Mitsubishi Pick-ups and Montero 1983-1995 Repair Guide

Alternator

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The alternator charging system is a negative (-) ground system which consists of an alternator, a regulator, a charge indicator, a storage battery, wiring connecting the components, and a fuse link wire.

The alternator is belt-driven from the engine. Energy is supplied from the alternator/regulator system to the rotating field through two brushes to two slip rings. The slip rings are mounted on the rotor shaft and are connected to the field coil. This energy supplied to the rotating field from the battery is called excitation current and is used to initially energize the field to begin the generation of electricity, the excitation current comes from its own output rather than the battery.

The alternator produces power in the form of alternating current. The alternating current is rectified by 6 diodes into direct current. The direct current is used to charge the battery and power the rest of the electrical system.

When the ignition key is turned on, current flows from the battery, through the charging system indicator light on the instrument panel, to the voltage regulator, and to the alternator. Since the alternator is not producing any current, the alternator warning light comes on. When the engine is started, the alternator begins to produce current and turns the alternator light off. As the alternator turns and produces current, the current is divided in two ways; part to the battery to charge the battery and power the electrical components of the vehicle, and part is returned to the alternator to enable it to increase its output. In this situation, the alternator is receiving current from the battery and from itself. A voltage regulator is wired into the current supply to the alternator to prevent it from receiving too much current which would cause it to put out too much current. Conversely, if the voltage regulator does not allow the alternator to receive enough current, the battery will not be fully charged and will eventually go dead.

The battery is connected to the alternator at all times, whether the ignition key is turned on or not. If the battery were shorted to ground, the alternator would also be shorted. This would damage the alternator. To prevent this, a fuse link is installed in the wiring between the battery and the alternator. If the battery is shorted, the fuse link is melted, protecting the alternator.

ALTERNATOR PRECAUTIONS



To prevent damage to the alternator and regulator, the following precautionary measures must be taken when working with the electrical system.

  1. Never reverse the battery connections. Always check the battery polarity visually. This is to be done before any connections are made to ensure that all of the connections correspond to the battery ground polarity of the truck.
  2.  
  3. Booster batteries must be connected properly. Make sure the positive cable of the booster battery is connected to the positive terminal of the battery which is getting the boost.
  4.  
  5. Disconnect the battery cables before using a fast charger; the charger has a tendency to force current through the diodes in the opposite direction for which they were designed.
  6.  
  7. Never use a fast charger as a booster for starting the truck.
  8.  
  9. Never disconnect the voltage regulator while the engine is running, unless as noted for testing purposes.
  10.  
  11. Do not ground the alternator output terminal.
  12.  
  13. Do not operate the alternator on an open circuit with the field energized. Make sure that all connections within the circuit are clean and tight.
  14.  
  15. Do not attempt to polarize the alternator.
  16.  
  17. Disconnect the battery cables and remove the alternator before using an electric arc welder on the truck.
  18.  
  19. Protect the alternator from excessive moisture. If the engine is to be steam cleaned, cover or remove the alternator.
  20.  
  21. Disconnect the battery terminals when performing any service on the electrical system. This will eliminate the possibility of accidental reversal of polarity.
  22.  
  23. Do not use test lamps of more than 12 volts for checking diode continuity.
  24.  

REMOVAL & INSTALLATION



Some vehicles may have an alternator cover that must be removed before removing this assembly. On some of the 4-cylinder engines, the A/C compressor assembly may have to be removed for working access.

2.0L and 2.6L Engines
WITHOUT AIR CONDITIONING

See Figure 1

  1. Turn ignition switch to OFF and disconnect both battery cables.
  2.  



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Fig. Fig. 1: Alternator assembly-2.0L & 2.6L engines without A/C

  1. Loosen the support bolt and adjusting bolt, and then shift the alternator toward the engine so belt tension is relaxed. Remove the belt. On some models it will be necessary to loosen the power steering pump and belt and then remove the pump from its brackets.
  2.  

