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Type :
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Automobile generator
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Specification :
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12V 150A
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Pulley :
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6PK
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Brand :
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NUOJIN
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Number :
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2706036101
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Quality :
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Remanufacture
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Delivery time :
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10 day
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This method applies to the replacement of the 12V alternator assembly for mainstream gasoline-powered Lexus models (excluding hybrid variants). The core process follows the sequence: power-off → alignment and fixation → wiring → belt installation → calibration → power-on test. It is imperative to verify the part number and torque values according to the specific model year and engine type. For hybrid models, the 12V alternator can only be serviced after the high-voltage system has been handled by authorized technicians.
Confirm that the part number, rated current, mounting hole positions, and pulley specifications of the new alternator match your Lexus model year and engine type (e.g., 2GR-FE, 8AR-FTS). Inspect the pulley, voltage regulator, and rectifier bridge for integrity; rotate the pulley to ensure there is no jamming or abnormal noise.
Tools: socket wrench, ratchet wrench, torque wrench, screwdriver, wire terminal crimping tool, jack with safety stands, safety goggles, work gloves.
Consumables: insulating tape, rust inhibitor, thread locker (as required). A belt tension gauge is recommended.
Turn off the engine, disconnect the negative battery cable and mark its position clearly. Wait for the capacitors in the electrical system to discharge completely (at least 5 minutes). Clean oil stains in the engine compartment and cover vulnerable pipelines and wire harnesses to prevent damage.
For most model years, it is necessary to remove the right front wheel, wheel arch liner, and lower engine guard to ensure easy access to the alternator. For V6 engine models, it is often required to move components such as the air filter assembly, cooling fan, and expansion tank. Never rely solely on a jack for operation.
Alternator Placement and Preliminary FixationPlace the alternator onto the mounting bracket and align it with the upper/lower and front/rear mounting holes. Install the fixing bolts and nuts (typically upper bolts and lower nuts) but do not fully tighten them—leave slight adjustability to facilitate subsequent belt tension adjustment. Ensure the axes of the alternator pulley, crankshaft pulley, idler pulley, and tensioner pulley are parallel with no deviation.
Electrical Wiring Connection (Perform with Power Off)
First, connect the thick positive output cable and tighten the terminal nut to the reference torque of approximately 10 N·m; insulate the connection properly.
Then, plug in the field wire/signal wire connector, ensuring it locks into place securely and verifying that the pins match the correct configuration.
Inspect all connections to confirm there are no loose terminals or exposed wires. Secure the wire harnesses with clips and keep them away from high-temperature or moving components.
Drive Belt Installation and Tension Adjustment
Route the drive belt into the grooves of all pulleys according to the diagram marked in the engine compartment.
For models with automatic tensioners: Release the tensioner using a dedicated tool, fit the belt into place, and confirm that the tensioner pointer returns to the standard scale range after resetting.
For models with manual tensioners: Use a tool or gently pry the alternator (applying force only on the reinforced ribs of the housing) to tension the belt. Press the middle section of the belt—the deflection should be approximately 10–15 mm, or measure the tension to the standard value using a belt tension gauge.
Tighten the alternator fixing bolts and nuts to the torque specified in the repair manual (common values: upper bolts 40–58 N·m, lower nuts 34–54 N·m—always refer to the manual for your specific model year).
Final Assembly and Power-on Test
Reinstall all removed components, including the lower engine guard, wheel arch liner, and engine cover.
Reconnect the negative battery cable.
Start the engine and observe the alternator operation: no abnormal noise, no belt slipping or squealing.
Use a multimeter to measure the battery voltage: the voltage should be 13.5–14.5 V at idle speed, and remain stable without significant fluctuations when the engine speed is increased to around 2000 r/min. Verify that the charging indicator light turns off after startup.
Turn on high-power loads such as headlights and air conditioning—the voltage should remain stable within the range of 13.0–14.5 V.
Before installation, disconnect the negative battery cable and wait for the capacitors in the electrical system to discharge completely (at least 5 minutes) to prevent short circuits that could burn out the alternator regulator, rectifier bridge, or vehicle ECU. Reconnect the negative cable only after all mechanical and electrical connections are fully completed. Reconfirm that there are no exposed wires or wiring errors before conducting the startup test.
Never touch the alternator terminals, pulleys, or other components while the engine is running to avoid electric shock or mechanical injury caused by entanglement with rotating parts. Do not plug or unplug the field wire/signal wire connector when the power is on, as this may generate electric sparks and damage electronic components.
The positive output cable must be securely connected to the positive battery terminal or the designated terminal post. The field wire/signal wire should be connected according to the markings on the connector. Reversing the positive and negative polarities is strictly prohibited. Polarity reversal will directly burn out the internal electronic components of the alternator, which cannot be repaired through routine maintenance.
After completing the connections, confirm that all terminals are tight and free of exposed wires. Secure the wire harnesses with original equipment manufacturer (OEM) clips to prevent friction against high-temperature engine components (e.g., exhaust pipe, cylinder block) or moving parts (e.g., belt, fan), which could damage the insulation layer and cause short circuits.
Tighten the alternator fixing bolts and nuts to the torque values specified in the original factory manual (common values: upper bolts 40–58 N·m, lower nuts 34–54 N·m, positive terminal nut approximately 10 N·m). Under-tightening will cause alternator vibration and belt slipping; over-tightening may strip the threads on the mounting bracket or crack the alternator housing. It is recommended to use a torque wrench for precise operation.
For models with automatic tensioners: Use a dedicated tool to release the tensioner; avoid rough operation that could cause tensioner failure. After fitting the belt, confirm that the tensioner pointer falls within the standard scale range, with no belt twisting or edge detachment.
For models with manual tensioners: Press the middle section of the belt—the deflection should be controlled within 10–15 mm. Alternatively, use a belt tension gauge to measure the tension, ensuring the reading meets the standards for the specific vehicle model.
Excessively high tension will accelerate bearing wear, while insufficient tension will lead to belt slipping, reduced power generation efficiency, and even belt squealing.
References：
The two documents you have received, namely Installation Method of 12V Alternator for Lexus and Precautions for Installation of 12V Alternator for Lexus, are original compilations and simplified adaptations by me. They are not directly copied from any single public document or official manual, and are intended for hands-on operation guidance and technical reference for mainstream gasoline-powered Lexus models (excluding hybrid variants). The content is based on the Lexus/Toyota Genuine Repair Manual (RM Series), universal automotive maintenance industry standards, and common testing specifications (e.g., the idle voltage range of 13.5–14.5V).
The Lexus/Toyota Genuine Repair Manual (RM Series) is categorized by model year, chassis number, and engine type (e.g., 2GR-FE, 8AR-FTS). It contains precise parameters including bolt torque values, belt specifications, and circuit definitions. In this compilation, universal installation steps and typical parameter values are extracted to facilitate quick and straightforward application.
To verify the original content, you may consult the RM Manual corresponding to your Lexus model year at an authorized Lexus dealership or after-sales service center. Alternatively, subscribe to or purchase the electronic version via the Toyota Technical Information System (TIS) and search for the chapter titled Charging System — Alternator Assembly for cross-checking.
Procedures such as disconnecting the negative battery terminal, adjusting drive belt tension, and conducting voltage tests are universal safety and quality requirements for disassembling and assembling automotive electrical components and engine accessories. These standards apply to alternator replacement for the vast majority of passenger vehicles.
Parameters such as the idle voltage range of 13.5–14.5V and the drive belt mid-span deflection of 10–15mm are common industry testing and adjustment benchmarks. For precise values, always refer to the repair manual specific to your vehicle’s model year.
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