PULLEY-CRANKSHAFT 7W3773 - Caterpillar

Illustration 1 g00931045
Typical wiring schematic for an alternator
(A) Terminal "B+"
(B) Terminal "D+"
(C) Terminal "W"
(D) Ground
(1) Electrical switch
(2) Dash light
(3) Ignition switch
(4) Battery Warning Lamp Does Not Illuminate
The warning lamp for the charging system should illuminate when the ignition switch is in the ON position. Follow the steps below in order to test your system.
Table 1
Required Tools
Part Number Part Name Qty
6V-7070 Digital Multimeter 1
Check the light bulb. Replace the light bulb if the filament is broken.
Use the 6V-7070 Digital Multimeter to Check the battery voltage. Check the battery voltage with the ignition switch OFF.
Check the voltage between the terminal (A) and ground. The measured voltage should equal the battery voltage.
Turn the ignition switch to the ON position. Check the voltage between terminal (B) and ground. If the voltage is more than 2 Volts the alternator needs to be replaced. Warning Light is On When the Engine is Running
Start the engine and run the engine at fast idle.
Measure the voltage between terminal (A) and ground.
Measure the voltage between terminal (B) and ground.
The measured voltage for terminal (A) and terminal (B) should be 13 to 15 volts for a 12 volt system. The measured voltage for terminal (A) and terminal (B) should be 26 to 30 volts for a 24 volt system.
If the voltages do not match replace the alternator.
Increase the engine to full throttle. Turn an electrical load ON.
Measure the voltage between terminal (A) and ground.
Measure the voltage between terminal (B) and ground.
The measured voltage for terminal (A) and terminal (B) should be 13 to 15 volts for a 12 volt system. The measured voltage for terminal (A) and terminal (B) should be 26 to 30 volts for a 24 volt system.
Replace the alternator if the voltage does not match.