  1. Note locations of all connectors. Make a drawing, if necessary. Unplug electrical connectors and unscrew fastening nuts for terminal type connectors. Clean any dirty connections.
  2.  
  3. Remove the adjusting bolt. Remove the nut from the rear of the mounting bolt. Note that in the next step, shims located between the alternator and the rear of the engine front cover may fall out. Retain these shims for re-use. Supporting the alternator, slide the mounting bolt out and then remove the unit from the vehicle.
  4.  

Some models may not be equipped with mounting shims.

To install:
  1. Position the assembly so that the mounting bolt can be inserted. If the same alternator is being re-used, insert the shims between the rear of the front cover and the rear hinge of the alternator body. Install the mounting bolt. If the alternator is a different one, you'll have to measure the clearance between the rear of the front cover and the section of alternator body that fits against it. Pull the alternator forward and use a flat feeler gauge. If the clearance exceeds 0.008 in. (0.2mm), insert shim(s) thick enough so there is a slight friction fit and they will not fall out when you let go of them. Put the shims between the front of the front cover and the rear of the front hinge on the alternator body. Make sure you have installed shims of adequate thickness (or that the clearance is within specification). Otherwise, the alternator body may become damaged. Install the mounting bolt if it is not already in place, and then install the mounting bolt nut loosely.
  2.  
  3. Install the adjusting bolt, and then loosely install the nut at the rear of it. Install the belt and tighten it as described in General Information & Maintenance . Tighten the adjusting bolt to 9-10 ft. lbs. (12-13 Nm) and the mounting bolt and nut to 15-18 ft. lbs. (20-24 Nm).
  4.  
  5. Reinstall the power steering pump and belt if it was removed. Adjust the belt to the proper tension. Tighten the power steering pump bolts to 18 ft. lbs. (24 Nm).
  6.  

WITH AIR CONDITIONING

See Figure 2

  1. Have the air conditioning system discharged by a trained and certified mechanic using a recovery/recycling machine.
  2.  
  3. Turn the ignition OFF and disconnect both battery cables.
  4.  


CAUTION
Only perform the following procedure AFTER the system has been discharged by a trained and certified mechanic. Doing otherwise may result in personal harm, environmental damage and damage to the vehicle's components.



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Fig. Fig. 2: Alternator assembly-2.0L & 2.6L engines with A/C

  1. Disconnect and label the discharge hose from the compressor. Cap the compressor port and plug the line immediately.
  2.  
  3. Disconnect and label the suction hose from the compressor. Cap the compressor port and plug the line immediately.
  4.  
  5. Disconnect and label the wiring connector to the compressor.
  6.  
  7. Loosen the belt tension adjuster, the lockbolt and the pivot bolt. Remove the belt, the lockbolt and the pivot bolt from the compressor. Support the compressor and remove it from the engine.
  8.  
  9. Loosen the upper and lower alternator bolts, release the belt tension for the alternator belt, pivot the alternator toward the engine and remove the belt from the alternator.
  10.  
  11. Label and disconnect the wiring connections at the back of the alternator.
  12.  
  13. Remove the upper bolt. Remove the lower bolt while supporting the alternator. Be prepared to catch the bolt shims, which will fall out when the bolt is removed. Remove the alternator from its mount.
  14.  

Some models may not be equipped with mounting shims.

