Car Alternator For MITSUBISHI TRUCK MONTERO Pajero II 6G72 6G74 12v 100a A3TA1191 MD317119 MD350609

I. Core Safety Prerequisites (Mandatory Before Installation)

• Ensure the vehicle is turned off. Disconnect the negative (-) battery cable.

• Wait at least 3-5 minutes to allow the ECU and capacitors to discharge, preventing damage to control units from short circuits during operation.

• Confirm the new alternator part number matches the original (Mitsubishi OEM parts usually follow the MD3xxx or A003TG... series).

• Check that the rectifier and pulley rotate smoothly, and inspect the pulley grooves for cracks.

• Socket wrench set (10mm, 12mm, 14mm), Torque wrench, Extension bars, Phillips screwdriver, Multimeter.

II. Mechanical Installation Steps (Including Critical Torque Values)

• Mounting Position: The alternator is typically located on the right side of the engine (when facing the front of the vehicle).

• Align Brackets: Hook the alternator onto the lower fixed bracket pin/hole.

• Install Adjustment Arm: Pass the top adjusting bar through the mounting hole.

• Pre-tighten Bolts:

• Install the bottom mounting bolt and the top adjustment arm bolt.

• Note: Do not fully tighten at this stage. Only hand-tighten to allow the alternator to pivot up and down for subsequent belt tension adjustment.

• Install Belt: Route the alternator belt around the crankshaft pulley, water pump pulley, A/C compressor pulley (if equipped), and the alternator pulley.

• Adjust Tension:

• Rotate the top adjustment nut clockwise to move the alternator outward and tension the belt.

• Tension Standard (经验法 - Empirical Method): At the midpoint between the alternator and the water pump (or crankshaft), press the belt firmly with your thumb. The deflection should be between 10mm - 15mm (New belts should be slightly tighter; old belts slightly looser).

• Tension Standard (Instrument Method): Mitsubishi factory recommendation is approximately 500-700 N (Depending on belt type: 4PK/6PK).

• Tighten Bolts (Critical Torque):

• While maintaining tension, first tighten the bottom mounting bolt.

• Then tighten the top adjustment arm bolt.

• Standard Torque: Mounting bolts are typically 35 - 42 N·m (Specific torque depends on model year; V73 is commonly 39 N·m).

• Warning: Never start the engine before bolts are fully tightened, as the belt may fly off, causing a serious accident.

III. Electrical Connections (Sequence is Critical)

• Align the voltage regulator plug (usually 2 or 3 holes) with the alternator socket and insert it until a "click" is heard to confirm locking.

• Note: Some Pajero models (e.g., those with idle-up function) have 3 wires. Ensure the pins are not inserted incorrectly.

• Connect the thick positive battery cable to the alternator's B+ (or M) terminal.

• Install a flat washer and a spring washer (or lock washer).

• Tighten the nut to 8 - 10 N·m to ensure good contact and prevent loosening.

• Mandatory: Install the red insulating protective cap to prevent short circuits from falling metal tools.

• After confirming all wiring is correct, reconnect the negative battery cable last.

IV. Functional Testing and Verification

• Double-check that the belt is seated correctly in the pulley grooves without misalignment.

• Start the engine and let it idle.

• Listen: The alternator should operate without a high-pitched squeal (belt slipping) or heavy mechanical grinding noise.

• Check Gauges: The dashboard "Charge Indicator Light" (battery icon) should turn off immediately after startup.

• Red probe on battery positive (+), Black probe on battery negative (-).

• Idle Voltage: Should be between 13.5V - 14.5V.

• Load Voltage: With headlights and A/C turned on, voltage should remain above 13.0V and not drop below 12.5V.

I. Electrical System Safety (Core Taboos)

• Action: The negative battery terminal must be completely disconnected before installing the alternator.

• Consequence: The Pajero's alternator B+ terminal is directly connected to the battery positive and is typically exposed in the engine bay. If the B+ cable is installed while the battery is connected, a wrench slipping and touching the engine block (ground) will create a short circuit current of several thousand amps. This can cause the wrench to melt, the wiring harness to ignite, or even an explosion of the battery.

• Action: It is absolutely forbidden to short the B+ terminal and the D+ (excitation) terminal with a screwdriver to test if the alternator is generating electricity.

• Consequence: Modern Pajeros (especially V93/V97) are equipped with integrated voltage regulators. This old-fashioned "flashing" test will instantly destroy the zener diode inside the regulator, directly damaging the new alternator.

• Detail: The nut for the B+ main power terminal on the Pajero alternator is usually 8mm or 10mm.

• Hazard: If this terminal is loose, high current will generate high-temperature arcing, leading to burning and corrosion of the terminal post.

• Requirement: A flat washer and a spring washer (or lock washer) must be used, tightened to the specified torque (typically 8-10 N·m). Always reinstall the factory-supplied red insulating protective cap to prevent short circuits from water ingress during off-road driving.

I. Core Authoritative Sources (Mitsubishi OEM System)

• Applicable Chapters:

• Section PG (Power Plant): Alternator → Removal/Installation.

• Section SC (Starting & Charging System): Alternator → Electrical Connections.

• Core Parameters: Mounting bolts (35-42 N·m), B+ terminal (8-10 N·m), belt tension, voltage regulator protection logic, and idle-up signal wire definitions.

• Access: Mitsubishi MMC official ESM (Electronic Service Manual) subscription, authorized dealer DMS systems, or model-specific physical manuals.

• Search Path: Manual Table of Contents → Engine → Power Plant → Alternator → Installation Notes; or Charging System → Alternator → Torque Specifications.

• Applicable Topics: Cases involving unstable charging after alternator installation, belt misalignment, abnormal voltage drop, and ECU/Dashboard charge light false alarms.

• Supplementary Points: Includes pulley alignment specifications for 6G72/6G75 engines, V93/V97 idle-up signal circuit troubleshooting, and silicone oil fan interference handling.

• Access: Authorized dealer technical departments, third-party repair databases (e.g., Alldata, Mitchell1).

• Search Path: TSB Database → Search for keywords like "Alternator Installation," "Charging System No-Charge," or "Voltage Drop."

• Key Positioning Points: Installation specifications including rectifier pre-checks, overrunning clutch clearance, and insulation resistance standards (≥1 MΩ).

• Access: Manufacturer official websites, authorized dealer technical documentation.

• Search Path: Mitsubishi Electric/Denso Alternator Service Guide → Installation Precautions → Mechanical & Electrical Checks.

II. General Standards and Industry Norms

• SAE J563: 12V Charging system electrical safety and performance standard, covering voltage drop (≤0.2V), terminal insulation, and ground circuit requirements.

• ISO 15500: Road vehicle alternator installation and maintenance specifications, including mechanical alignment, torque control, and wiring harness protection.

• Mitsubishi Service Data and Specifications (SDS): Defines factory parameters such as alternator no-load current, belt tension, and insulation resistance.