PUMP GP-GOV & FUEL INJ 7N1737 - Caterpillar

Procedure For Testing A 103-0703 Zener Diode
Reference: Schematic, RENR3125, "Solid State Magnetic Controller for Material Handlers Electrical System"The diode is located on the terminal strip in the control panel. The location of the diode on the terminal strip is shown in Illustration 1.The diode is referenced as a transient voltage suppressor in Schematic, RENR3125. The diode is referenced in the circuit TVS109 that is on the schematic.A digital multimeter is used in order to test the diode. The normal failure mode for a 103-0703 Zener Diode is shorted. Make sure that the multimeter is set on the diode test scale. Do not select the ohmmeter scale on the multimeter.
Before making any adjustments to the generator the engine must be shut off and the main disconnect switch on the controller must be in the off position. Personal injury can occur.Close all controller panel doors before the generator is started. Personal injury can occur.Never handle the leads to the magnet unless the generator is stopped and the main disconnect switch on the controller is in the off position. Personal injury can occur.
Remove 103-0703 Zener Diode from the circuit.
Connect the digital multimeter positive lead to one end of the 103-0703 Zener Diode.
Connect the digital multimeter negative lead to the opposite end of the 103-0703 Zener Diode .
Record the reading.
Reverse the multimeter leads on the ends of the diode.
Record the reading.The multimeter display will show an overload OL in both readings if the diode is good. The multimeter will read a very low voltage (0 volts to 0.6 volts) in Step 4 or Step 6 if the diode is faulty.
Illustration 1 g00789185
Terminal Strip In The Control Panel (A) 103-0703 Zener Diode