Mitsubishi 12V Generator Installation Method (Technical Standard Version)

I. Pre-installation Preparation

1. Vehicle Power-off

2. Component Inspection

• Verify that the generator model and voltage rating (12V) meet the vehicle’s original factory requirements. Check that the generator housing is free of cracks and the bearings show no signs of looseness or abnormal noise.

• Inspect accessory parts: Ensure the pulley, fastening bolts, adjustment arm, and generator wiring harness connectors are intact with no damage to the insulation layer.

• Clean the contact surfaces of the generator mounting bracket and engine block to remove rust and oil stains, ensuring a tight fit.

II. Installation Steps

1. Positioning and Securing the Generator Unit

• Place the generator in the designated position on the engine mounting bracket and align the mounting holes.

• Install the fastening bolts (including support bolts), distinguishing between fixed-end bolts and adjustment-end bolts. Do not fully tighten them initially to reserve space for adjusting belt tension.

• Tighten the fixed-end bolts in accordance with original factory torque specifications (typically 25–35 N·m; refer to the vehicle maintenance manual for exact values). Avoid under-tightening, which can cause vibration and noise, or over-tightening, which may damage bracket threads.

2. Drive Belt Installation

• Route the drive belt around the generator pulley, crankshaft pulley, and idler/tensioner pulley (if equipped) strictly following the engine belt routing diagram.

• Adjust the generator adjustment arm to set proper belt tension: Press the middle of the belt with hand; the deflection should be 10–15 mm (approximately one finger gap), with slight variations for different vehicle models.

• Tighten the adjustment-end fixing bolts and recheck the belt tension to ensure no slipping risk.

3. Electrical Wiring Connection

• Field wire (small harness): Connect the field terminal (usually marked F/D+) on the rear of the generator to the corresponding vehicle wiring harness plug. Secure the connector with a clip after fully inserting it to prevent loosening.

• Output wire (main power cable): Connect the positive output terminal (marked B+/+) of the generator to the battery positive cable or starter power terminal. Tighten it with the supplied lock washer nut to a torque of 18–25 N·m (reference value). Apply a small amount of conductive grease to the connection to prevent oxidation.

• Ground wire: Ensure the generator housing is reliably grounded to the engine block. If grounding is insufficient, install an additional grounding wire.

• Route all wiring harness connectors away from high-temperature engine areas and moving parts to avoid abrasion and short circuits.

III. Post-installation Commissioning and Inspection

1. Power Restoration

2. Startup Test

• Start the engine and observe the generator operation at idle speed: Ensure there is no abnormal noise and the belt does not slip or squeal.

• Use a multimeter to measure the generator output voltage. At idle, the voltage should be 13.5–14.5 V; it should remain within this range when the engine speed rises to 2000 r/min, indicating normal power generation.

3. Load Test

4. Final Fastening Recheck

Precautions for Installation of Mitsubishi 12V Generator (Original Factory Specification Version)

Mandatory Requirement for Power-off Operation

Component Compatibility Verification

• Confirm that the generator model, mounting hole positions, and pulley specifications are consistent with the vehicle’s original factory standards. Generator brackets vary across engines of different displacements and must not be interchanged.

• For new generators, inspect the oil seal and bearing conditions to ensure there is no oil leakage, looseness, or abnormal noise. Before reinstalling a used generator, clean the heat dissipation air ducts to remove oil stains and dust blockages.

Bolt Fastening and Torque Control

• Tighten the fixed-end bolts and adjustment-end bolts step by step in accordance with original factory torque specifications (conventional fixed bolts: 25–35 N·m; B+ terminal nut: 18–25 N·m). The use of pneumatic impact wrenches for forced tightening is strictly prohibited to prevent thread slipping or bracket deformation.

• Follow the diagonal uniform tightening principle for bolt installation sequence to avoid cracks on the generator housing caused by uneven stress.

Drive Belt Installation Prohibitions

• The belt routing path must strictly comply with the diagram on the engine compartment sticker. Incorrect routing or omission of the tensioner/idler pulley will cause belt slipping and abnormal generator speed.

• Control the belt tension to a deflection of 10–15 mm (press the middle section of the belt with a force of approximately 10 kgf). Excessively loose belts are prone to slipping and overheating, while over-tightened belts will accelerate wear on the generator bearing and water pump bearing.

• Do not use a crowbar to pry the generator housing for belt tension adjustment; use the adjustment arm for standard regulation.

Electrical Wiring Connection Specifications

• Strictly match the terminal markings: B+/+ connects to the main power cable, and F/D+ connects to the field wire. Reversed connections will burn out the voltage regulator.

• Install a lock washer at the main power cable connector. After tightening, wrap the connection with insulating tape for protection. Secure the field wire connector with a clip to prevent detachment due to engine vibration.

• Ensure the generator housing is reliably grounded to the engine block. Poor grounding will cause unstable charging voltage and intermittent malfunctions of electrical equipment.

• Route all wiring harnesses away from high-temperature and moving components such as the exhaust pipe and timing belt. Install rubber sleeves at contact points between the harnesses and the engine block to prevent abrasion.

Safety Guidelines for Operation Testing

• After starting the engine, first observe the belt operation status. Conduct voltage testing only when there is no belt misalignment or squealing noise. Continuous testing during abnormal generator operation is prohibited.

• Never disconnect the battery cables or plug/unplug wiring harness connectors while the generator is in operation; the instantaneous high voltage will damage internal electronic components.

• For load testing, turn on electrical devices gradually (headlights first, then air conditioning) to avoid damaging the generator due to sudden heavy load impact.

References：

Key Notes

1. Content Source

   The content integrates general requirements for the installation and maintenance of Mitsubishi vehicle generators, typical technical parameters (such as bolt torque and belt deflection), electrical wiring specifications (B+/F/D+ terminals), and safety operation prohibitions (power-off operation, prohibition of load disconnection during operation, short-circuit prevention). It is compiled in combination with practical industry maintenance experience to facilitate on-site implementation.
2. Relationship with Original Factory Manuals

   The core provisions (including power-off operation, torque values, terminal markings, and voltage ranges) are consistent with those specified in Mitsubishi’s original factory maintenance manuals. However, this summary does not cite the manual number or page number corresponding to any specific vehicle model. To trace the exact source, you need to provide the specific vehicle model or generator model, and I can help locate the corresponding chapter and clauses in the original factory manual.
3. Verifiability

   The technical parameters specified in the documents, such as the voltage range (13.5–14.5 V), torque intervals, and belt deflection values, are universal industry standards for 12V vehicle alternators. All these parameters can be verified through actual measurements using tools such as a multimeter, torque wrench, and belt tension gauge.