To install:
  1. Install the alternator in its original position and insert the lower support bolt, but do not install the nut. Install the upper bolt just enough to hold the bolt in place.
  2.  
  3. Push the alternator forward (towards the front of the truck) and insert shims between the front leg of the alternator and the front case (mount). There should be enough shims to hold themselves in place when you let go. The alternator should still be movable with light pressure.
  4.  
  5. Tighten the upper and lower mounting bolts until they are finger-tight.
  6.  
  7. Install the alternator belt and adjust it to the correct tension. For this procedure, see General Information & Maintenance . Tighten the upper mounting bolt to 10 ft. lbs. (13 Nm) and the lower mounting bolt to 16 ft. lbs. (28 Nm). Connect the wiring to the alternator.
  8.  
  9. Reinstall the compressor. Install the belt over the pulley (making sure the belt is still correctly mounted on the other pulleys) and gently snug the belt by moving the compressor on its mounts. As soon as there is a little tension on the belt, tighten the compressor mounting bolts.
  10.  
  11. Set the belt to its final tension by tightening the adjuster screw on the compressor. Do not pry on the compressor to adjust the belt.
  12.  
  13. Connect the compressor wiring harness.
  14.  
  15. Remove the plugs and caps from the A/C fittings. Connect the suction hose to its port on the compressor and then connect the discharge hose. Tighten the fitting until finger-tight, making very certain they are clean and correctly threaded. Tighten the suction hose to 24 ft. lbs. (32 Nm) and tighten the discharge hose to 16 ft. lbs. (28 Nm).
  16.  
  17. Reconnect the cables to the battery.
  18.  
  19. Double check the drive belts for proper tension and adjust as necessary. If a belt is replaced during this procedure, it will need to be rechecked after 50-100 miles (80-160 km) of driving.
  20.  
  21. Take the vehicle immediately back to the mechanic to have the A/C system evacuated and recharged. The sooner this is done, the less chance of having the system become contaminated.
  22.  

Diesel Engine

See Figures 3 through 8

  1. Make certain the ignition switch is OFF and disconnect the battery cables.
  2.  
  3. Disconnect the cable from terminal B of the alternator.
  4.  



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Fig. Fig. 3: Alternator assembly-diesel engine



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Fig. Fig. 4: Remove the housing carefully



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Fig. Fig. 5: Always protect the shaft with tape



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Fig. Fig. 6: Correct installation of vanes



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Fig. Fig. 7: The housing must be pushed lightly in the correct direction



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Fig. Fig. 8: Do not tighten the support bolt if clearance A exceeds specifications. Damage to the alternator will result

  1. Remove the electrical connector from the back of the alternator.
  2.  
  3. Label and disconnect the oil hose, vacuum hose and return hose from the vacuum pump. Due to difficult access, it is usually easier to disconnect the oil return hose at the oil pan.
  4.  
  5. Remove the brace bolt and the support bolt nut; loosen the alternator.
  6.  
  7. Remove the drive belt from the alternator pulley.
  8.  
  9. Support the alternator and pump. Pull out the through-bolt and extract the unit from the vehicle.
  10.  
  11. Remove the vacuum housing bolts and then take out the housing.
  12.  
  13. Remove the rotor and vane from the shaft. Use great care not to damage the vanes or O-ring. Replace any piece showing signs of damage or wear.
  14.  
  15. Use a roll of black PVC (electrical) tape to wind around the shaft splines. This prevents possible damage to the oil seal while the rotor assembly is removed.
  16.  
  17. At this point the alternator may be further disassembled, if desired.
  18.  

To install:
  1. Coat the O-ring with a light coat of white grease to hold it in place. Make certain it does not protrude from the groove.
  2.  
  3. Install the vane(s) with the rounded end outward. Never re-use a vane with a damaged or chipped end. Remove the black tape from the splines just before the shaft is inserted.
  4.  
  5. Install the housing carefully. Gently push the housing in the direction shown in the illustration, this minimizes clearance at critical points. The performance of the pump is affected by the installation of the housing.
  6.  
  7. Tighten the bolts evenly while keeping light pressure.
  8.  
  9. If it is necessary to bench test the alternator after reassembly, make certain the pump is properly lubricated before turning the alternator. Take great care to insure the vacuum pump is never operated without lubrication.
  10.  
  11. Install the oil return hose to the vacuum pump and install the alternator in position. Once the unit is in place, it is impossible to attach the hose properly. Insert the through-bolt from the rear.
  12.  
  13. Install the drive belt onto the pulley; install the brace (upper) bolt.
  14.  
  15. Push the alternator towards the front of the engine and check for proper clearance between the alternator leg and the front case. If clearance is greater than 0.008 in. (0.2mm) insert spacers to reduce clearance.
  16.  


