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Type :
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AIternator
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Specification :
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28V 35A
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Pulley :
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Brand :
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nuojin
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Number :
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4BE1 8944723300
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Quality :
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Renovate
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Delivery time :
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10DAY
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Special tools: Socket wrench (10-19mm), torque wrench, Phillips screwdriver, crowbar, belt tension gauge
Supporting accessories: Generator fixing bolts (original factory specifications), grounding wire, wire terminals, insulating tape, thread locking adhesive
Auxiliary materials: Engine oil (for lubricating bearings), cleaning agent (for removing oil stains on mounting surfaces)
Disconnect the vehicle's main power supply (remove the negative battery cable) to prevent short circuits and burning of electrical components during installation.
Inspect the condition of the new generator: The rotor should rotate smoothly without jamming or abnormal noise; the wiring terminals should be free of oxidation and corrosion; the pulley should have no deformation or cracks.
Clean the oil stains, rust and impurities on the surface of the generator mounting bracket to ensure tight fit.
Lift the generator to the mounting bracket on the engine side, and align the generator lugs with the mounting holes of the bracket.
Insert the main fixing bolts (long bolts) and locating pin bolts (short bolts), manually screw in the nuts until they are preliminarily fixed, do not tighten them completely to reserve space for adjusting belt tension.
According to the engine belt routing diagram, fit the drive belt onto the generator pulley, crankshaft pulley and tensioner pulley.
Pry the generator body (a crowbar can be used to push against the stress point on the side of the generator housing) to adjust the distance between the generator and the crankshaft until the belt tension meets the requirements.
Belt tension standard for 28V 35A generator: When a force of 10kgf is applied to press the midpoint of the belt, the deflection should be 8-12mm; alternatively, use a belt tension gauge for measurement, with the tension value referring to 150-200N (subject to the vehicle maintenance manual).
After the tension is properly adjusted, tighten the fixing bolts with a torque wrench. The recommended torque value is 25-30N·m (varies slightly with different vehicle models). Apply thread locking adhesive to the bolts to prevent loosening.
Core Principle: The 28V system is a high-voltage DC circuit. The positive and negative poles must be correctly identified during wiring, and reverse connection is strictly prohibited.
Positive pole wiring: Connect the generator output terminal (marked as B+ or BAT) to the positive battery cable, crimp it firmly with the matching terminal, install an insulating sheath, and tighten the bolt to a torque of 10-15N·m.
Excitation circuit connection:
Separately excited type: Connect the excitation wire from the regulator to the generator (marked as F or FIELD), and connect it to the excitation control terminal of the vehicle wiring harness.
Self-excited type: No additional excitation wire is required; it only needs to ensure that excitation is automatically established when the B+ terminal is powered on.
Distinguish between self-excited and separately excited generators:
Grounding wire connection: Connect the grounding terminal on the generator housing (marked as G or EARTH) to the engine block reliably. The cross-sectional area of the grounding wire should not be less than 4mm² to ensure the grounding resistance is less than 0.1Ω.
Other control wires: If the generator is equipped with a charging indicator control wire (marked as L), it should be connected to the instrument panel charging indicator circuit for monitoring the power generation status.
Check that all bolts are tightened, the circuit connections are firm, and there is no risk of loosening or short circuit.
Rotate the generator pulley to confirm that there is no jamming or abnormal noise, and the belt does not deviate or slip.
Reconnect the negative battery cable and switch on the main power supply.
Start the engine and run it at idle speed (approximately 750r/min). Use a multimeter to measure the generator output voltage:
The voltage at idle speed should be 28.0-28.5V;
When the engine speed rises to the rated speed (approximately 2500r/min), the voltage should stabilize at 28.5-29.0V, and the current output can reach 35A (under full load).
Observe the instrument panel charging indicator: The indicator should turn off after startup. If it stays on, it indicates a fault in the circuit or excitation system.
Full-load test: Turn on all electrical equipment of the vehicle (lights, air conditioning, heater, etc.) and run for 10-15 minutes. The temperature of the generator housing should not rise abnormally (≤80℃), and there should be no peculiar smell or abnormal noise.
Disconnect the negative battery cable throughout the entire installation process to prevent short circuits that could burn out the generator rectifier bridge, voltage regulator, or vehicle ECU. It is strictly forbidden to plug or unplug the generator wiring terminals when the power is on.
The 28V high-voltage DC system is sensitive to polarity. The B+ terminal must be connected to the positive pole of the battery, and the grounding terminal must be connected to the engine block or vehicle body ground. Reverse connection will instantly burn out the internal diodes and regulator, which is irreparable.
The cross-sectional area of the generator output wire (from B+ to the battery) shall not be less than 16mm² to avoid wire heating, aging, and even fire under high current (35A) conditions.
The excitation wire and indicator control wire shall use automotive-specific wiring harnesses with a temperature resistance of ≥105℃. Terminals shall be crimped at the joints and tightly wrapped with insulating tape.
The traditional "grounding spark test" method will damage the internal electronic components of the generator. To check the power generation status, measure the voltage with a multimeter or judge by the charging indicator on the instrument panel.
Insufficient tension: The belt will slip, resulting in reduced power generation efficiency, accelerated wear of the belt and pulley, and abnormal noise.
Excessive tension: It will aggravate the wear of the generator bearing, shorten the service life, and even cause belt breakage.
Standard value: When a force of 10kgf is applied to press the midpoint of the belt, the deflection shall be 8-12mm; or the tension gauge reading shall be 150-200N (subject to the vehicle manual).
Clean the contact surfaces between the generator lugs and the mounting bracket with a cleaning agent to remove oil stains, rust, and sediment, ensuring no gaps after installation and avoiding resonance noise during operation.
The generator pulley must be aligned with the crankshaft pulley and tensioner pulley on the same plane, with a deviation of no more than 1mm. Otherwise, it will cause belt edge wear and detachment.
References：
ISUZU Diesel Engine Maintenance Manual (Original Factory Technical Documentation): This is a commonly used industry term referring to the official maintenance manual issued by ISUZU for specific vehicle models/engines. It contains specifications for generator installation, torque application, electrical wiring, etc. The corresponding version should be obtained through the ISUZU after-sales system or authorized channels by providing your vehicle’s VIN/engine model.
GB/T 23641-2009 Technical Specifications for Automotive Generators: Upon verification, this standard number actually corresponds to "Fiber-reinforced Unsaturated Polyester Molding Compounds (SMC/BMC) for Electrical Purposes". It was replaced by GB/T 23641-2018 on January 1, 2019, and is irrelevant to automotive generators, which is a clerical error. The common national standards applicable to automotive generators include GB/T 13539 (Low-voltage Electrical Appliances) and QC/T 423 (Automotive Alternators), which can be used to verify indicators such as voltage, insulation, and temperature rise.
Requirements such as power-off operation, precise alignment, belt tension control, torque application, wiring polarity compliance, and test parameters are universal specifications and industry best practices for automotive generator installation. They are compiled based on the 28V 35A power rating and the typical operating conditions of ISUZU commercial vehicles/engineering vehicles, with reference to maintenance manuals and after-sales training materials of similar vehicle models.
The values in the tables (e.g., torque, tension, voltage ranges) are typical reference values for on-site quick consultation. The official maintenance manual for your specific vehicle/engine must be used as the final authority to avoid faults caused by model differences.
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