AUT 242 – Auto Electricity II. Chapter 20 Cranking System Diagnosis and Service. OBJECTIVES. After studying Chapter 20, the reader will be able to: Prepare for ASE Electrical/Electronic Systems (A6) certification test content area “C” (Starting System Diagnosis and Repair).
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Cranking System Diagnosis and Service
After studying Chapter 20, the reader will be able to:
Voltage dropKEY TERMS
FIGURE 20–1 A theft deterrent indicator lamp of the dash. A flashing lamp usually indicates a fault in the system, and the engine may not start.STARTING SYSTEM TROUBLESHOOTINGPROCEDURE
FIGURE 20–2 Voltmeter hookups for voltage drop testing of a solenoid-type cranking circuit.VOLTAGE DROP TESTINGTEST PROCEDURE
FIGURE 20–3 Voltmeter hookups for voltage drop testing of a Ford cranking circuit.VOLTAGE DROP TESTINGTEST PROCEDURE
FIGURE 20–4 To test the voltage drop of the battery cable connection, place one voltmeter lead on the battery terminal and the other voltmeter lead on the cable end and crank the engine. The voltmeter will read the difference in voltage between the two leads, which should not exceed 0.20 volt (200 mV).VOLTAGE DROP TESTINGTEST PROCEDURE
FIGURE 20–5 A starter amperage tester uses an amp probe around the positive or negative battery cables.STARTER AMPERAGE TEST
FIGURE 20–6 The starter is located under the intake manifold on this Cadillac Northstar engine.STARTER REMOVALPROCEDURE
FIGURE 20–7 An exploded view of a typical solenoid-operated starter.STARTER MOTOR SERVICE
FIGURE 20–8 GM solenoid ohmmeter check. The reading between 1 and 3 (S terminal and ground) should be 0.4 to 0.6 ohm (hold-in winding). The reading between 1 and 2 (S terminal and M terminal) should be 0.2 to 0.4 ohm (pull-in winding).STARTER MOTOR SERVICE
FIGURE 20–9 Measuring an armature shaft for runout using a dial indicator and V-blocks.STARTER MOTOR SERVICE
FIGURE 20–10 Replacement starter brushes should be installed so the beveled edge matches the rotation of the commutator.STARTER MOTOR SERVICE
FIGURE 20–11 A shim (or half shim) may be needed to provide the proper clearance between the flywheel teeth of the engine and the pinion teeth of the starter.STARTER DRIVE-TO-FLYWHEEL CLEARANCE
1. A growler is used to test what starter component?
2. Two technicians are discussing what could be the cause of slow cranking and excessive current draw. Technician A says that an engine mechanical fault could be the cause. Technician B says that the starter motor could be binding or defective. Which technician is correct?
3. A V-6 is being checked for starter amperage draw. The initial surge current was about 210 amperes and about 160 amperes during cranking. Technician A says the starter is defective and should be replaced because the current flow exceeds 200 amperes. Technician B says this is normal current draw for a starter motor on a V-6 engine. Which technician is correct?
4. What component or circuit can keep the engine from cranking?
5. Technician A says that a discharged battery (lower than normal battery voltage) can cause solenoid clicking. Technician B says that a discharged battery or dirty (corroded) battery cables can cause solenoid clicking. Which technician is correct?
6. Slow cranking by the starter can be caused by all except ________ .
7. Bench testing of a starter should be done ________ .
8. If the clearance between the starter pinion and the engine flywheel is too great, ________.
9. A technician connects one lead of a digital voltmeter to the positive (+) terminal of the battery and the other meter lead to the battery terminal (B) of the starter solenoid and then cranks the engine. During cranking, the voltmeter displays a reading of 878 mV. Technician A says that this reading indicates that the positive battery cable has too high resistance. Technician B says that this reading indicates that the starter is defective. Which technician is correct?
10. A vehicle equipped with a V-8 engine does not crank fast enough to start. Technician A says the battery could be discharged or defective. Technician B says that the negative cable is loose at the battery. Which technician is correct?