Component Tests

Starter

Load Test

Conduct this test if the starter motor (11002) cranks slowly and it is desired to compare current to specifications.

1. Connect Rotunda Starting and Charging Tester 078-00005 or equivalent. Make sure that current is not flowing through ammeter and heavy-duty carbon pile rheostat portion of circuit (rheostat at maximum counterclockwise position).

   NOTE: Make sure ignition switch (11572) is in the OFF position and S-terminal connector has been removed so engine does not start.

2. Place transmission in NEUTRAL or PARK. Crank engine with ignition switch OFF, and determine exact reading on voltmeter. This test is accomplished by disconnecting push-on connector S at starter solenoid (11390) and by connecting a remote control starter switch from positive battery terminal to S-terminal of starter solenoid .

3. Stop cranking engine, and reduce resistance of carbon pile until voltmeter indicates same reading as that obtained while starter motor cranked the engine. The ammeter will indicate starter current draw under load. Check this with value listed in Starter Specifications.
   
   
   
   

Voltage Drop Tests

If the starter motor cranks slowly and the battery (10653) is satisfactory, there may be a malfunction of the starter motor or in the cranking circuit wiring. To determine if the problem is in the wiring, a voltage drop test must be performed.

These tests are performed to determine if there is excessive resistance in the starter motor circuit. Always make the volt-ohmmeter connections at the component terminal rather than at the cable wiring end connector. Making a connection at the wiring end connector could result in false readings because the meter will not pick up a high resistance between the wiring connector and the component.

Motor Feed Circuit

1. Prevent the engine from starting by disconnecting the ignition coil (12029) .

2. Connect a remote starter switch between the starter solenoid S-terminal and the battery positive (+) terminal.

3. Connect Rotunda Digital Volt-Ohmmeter 007-00001 or equivalent positive lead to the battery positive (+) post. Connect Rotunda Digital Volt-Ohmmeter 007-00001 or equivalent negative lead to the solenoid M-terminal.

4. Engage the remote starter switch. Read and record the voltage. The voltage reading should be 0.5 volt or less.

5. If the voltage reading is higher than this, indicating excessive resistance, move the volt-ohmmeter negative lead to the starter solenoid B-terminal and repeat the test. If the voltage reading at the B-terminal is lower than 0.5 volt, the concern is either in the connections at the solenoid or in the solenoid contacts.

6. Remove the cables from solenoid B-, S-, and M-terminals. Clean the cables and connections and reinstall the cables to the proper terminals. Repeat Steps 1 through 5 above. If the voltage drop reading is still higher than 0.5 volts when checked at the M-terminal or lower when checked at the B-terminal, the concern is in the solenoid contacts. Remove and replace the starter motor or starter solenoid , if available.

7. If the voltage reading taken at the solenoid B-terminal is still higher than 0.5 volt after cleaning the cables and connections at the solenoid, the concern is either in the positive (+) battery cable connection, or in the positive battery cable itself.

8. By moving the volt-ohmmeter negative lead toward the battery and checking each mechanical connection point, the excessive voltage drop can be located. When the high reading disappears, the last mechanical point that was checked is the concern.
   
   
   
   

Motor Ground Circuit

A slow cranking condition can be caused by resistance in the ground or return portion of the cranking circuit. Check the voltage drop in the ground circuit as follows:

1. Prevent the engine from starting by disconnecting the ignition coil .

2. Connect a remote starter switch between the starter solenoid S-terminal and the battery positive (+) terminal.

3. Connect a Rotunda Digital Volt-Ohmmeter 007-00001 or equivalent positive lead to the starter motor housing (connection must be clean and free of rust or grease). Connect Rotunda Digital Volt-Ohmmeter 007-00001 or equivalent negative lead to the negative (-) battery terminal.

4. Engage the remote starter switch and crank the engine. Read and record the volt-ohmmeter reading. The reading should be 0.2 volt or less.

5. If the voltage drop is more than 0.2 volt, clean the negative cable connections at the battery and body connections, and retest. If the voltage drop is still too high, perform the following test:
   
   
   
   

Individual Cable

The resistance of any cable can be checked in the same manner by using Rotunda Digital Volt-Ohmmeter 007-00001 or equivalent.

1. Determine which way the current is flowing in the cable. Connect Rotunda Digital Volt-Ohmmeter 007-00001 or equivalent positive lead to the end of the cable nearest battery positive.

2. Connect Rotunda Digital Volt-Ohmmeter 007-00001 or equivalent negative lead to the terminal at the other end of the cable.

3. Crank the engine and observe Rotunda Digital Volt-Ohmmeter 007-00001 or equivalent. The voltage reading should be 0.2 volt or lower. If the voltage drop is too high, clean the terminal ends. Retest, and if still high, replace the cable.

Motor Pinion Test

1. Turn the pinion by hand and hold the overrunning clutch. Replace the starter drive (11350) if the pinion turns in both directions or does not turn.
   
   
   
   

No-Load Test

The starter no-load test will uncover such conditions as open or shorted windings, or rubbing starter motor armature (11005) . The starter motor can be tested, at no-load, on the test bench only.

 CAUTION: Make sure that the starter motor is securely mounted in bench vise while energizing, as starter motor will move or jump.

1. Make test connections with Rotunda Starting and Charging Tester 078-00005 or equivalent cables connected to starter motor , large enough to carry high current (the same as in the vehicle). The starter motor will run at no-load. Be sure that no current is flowing through ammeter (rheostat at maximum counterclockwise position). Determine exact reading on voltmeter.
   
   
   
   

2. Disconnect starter motor from battery . Then, reduce resistance of rheostat until voltmeter indicates same reading as that obtained while starter motor was running. The ammeter will indicate starter motor no-load current draw. Refer to Starter Specifications at the end of this Section for a comparative value.

3. If current exceeds specification, check for rubbing starter motor armature , bent output shaft (11355) , binding bushings, or shorts in starter motor armature , or brush holder (11061) .
   
   
   
   

Armature

Open Circuit Test

An open circuit starter motor armature may sometimes be detected by examining the commutator for evidence of burning. A burn spot on the commutator is caused by an arc formed every time the commutator segment, connected to the open circuit winding, passes under a brush.

Grounded Circuit Test

This test will determine if the winding insulation has been damaged, permitting a conductor to touch the frame or starter motor armature core. To determine if the starter motor armature windings are grounded, check with a Rotunda Digital Volt-Ohmmeter 007-00001 or equivalent. Infinite resistance indicates a normal condition.

Starter Solenoid

Ensure that the starter solenoid is isolated electrically from the starter motor . Using a Rotunda Digital Volt-Ohmmeter 007-00001 or equivalent, check for continuity between S-terminal and M-terminal, and between S-terminal and ground ( starter frame and magnet (11075)). If there is no continuity, the following conditions may exist:

• Open wire; replace starter solenoid .
• Ice, dirt or other foreign material preventing contact; service as necessary.

Solenoid S-Terminal Circuit Resistance

Using Rotunda Digital Volt-Ohmmeter 007-00001 or equivalent, check the resistance of the entire S-terminal circuit, including all the switches, wires, and connections. Resistance should be less than 0.08 ohm.

Solenoid M-Terminal

1. Using Rotunda Digital Volt-Ohmmeter 007-00001 or equivalent, check for continuity between the solenoid M-terminal and the solenoid housing.

2. If there is no continuity, replace the starter solenoid .