Installation Method for Mitsubishi Pajero (Shanmao) 12V Generator

I. Pre-installation Preparation

1. Tools and Accessories

2. Safety and Verification Points

• Power-off Operation: Disconnect the negative terminal of the battery and take proper insulation measures to prevent short-circuit induced ablation of components during installation.

• Model Verification: Confirm that the generator model matches the original vehicle (common models for Pajero include MD366831, A003TG5391, etc.). Check that the generator rectifier, carbon brushes and pulley are free of damage.

• Cleaning Work: Clean oil stains and rust from the generator mounting bracket and the mating surface of the engine block to ensure tight assembly without gaps.

II. Core Installation Steps

1. Positioning and Fixing (Taking Pajero V93/V97 as an Example)

1. Lift the generator to the left side of the engine (the standard mounting position for Pajero generators), align it with the mounting holes on the bracket, insert the lower mounting bolts and pre-tighten them (do not fully tighten temporarily).

2. Adjust the angle of the generator to keep its pulley aligned on the same plane as the crankshaft pulley and water pump pulley. Insert the upper mounting bolts and adjusting arm bolts, and pre-tighten all bolts until they can no longer be turned by hand.

3. Tighten the bolts according to the factory torque specifications:

• Main mounting bolts: 22–28 N·m

• Adjusting arm bolts: 15–20 N·m

4. Apply medium-strength thread locker to the bolts to prevent loosening due to off-road vibrations.

2. Belt Assembly and Tension Adjustment

1. Install the new generator belt, routing it around the crankshaft pulley → water pump pulley → generator pulley → tensioner. Ensure the belt is free of twists and misalignment.

2. Use combination pliers to pull the tensioner adjusting arm and adjust the belt tension:

• Measure with a belt tension gauge; the standard tension is 80–120 N (a deflection of approximately 10–15 mm when pressing the middle of the belt by hand is acceptable).

3. Tighten the tensioner mounting bolt to a torque of 18–22 N·m.

3. Electrical Connection (Critical Anti-reverse Polarity)

1. B+ Terminal (thick wire post): Connect to the main cable of the battery positive terminal with a wire diameter of ≥ 6 mm². After crimping the terminal, apply conductive anti-rust paste, fasten it with a nut (torque: 10–12 N·m) and wrap it with insulating tape.

2. D+ Terminal (excitation wire): Connect to the charging indicator light on the instrument panel. Align the plug with the slot, push it firmly and lock the clip to prevent loosening.

3. Ground Terminal: The generator housing is grounded to the engine block via mounting bolts. If grounding is poor, add an additional ground wire of 2.5 mm², connecting one end to the housing and the other end to the exposed metal surface of the engine block.

4. Recheck and Reset

1. Inspect the wiring route: Ensure it avoids high-temperature components such as the exhaust pipe and turbocharger, as well as rotating components such as the fan and belt. Secure the cables with cable ties.

2. Reinstall the removed parts such as the engine decorative cover and air intake duct. Remove the insulation from the battery negative terminal and reconnect it securely.

III. Commissioning and Testing

1. Pre-startup Inspection

1. Use a multimeter to measure the battery voltage: The static voltage should be 12.4–12.7 V.

2. Check that the generator belt has no deviation or interference, and the pulley rotates smoothly without jamming or abnormal noise when turned by hand.

2. Post-startup Verification

1. Idle Speed Test: Start the engine. At idle speed, the charging voltage should be 13.5–14.5 V (complying with the 12V system standard). The charging indicator light on the instrument panel should turn off; if it remains on, there is a fault in the circuit or excitation system.

2. Load Test: Turn on high-power electrical equipment such as headlights and air conditioners. The voltage should remain between 13.0–14.2 V without significant drop, and the generator should operate without sharp noise or abnormal vibration.

3. Belt Inspection: After 5 minutes of operation, touch the pulley to ensure it is not overheated, and check that the belt has no slipping or squealing noise.

4. Key Precautions for Installing Mitsubishi Pajero (Shanmao) 12V Generator

5. Throughout the entire installation process, focus on four core aspects: power-off safety, mechanical assembly, electrical connection, and commissioning operation, so as to avoid problems such as generator ablation, abnormal charging, and belt failure. Specific requirements are as follows:

6. 1. Power-off Operation is the Top Priority

7. Disconnect the negative terminal of the battery and take proper insulation measures before installation. It is strictly forbidden to plug or unplug wires with power on, or test the generator by short-circuiting its terminals, to prevent short-circuit damage to the rectifier, voltage regulator, and even the vehicle-mounted ECU.

8. 2. Precision Requirements for Mechanical Assembly

9. Thoroughly clean oil stains and rust from the mating surface of the generator mounting bracket and the engine block to ensure tight fit without gaps. Apply medium-strength thread locker to the mounting bolts, and tighten them diagonally according to the factory torque specifications (main bolts: 22–28 N·m; adjusting arm bolts: 15–20 N·m). Loose bolts will cause belt deviation and bearing wear, while over-tightening may break the bracket or deform the generator housing.

10. Ensure the generator pulley is aligned on the same plane as the crankshaft pulley and water pump pulley to avoid twisted stress on the belt. After installing a new belt, calibrate the tension with a tension gauge (standard tension: 80–120 N). A deflection of approximately 10–15 mm when pressing the middle of the belt by hand is optimal. Insufficient tension will cause slipping and squealing, while excessive tension will accelerate wear on bearings and the belt.

11. The generator brackets of 3-door short-wheelbase and 5-door long-wheelbase Pajero models are different. Do not mix accessories of different models, otherwise installation misalignment or belt interference will occur.

12. 3. Error-proof Specifications for Electrical Connection

13. Polarity must never be reversed: The B+ terminal must be connected to the main positive cable of the battery (wire diameter ≥ 6 mm²), and the D+ terminal to the charging indicator light on the instrument panel. Reversing the positive and negative poles will directly burn out the core components of the generator.

14. Crimp the wire terminals securely and apply conductive anti-rust paste. Tighten the nut of the B+ terminal to a torque of 10–12 N·m to prevent loosening and overheating. Align the plug with the slot and lock it firmly to avoid loosening due to off-road vibrations.

15. The generator housing is grounded to the engine block via mounting bolts. If poor grounding occurs due to excessively thick paint on the engine block, add an additional ground wire (≥ 2.5 mm²), connecting one end to the exposed metal of the housing and the other end to the metal surface of the engine block. Otherwise, excitation faults and unstable charging voltage will occur.

References：

Core Sources and Basis

1. Mitsubishi Factory Service Manual (FSM)

   It takes the chapter on charging system/generator removal and installation for Pajero V93/V97 (equipped with 6G72/6G75 engines) as the core reference. This manual covers key parameters including power-off procedures, bolt torque values, belt tension standards, terminal definitions (B+/D+), and charging voltage ranges, serving as the fundamental source of these specifications.
2. Industry-wide General Specifications and Safety Standards

   These include universal requirements for 12V vehicle electrical systems such as anti-reverse polarity protection, wire diameter and routing protection, belt tension and alignment criteria, and grounding reliability requirements. These standards are applicable to generator replacement for the vast majority of passenger vehicles.
3. Practical After-sales Maintenance Experience

   This part supplements the manual specifications with on-site operational insights, such as bolt anti-loosening measures for Pajero’s off-road operating conditions, routing guidelines to avoid high-temperature and rotating components, and troubleshooting tips for common faults (e.g., persistent charging indicator light, belt slipping, abnormal voltage output).

4.