C-10 and C-12 Truck Engines Caterpillar

Test Tools For The Electrical System

Most of the tests of the electrical system can be done on the engine. The wiring insulation must be in good condition. The wire and cable connections must be clean, and both components must be tight. The battery must be fully charged. If the on-engine test shows a defect in a component, remove the component for more testing.

Refer to the service manual Testing And Adjusting Electrical Components, REG00636 for further information. This manual contains the following information:

• Complete specifications for the components of the starting circuits

• Procedures for the components of the starting circuits

• Complete specifications for the components of the charging circuit

• Procedures for the components of the charging circuit

Illustration 1	g00283565
4C-4911 Battery Load Tester

The 4C-4911 Battery Load Tester is a portable unit in a metal case. The 4C-4911 Battery Load Tester can be used under field conditions and under high temperatures. The tester can be used to load test all 6, 8, and 12 Volt batteries. This tester has two heavy-duty load cables that can easily be fastened to the battery terminals. A load adjustment knob is located on the top of the tester. The load adjustment knob permits the current that is being drawn from the battery to be adjusted to a maximum of 1000 amperes. The tester is cooled by an internal fan that is automatically activated when a load is applied.

The tester has a built-in LCD. The LCD is a digital voltmeter. The LCD is also an ammeter. The digital voltmeter accurately measures the battery voltage at the battery through wires for tracing. These wires are buried inside the load cables. The ammeter accurately displays the current that is being drawn from the battery.

Note: Refer to Operating Manual, SEHS9249 for more complete information for the use of the 4C-4911 Battery Load Tester.

Illustration 2	g00296441
8T-0900 Ammeter

The 8T-0900 Ammeter is completely portable. This ammeter is a self-contained instrument that measures electrical currents without breaking the circuit and without disturbing the conductor's insulation.

The ammeter contains a digital display that is used to monitor current directly within a range between 1 ampere and 1200 amperes. If an optional 6V-6014 Cable is connected between this ammeter and a digital multimeter, current readings can be viewed directly from the display of the multimeter. This can be accomplished only if the current is less than one ampere.

A lever opens the ammeter's jaws over a conductor. The conductor's diameter cannot be larger than 19 mm (.75 inch).

The spring loaded jaws close around the conductor for measuring the current. A trigger switch controls the ammeter. The trigger switch can be locked into the ON position or into the OFF position.

After the trigger has been working and the trigger is turned to the OFF position, the reading appears in the digital display for five seconds. This accurately measures currents in areas with a limited access. For example, these areas include areas that are beyond the operator's sight. For DC operation, an ammeter contains a zero control, and batteries inside the handle supply the power.

Note: Refer to Special Instruction, SEHS8420 for more information about using the 8T-0900 Ammeter.

Illustration 3	g00283566
6V-7070 Digital Multimeter

The 6V-7070 Digital Multimeter is a completely portable, hand-held instrument with a digital display. This multimeter is built with extra protection against damage in field applications. The multimeter is equipped with 7 functions and 29 ranges. The 6V-7070 Digital Multimeter has an instant ohms indicator. This indicator permits checking continuity for a fast inspection of the circuits. The multimeter can also be used for troubleshooting capacitors that have small values.

Note: Refer to Special Instruction, SEHS7734 for complete information for the use of the 6V-7070 Digital Multimeter .

Battery

Show/hide table

Never disconnect any charging unit circuit or battery circuit cable from the battery when the charging unit is operated. A spark can cause an explosion from the flammable vapor mixture of hydrogen and oxygen that is released from the electrolyte through the battery outlets. Injury to personnel can be the result.

The battery circuit is an electrical load on the charging unit. The load is variable because of the condition of the charge in the battery.

Use the 4C-4911 Battery Load Tester in order to test a battery that does not maintain a charge when the battery is active. Refer to Operating Manual, SEHS9249 for detailed instruction on the use of the 4C-4911 Battery Load Tester. See Special Instruction, SEHS7633 for the correct procedure and for the specifications to use when you test the batteries.

Charging System

The condition of charge in the battery at each regular inspection will show if the charging system operates correctly. An adjustment is necessary when the battery is constantly in a low condition of charge or a large amount of water is needed. A large amount of water would be more than one ounce of water per cell per week or per every 100 service hours.

When it is possible, make a test of the charging unit and voltage regulator on the engine, and use wiring and components that are a permanent part of the system. Off-engine testing or bench testing will give a test of the charging unit and voltage regulator operation. This testing will give an indication of needed repair. After repairs are made, perform a test in order to prove that the units have been repaired to the original condition of operation.

To check for correct output of the alternator, see the Specifications module.

Before the start of on-engine testing, the charging system and the battery must be checked according to the following steps.

