SPECIFICATIONS

Vehicle Systems Testing And Adjusting

Pitch Bar-Marks on the Commutator Surface

Pitch bar-marks cause low or burnt marks on the

commutator surface.

Field Coil and Terminal Tests

Open Circuit Test

1. Put the digital multimeter Function/Range Switch

on the 200 ohm resistance (A) scale.

2. Put one test lead to each outer field terminal

(P1,P2).

3. The resistance must be less than one ohm. If the

resistance is too high, it is an indication of corro-

sion on the terminals or an open field coil.

Brush Test

(1) Field terminal. (2) Brush leads.

4. Put one test lead to one of outer field terminals

(1). Put the other test lead to each of brush leads

(2) that connect to the brush holders. There must

be continuity to two of the leads with a resistance

of less than 1 ohm.

5. Put one test lead the other outer field terminal.

There must be continuity from this field terminal to

the other two brush holder leads.

Ground Test

(1) Field terminal. (2) Motor housing.

1. Put the digital multimeter Function/range Switch

on the 20M resistance (A) scale.

2. Put one test lead to either outer field terminal (1)

and the other test lead to motor housing (2). There

must be more than one megohm resistance.

3. If there is a measurement of less than one

megohm, it can be caused by wet insulation on

the field windings or excessive brush dust in hous-

ing. Heat the motor at 88C(190D) until the resis-

tance goes above one megohm. If the resistance

does not go above one megohm, the shell and

field assembly must be replaced.

Tools Needed

Digital Multimeter Or Equivalent 1

IDCS158S