SPECIFICATIONS

Vehicle Systems Testing And Adjusting

Shunt Field Tests

Open Circuit Test

Shunt Coil Open Circuit Test

1. Put the Function/range Switch of the digital multi-

meter on the 200 ohm resistance (A) scale.

2. Put the test leads between the shunt terminals.

3. The resistance must be approximately 5 to 10

ohms. If the resistance is more than this, it is an

indication of corrosion on the terminals or an open

shunt coil.

Ground Test

Shunt Coil Ground Test

1. Put the Function/Range Switch Switch of the

digital multimeter on the 20M resistance (A) scale.

2. Put one test lead to either shunt coil terminal. Put

the other test lead to the motor housing. There

must be more than one megohm resistance.

Check both shunt coil terminals.

3. If the indication is less than one megohm, the

shunt coil is grounded and must be replaced.

Brush Holder Test

(1) Brush holder. (2) End bell.

1. The brush holders are mounted on an insulator at

the commutator end of the motor. Make a visual

inspection of the brush holders and insulator.

2. Put digital multimeter. Function/Range Switch on

the 200 ohm resistance (½) scale. Put one test

lead to brush holder (1) and the other test lead to

the end bell (2). The meter must show overload

(OL).

3. Check each brush holder. If meter reading is low,

the brush holder is grounded. Replace the

insulator.

Tools Needed

Digital Multimeter Or Equivalent 1

Tools Needed

Digital Multimeter Or Equivalent 1