Alternator and Regulator

WARNING

(3) With positive meter probe connected to

black wire No. 2 and negative probe connected to

Clean all parts in a well-ventilated area.

the dark blue wire (center tap), the resistance

Avoid inhalation of solvent fumes and

should be approximately 0.50 ohm.

prolonged exposure of the skin to

cleaning solvent. Wash exposed skin

(4) With the positive meter probe connected

to black lead No. 1 and negative probe connected to

thoroughly.

the red lead, the resistance should be 2.75 ohms.

(2) Flush the metallic parts with a solution of

water and baking soda to neutralize any spilled

(5) With the positive meter probe connected

to black lead No. 2 and negative probe connected to

acid. Remove any greasy or gummy deposits with a

cloth dampened with cleaning solvent (fed. spec. P-

the red lead, the resistance should be 1.75 ohms.

D-680).

(6) If any of these tests indicate a short or

open circuit, the stator must be replaced. Refer

(3) Inspect all parts for cracks, corrosion,

d a m a g e d paint, stripped threads, and other

trouble to direct and general support maintenance.

damage. Touch up damaged paint. Replace

(7) Any connection between a lead and engine

ground should indicate infinite resistance. Any

damaged parts.

(4) If necessary, s e r v i c e the battery as

other reading indicates that a short circuit exists

directed in subparagraph a above.

and the stator must be replaced.

d. Reassembly and Installation. Refer to figure

c. To check the rectifier module, which you can

4-8 and install the battery, battery box, and cables

distinguish from the regulator by the two black

in the reverse order of removal. After installation,

leads, use a multimeter and static check continuity

be sure that you coat the battery terminals with

as follows:

G A A lubricant or petroleum jelly to prevent

(1) With the positive meter probe connected

to the engine ground and the negative probe

corrosion.

connected to black lead No. 1, the meter should

4-24. Alternator and Regulator

indicate 5 to 15 ohms resistance.

Testing of the alternator and components shall be

(2) With the positive meter probe connected

done while the parts are mounted on the engine.

to black lead No. 1 and the negative probe con-

The rectifier and regulator modules and the

nected to the engine ground, the resistance shall be

isolation diode are grounded to the engine so that

infinite. Any other reading indicates that a short

they cannot be tested while mounted at a remote

circuit exists and the rectifier must be replaced.

location. Before conducting the following tests to

Report trouble to direct and general support

determine the condition of the components, check

maintenance.

to insure that you have good continuity between the

(3) With the positive meter probe connected

modules and the engines. These are static tests

to the engine ground and the negative probe

which do not require that you run the engine.

connected to black lead No. 2, the resistance shall

Disconnect battery leads and uncouple the con-

be 5 to 15 ohms.

nectors that connect the modules to the stator leads.

(4) With the positive meter probe connected

a. You can check the operation of the battery

to black lead No. 2 and the negative probe con-

charging system by observing the ammeter. The

nected to the engine ground, the resistance shall be

ammeter should indicate a high charging rate

infinite. Any other reading indicates that a short

immediately after starting. After a few minutes the

circuit exists and the rectifier must be replaced.

ammeter should return to near zero. If the ammeter

d. Check the regulator module, which you can

does not operate in this manner or if it indicates a

distinguish from the rectifier module by the red and

discharge rate, perform checks in subparagraphs b

black leads. Using a multimeter, all continuity

through d below.

checks shall indicate infinite resistance. Any other

b. T o c h e c k f o r s t a t o r c o n t i n u i t y , u s e a

reading indicates that a short circuit exists and the

multimeter with R x 1 scale (minimum sensitivity

regulator must be replaced. Report trouble to direct

of 20,000 ohm / volts), and check as follows:

and general support maintenance. The multimeter

(1) With positive meter probe connected to

probe connections shall be as follows:

black wire No. 1 and negative probe connected to

(1) Positive probe connected to red lead.

black wire No. 2, the multimeter should indicate

Negative probe connected to engine ground.

approximately 1.00 ohm resistance. Replace stator

(2) Positive probe connected to engine

if multimeter indicates a short (no resistance) or

ground.

open (infinite resistance) circuit.

Negative probe connected to red lead.

(2) With positive meter probe connected to

(3) Positive probe connected to red lead.

black wire No. 1 and negative probe connected to

Negative probe connected to black lead.

the dark blue wire (center tap), the resistance

should be approximately 0.50 ohm.

4-18