1. The battery must be at least 75 percent (1.225 Sp Gr) of the full charge. The battery must be held tightly in place. The battery holder must not put too much stress on the battery.

2. Cables between the battery, the starter, and the engine ground must be the correct size. Wires and cables must be free of corrosion. Wires and cables must have cable support clamps in order to prevent stress on battery connections (terminals).

3. Leads, junctions, switches, and panel instruments that have direct relation to the charging circuit must give correct circuit control.

4. Inspect the drive components for the charging unit in order to be sure that the components are free of grease and oil. Be sure that the drive components have the ability to operate the charging unit.

Alternator Regulator

The charging rate of the alternator should be checked when the alternator is charging the battery too much. The charging rate of the alternator should also be checked when the alternator is not charging the battery enough. Refer to the Specifications module in order to find all testing specifications for the alternators and regulators.

No adjustment can be made to the rate of charge on the alternator regulators. If the rate of charge is not correct, a replacement of the regulator is necessary.

Tightening The Alternator Pulley Nut

Illustration 4	g00286495
Alternator (1) Ground terminal (2) Pulley nut

Illustration 5	g00283568
Tools for tightening the alternator pulley nut (1) 8T-9293 Torque Wrench (2) 8S-1588 Adapter (1/2 inch female to 3/8 inch male) (3) 2P-8267 Socket Assembly (4) 8H-8517 Combination Wrench (1-1/8 inch) (5) 8T-5314 Socket

Tighten the nut that holds the pulley to the following torque. ... 102 ± 7 N·m (75 ± 5 lb ft)

Electric Starting System

Use the multimeter in the DCV range to find starting system components which do not function.

Move the start control switch in order to activate the starting solenoids. The starting solenoid's operation can be heard as the pinion of the starting motor is engaged with the ring gear on the engine flywheel.

If a solenoid for a starting motor will not operate, it is possible that the current from the battery did not reach the solenoid. Fasten one lead of the multimeter to the connection (terminal) for the battery cable on the solenoid. Connect the other lead to a good ground. A zero reading indicates that there is a broken circuit from the battery. More testing is necessary when there is a voltage reading on the multimeter.

The solenoid operation also closes the electric circuit to the motor. Connect one lead of the multimeter to the solenoid connection (terminal) that is fastened to the motor. Connect the other lead to a good ground. Activate the starting solenoid and look at the multimeter. A voltage reading of the battery shows that the problem is in the motor. The motor must be removed for further testing. A zero reading on the multimeter shows that the solenoid contacts do not close. This indicates the need for repair to the solenoid or for an adjustment to the starting motor pinion clearance.

Perform a test. Fasten one multimeter lead to the connection (terminal) for the small wire at the solenoid and fasten the other lead to the ground. Look at the multimeter and activate the starting solenoid. A voltage reading shows that the problem is in the solenoid. A zero reading indicates that the problem is in the start switch or the wires for the start switch.

Fasten one multimeter lead to the start switch at the connection (terminal) for the wire from the battery. Fasten the other lead to a good ground. A zero reading indicates a broken circuit from the battery. Check of the circuit breaker and wiring. If there is a voltage reading, the problem is in the start switch or in the wires for the start switch.

Starting motors that operate too slowly can have an overload because of too much friction in the engine that is being started. Slow operation of the starting motors can also be caused by a short circuit, loose connections, and/or dirt in the motor.

To check for correct output of the starting motor and the starter solenoid, see the Specifications module.

Pinion Clearance Adjustment

When the solenoid is installed, make an adjustment of the pinion clearance. The adjustment can be made with the starting motor removed.

Illustration 6	g00442963
Typical connection for checking pinion clearance (1) Connector for motor terminal on solenoid to starter motor (2) SW terminal (3) Ground terminal

1. Install the solenoid without connector (1) from the "MOTOR" connections (terminal) on the solenoid to the motor.

2. Connect a battery that has the same voltage as the solenoid to "SW" terminal (2) .

3. Connect the other side of the battery to connector (3) .

4. For a moment, connect a wire from the solenoid connection (terminal), which is marked "MOTOR", to the ground connection (terminal). The pinion will shift to the crank position and the pinion will stay there until the battery is disconnected.

Show/hide table



Illustration 7	g00283574
Pinion clearance adjustment (4) Shaft nut (5) Pinion (6) Pinion Clearance

5. Push the pinion toward the end with the commutator in order to remove free movement.

6. Pinion clearance (6) must be 8.3 to 9.9 mm (.33 to .39 inch).

7. In order to adjust the pinion clearance, remove the plug and turn shaft nut (4) .

8. After the adjustment is completed, install the plug over adjustment nut (4). Install connector (1) between the motor terminal on the solenoid and the starting motor.