument.

3. Use a multimeter to test the output voltage: 13.8-14.2V at idle (Lexus has higher voltage control precision; inspect the regulator if outside this range). The voltage should not drop below 13.5V when loads such as air conditioning and headlights are activated.

• Advanced Verification (Premium Configuration Models):

• For vehicles with high-power electronic devices (e.g., navigation, Mark Levinson audio), test device operation stability after startup to ensure no lag caused by voltage fluctuations.

• For hybrid models, use a diagnostic tool to read the "generator charging status" (normal display: "90%-130A") and confirm the high-voltage system and 12V system work synergistically.

III. Lexus-Exclusive Precautions

1. Special Requirements for Hybrid Models: For models such as RX 450h and LS 500h, the 12V generator is integrated into the hybrid transaxle. Remove the hybrid system guard before disassembly/installation. Do not touch high-voltage interfaces (orange-marked) with metal tools. Perform a "hybrid system reset" using a diagnostic tool after installation.

2. Heat Dissipation Protection for Turbocharged Models: For models such as NX 350 and IS 350, the generator is located near the turbocharger’s exhaust side. Check the integrity of the heat shield during installation and secure wiring outside the shield to avoid high-temperature aging.

3. Bolt Reuse Taboo: Lexus generator fixing bolts are mostly high-strength rustproof bolts. Replace with genuine new bolts if thread damage or deformation occurs after disassembly (do not use ordinary bolts as substitutes), otherwise generator body vibration may occur.

4. Fault Light Handling: If the charging system fault light illuminates after installation, first check wiring connections (especially the B terminal and multi-pin connector). Then use a diagnostic tool to read codes such as "generator output abnormality" or "regulator communication failure" for targeted troubleshooting.

References：

Key Points from Lexus Original Maintenance Manuals

Supplementary Practical Experience from Owner Communities and Forums