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© 2012 Delmar, Cengage Learning Starting System Service Chapter 29.

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Presentation on theme: "© 2012 Delmar, Cengage Learning Starting System Service Chapter 29."— Presentation transcript:

1 © 2012 Delmar, Cengage Learning Starting System Service Chapter 29

2 © 2012 Delmar, Cengage Learning Objectives Measure amperage draw on a starting system Measure voltage drops on both the positive and ground sides of the starting circuit Diagnose no-crank conditions with a test light Replace a solenoid and starter drive

3 © 2012 Delmar, Cengage Learning Introduction This chapter deals with the process for testing and repairing starter system problems –Principles of operation and electrical fundamentals in earlier chapters will be important Today, many starters are replaced with new or rebuilt units –Instead of being repaired in the shop –Local labor rates dictate whether a starter can be rebuilt economically by the shop

4 © 2012 Delmar, Cengage Learning Starting System Service Failure diagnosis is important before parts replacement –Most parts stores will not accept returns of electrical items Testing a starter: follow a logical procedure –Do not skip steps Two types of problems: –Mechanical –Electrical

5 © 2012 Delmar, Cengage Learning Starting System Service (cont’d.) Visual check –Check the wiring connections to see they are clean and tight Cable should not get hot during cranking Volt-amp tester –Used to test the starting and charging systems

6 © 2012 Delmar, Cengage Learning Starting System Tests Low battery voltage: biggest cause of starter motor failure –Weak battery: solenoid makes a series of rapid clicks –Starter draws twice the current if battery voltage drops by half During starter tests –Fuel or ignition system must be disabled –Do not crank the engine with the coil to distributor wire simply disconnected

7 © 2012 Delmar, Cengage Learning

8 Cranking Voltage and Amperage Test Using a VAT to check starter motor amp draw –Clamp inductive pickup around the battery cable Cranking test results –Normally, when the voltage drops, the amperage draw goes up –When there is resistance, there is a voltage drop Cranking speed –Generally, 250 engine rpm is the speed for a standard starter

9 © 2012 Delmar, Cengage Learning Circuit Resistance Test Voltage drop testing measures voltage lost when current flows from source to load –No service required if less than 0.6 volt drop More voltage drop requires pinpoint tests –Normal voltage drop: about 0.2 volt –If voltage drop reading is high, check each connection in the circuit

10 © 2012 Delmar, Cengage Learning

11 No-Crank Tests Using a Test Light Engine does not crank –Usually because of an open circuit Use 12-volt test light to see if there is power at the outlet of the solenoid –If no light, work back through the system until you find power Next test is to check the starter’s ground path –If the light comes on, the ground path is good Starter must be the problem

12 © 2012 Delmar, Cengage Learning


14 Solenoid Problems Causes of a rapidly clicking solenoid –Weak battery –Corroded or loose battery cable connection –Open circuit in a hold-in winding Single click when battery is in good condition –Often caused by burned contacts in the solenoid Park neutral position (PNP) switch –Moving shift lever while turning ignition to start will allow engine to crank Start switch should be adjusted

15 © 2012 Delmar, Cengage Learning Solenoid Problems (cont'd.) Manual transmissions have a clutch start switch –Should be no continuity when clutch pedal is up

16 © 2012 Delmar, Cengage Learning Starter Repair Starters may not be economical to rebuild –Depends on: Price of parts Wages Shop work load Many shops replace starter drives and solenoids

17 © 2012 Delmar, Cengage Learning Starter Disassembly Considerations –Mark disassembled parts –Disconnect solenoid’s electrical terminals Remove two screws that hold solenoid on starter –Twist solenoid until locking flange is free –Remove bolts, end frame, and starter body from drive end housing –Remove armature from the housing –Inspect bearings or bushings at both ends of housing

18 © 2012 Delmar, Cengage Learning Starter Drive Service Starter drives often do not last the life of the starter motor –Before replacing the starter drive with a new one, count the teeth on the drive pinion Match old and new to see they are the same –Inspect the starter ring gear for damage Brushes may wear thin and have to be replaced –Replace whenever a starter taken apart

19 © 2012 Delmar, Cengage Learning

20 Starter Reassembly Some starters have brushes on pivots –Others require pulling up on springs that hold brushes against the commutator

21 © 2012 Delmar, Cengage Learning Pinion Clearance Tests Starter on the bench –Solenoid energized –Push pinion back toward armature –Check clearance with feeler gauge Starter on the engine –Check pinion to flywheel ring gear clearance –Excessive clearance Starter can be loud and teeth can be damaged –Too little clearance Starter could bind and amp draw will be higher

22 © 2012 Delmar, Cengage Learning



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