Description & Theory Of Operation: Testing: Starters

CAUTION: Before making any starter tests, place transmission in Park or Neutral and apply parking brake to avoid injury if vehicle were to move.

NOTE: Many starters require 10 1/2 volts at the starter terminals to crank properly. Before any starter tests are made, check battery and battery cables. Battery must be fully charged with no shorted or dead cells. If battery cannot provide the correct voltage it must be recharged or replaced. Battery cables must be correct gauge and connections must be clean and tight. Always replace cables when necessary with the exact length and diameter cable. Installing a longer or smaller diameter cable increases the resistance permitting less voltage to be delivered to the starter. Replacement cable should be same length and preferably No. 4 gauge.

When the starting switch is closed, you can expect one of five things to occur if the starting circuit is defective:

STARTER SWITCH CLOSED AND NOTHING HAPPENS
This indicates that current is not reaching the solenoid and switch contacts are not closing to complete circuit. The problem lies in part of the circuit leading up to the solenoid, in the solenoid or starter relay.

To check this condition, connect a jumper lead directly between positive battery terminal and ignition switch terminal of solenoid or starter relay. If engine cranks, the circuit is open somewhere between battery and solenoid. If solenoid switch does not close, solenoid or starter relay is defective and must be replaced (See TESTING - Solenoids , described later in this story).
SOLENOID CONTACTS "CLICKED" BUT STARTER MOTOR DID NOT OPERATE
This indicates problem is within starter motor. If solenoid switch contacts close and switch begins to chatter, there is low voltage at the starter because of low battery charge, or high resistance in circuit, or an open in the hold-in winding of the solenoid. If battery charge is good, clean and inspect battery cable to solenoid connections. If solenoid and cable connections are good, problem is in starter motor and it must be replaced.
STARTER MOTOR RAN BUT DID NOT TURN OVER ENGINE
Problem is either in the shifting of the drive assembly into mesh, a broken armature shaft, or a dirty or faulty drive assembly. All of these require starter replacement.
STARTER MOTOR TURNED ENGINE OVER SLOWLY OR ERRATICALLY
Problem may be in starter motor or drive assembly. Before removing the starter motor, a voltage drop test should be made. A voltage drop test will locate any high resistance connections, shorted or grounded windings which would affect the starter motor.

With the engine cranking, connect a voltmeter between battery positive post and starter motor terminal. Voltage drop should be approximately 0.3 - 0.6 of a volt, not exceeding 0.6 of a volt. Then connect the voltmeter between battery ground post and starter frame, voltage drop should be approximately 0.1 - 0.3 of a volt, not exceeding 0.3 of a volt. If no high resistance connections are found, inspect pinion drive and flywheel ring gear. If either gear is damaged, starter or flywheel ring gear must be replaced.

NOTE: For exact voltage drops, see manufacturer's test specifications.

Fig 1: Solenoid Wiring Circuit
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Fig 2: Armature Shaft & Drive Assembly
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Fig 3: Voltage-Drop Test
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Fig 4: Solenoid & Drive Assembly (Disengaged)
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Fig 5: Disconnecting Battery Cable For Safety
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Fig 6: Delco-Remy Field Housing Bolt Installation (Late Models)
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ENGINE STARTS BUT MOTOR DRIVE ASSEMBLY DOES NOT DISENGAGE
This indicates a faulty drive assembly, solenoid pull-in windings, solenoid contacts, broken return spring, GM shims left out or solenoid control circuit which will not let drive assembly retract and disengage the flywheel ring gear. If the solenoid is at fault, (See TESTING - Solenoids , described later in this story).