Alternator off car testing and Startermotor off car

Rotor winding to ground test:

Components: Two slip rings

Function: Receive power from regulator through two brushs (positive and negative) to make magnetic field between rotor and stator. Power receiver componet.

Set the meter on kilo Ohms. Place the Black lead on the center on the Slip ring. Red lead on center of the Rotor shaft. There should be no circuit between the rotor shaft and the slip ring. The meter should read infinity. If there is a circuit the rotor winding has shorted to ground and will need to be replaced.

The meter should  read infinity

Spec           Meter reading            Pass/Fail

Infinity             Infinity                       Pass

Rotor winding internal resistance test: 

Set the meter on Ohms, test for internal meter resistance by touching the two leads together. Place one end of each lead on the slip rings as indicated to obtain reading. 

The reading specification is 2 ohms to 6 ohms

Spec               Meter reading                Pass

2-6 ohms           3.6 ohms                     Pass

Testing stator winding resistance: 

Components: Coil wire teminal

Function: Power out put teminal

Set meter on Ohms, test for internal meter resistance by touching the two leads together. Select the common terminal (the one with the most wires attached) of the stator winding terminals A to D. Connect the Black lead to the common point. connect the Red lead to the other terminal one after the other.

Their resistance they should all be approximately the same from 0.0 ohm to 0.2 ohms.

Spec                                Meter reading                                Pass/Fail

0.0-0.2 ohms                          0.9                                             Pass

0.0-0.2 ohms                          0.8                                             Pass

0.0-0.2 ohms                          0.9                                             Pass

Testing the rectifier positive diodes:  Component: Rectifier (diode)

Function: Same as a diode, only let power go one way, change power from AC to DC.

Use the meter on diode test mode. Put the Black lead on B Terminal. Then touch the Red lead on each of the P terminals and record the reading.

The resistance should be low.

Results for Positive diode testing with Black lead on B.

No.      Spec     0.5 VD to 0.7 VD         Pass/Fail

1                      0.516                                Pass

2                      0.513                                Pass

3                      No reading                        Fail

4                      0.513                                Pass

No.     Spec   Infinity            Pass/Fail

1              Infinity                    Pass

2              Infinity                    Pass

3              Infinity                    Pass

4              Infinity                    Pass