WARNING
If the support bolt is tightened without reducing the clearance, the alternator leg may be broken off.

  1. Connect the oil delivery tube, the vacuum hose and the electrical connector.
  2.  
  3. Connect the wiring to terminal B .
  4.  
  5. Adjust the belt tension correctly.
  6.  
  7. Connect the battery cables to their perspective terminals.
  8.  

2.4L and 3.0L (12 Valve) Engines

See Figures 9 and 10

  1. Turn ignition switch OFF and disconnect both battery cables.
  2.  
  3. Loosen the support bolt and the brace bolt, then loosen the adjusting bolt to shift the alternator toward the engine so that belt tension is relaxed. Remove the belt from the alternator pulley. If the alternator belt needs replacing it will be necessary to loosen the power steering pump and belt and then remove the pump from its brackets.
  4.  



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Fig. Fig. 9: Alternator assembly components and location-2.4L engines



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Fig. Fig. 10: Alternator assembly components and location-3.0L (12 valve) engines

  1. Note locations of all connectors. Make a drawing, if necessary. Unplug electrical connectors and unscrew fastening nuts for terminal type connectors. Clean any dirty connections.
  2.  
  3. Remove the adjusting bolt. Remove the nut from the rear of the support bolt. Supporting the alternator, slide the support bolt out and then remove the unit from the vehicle.
  4.  

To install:
  1. Position the assembly so that the support bolt can be inserted. Install the support bolt and attach the support bolt nut loosely.
  2.  
  3. Install the adjusting bolt assembly and brace bolt, and then loosely install the nut at the rear of the brace bolt. Install the belt and tighten it as described in General Information & Maintenance . Tighten the adjusting bolt to 9-10 ft. lbs. (12-13 Nm) and the support bolt and nut to 15-18 ft. lbs. (20-24 Nm).
  4.  
  5. Adjust the belt to the proper tension.
  6.  

3.0L (24 Valve) and 3.5L engines

See Figure 11

  1. Turn ignition switch to OFF and disconnect both battery cables.
  2.  

Since the alternator on these engines is located on the lower right hand (passenger) side of the engine, removal and installation of the alternator will require access from both the top and bottom of the engine compartment.

  1. Apply the parking brake and block the rear wheels.
  2.  
  3. Raise the front of the vehicle with a floor jack, using the proper frame positions.
  4.  
  5. Support the vehicle on the frame or transmission crossmember, with jackstands. Before working under the vehicle, make sure the vehicle is stable on the jackstands. If it is not, reposition the jackstands so that it is.
  6.  
  7. Loosen the support and brace bolts, then shift the alternator toward the engine so that belt tension is relaxed. Remove the belt from the alternator pulley. If the alternator belt needs replacing it will be necessary to loosen the power steering pump, along with any other belt-driven accessories, and remove the drive belts.
  8.  
  9. Note locations of all connectors. Make a drawing, if necessary, or label the wires. Unplug electrical connectors and unscrew fastening nuts for terminal type connectors. Clean any dirty connections.
  10.  
  11. Withdrawal the brace bolt, then remove the nut from the rear of the support bolt. Supporting the alternator, slide the support bolt out and then remove the unit from the vehicle.
  12.  

To install:
  1. Position the alternator in its original position and so that the support bolt can be inserted. Install the support bolt and attach the support bolt nut loosely.
  2.  
  3. Slide the brace bolt into place and loosely install its nut at the rear. Install the drive belt and tighten it as described in General Information & Maintenance . Tighten the support bolt and nut to 15-18 ft. lbs. (20-24 Nm).
  4.  
  5. Adjust the belt to the proper tension.
  6.  
  7. If any other accessories or their belts were removed for belt replacement, reinstall these components now.
  8.  
  9. Lower the vehicle. Remove the blocks from the wheels.
  10.  



Click image to see an enlarged view

Fig. Fig. 11: Alternator assembly components and location-3.0L (24 valve) and 3.5L engines

 
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