S&T Series Blazer, Bravada, Envoy, Jimmy, Rainier, Trailblazer, Xtreme

Testing

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Before removing the starter for repair or replacement, check the condition of all circuit wiring for damage. Inspect all connection to the starter motor, solenoid, ignition switch, and battery, including all ground connections. Clean and tighten all connections as required.

Check all switches to determine their condition. Vehicles equipped with manual transmission have a clutch safety switch attached to the clutch pedal bracket which closes when the clutch is depressed. Vehicles equipped with automatic transmissions have a manual interlock in the steering column which does not allow the ignition switch to turn to the start position unless the transmission is in the Park or Neutral position.

Check the battery to ensure that it is fully charged. For more information on battery service, please refer to Section 1 of this manual.

Check the battery cables for excessive resistance as follows:


CAUTION
To prevent possible injury from a moving vehicle or operating engine, engage the parking brakes, block the drive wheels, place the manual transmission in Neutral or the automatic transmission in Park, and disconnect the battery feed at the distributor before performing these tests.



Check the voltage drop between the negative battery terminal and the vehicle frame by placing one lead of a voltmeter on the grounded battery post (not the cable clamp) and the other lead on the frame. Turn the ignition key to the START position and note the voltage drop.
 
Check the voltage drop between the positive battery terminal (not the cable clamp) and the starter terminal stud. Turn the ignition key to the START position and note the voltage drop.
 
Check the voltage drop between the starter housing and the frame. Turn the ignition key to the START position and note the voltage drop.
 
If the voltage drop in any of the above is more than 1 volt, there is excessive resistance in the circuit. Clean and retest all cables not within specification. Replace as necessary.
 

No Load Test



Make the test connections as shown in the illustration. Close the switch and compare the rpm, current and voltage readings with the accompanying specification illustration.



Current draw and no load speed within specifications indicates normal condition of the starter motor.
 
Low free speed and high current draw indicates worn bearings, a bent armature shaft, a shorted armature or grounded armature fields
 
Failure to operate with high current draw indicates a direct ground in the terminal or fields, or frozen bearings.
 
Failure to operate with no current draw indicates an open field circuit, open armature coils, broken brush springs, worn brushes or other causes which would prevent good contact between the commutator and the brushes.
 
A low no load speed and low current draw indicates high internal resistance due to poor connections, defective leads or a dirty commutator.
 
High free speed and high current draw usually indicate shorted fields or a shorted armature.

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Fig. Proper connections for the starter no-load test



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Fig. Starter no load test specifications-28-MT series



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Fig. Starter no load test specifications-SD series

 

 
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