Section 4 The Starting System - Autoshop 101

1 Electrical Circuit Diagnosis - Course 6234-1 StarterThe starter motor drivesthe engine through apinion gear that engagesthe ring gear onthe 4-01TL623f401cThe Starting System : Uses a powerful electric motor to drive the engine at about 200 RPM (fast enough to allow the fuel and ignition systems to operate). Drives the engine through a pinion gear engaged with a ring gearon the flywheel. Disengages as soon as the engine 4 The Starting SystemStarting SystemOverviewSection 44-2 TOYOTA Technical TrainingThese components make up a typical Toyota Starting System : Starter motor Magnetic switch Over-running clutch Ignition switch contacts Park/neutral position (A/T) or clutch start (M/T) switch Clutch start cancel switch (on some models) Starter relayStarting SystemComponents -AutomaticTransmissionThese components makeup a typical startingsystem (automatictransmission).

2 Fig. 4-02TL623f402 Starting SystemComponentsThe Starting SystemElectrical Circuit Diagnosis - Course 6234-3 Starting SystemComponents -ManualTransmissionThese components makeup a typical startingsystem (manualtransmission).Fig. 4-03L623f403 Section 44-4 TOYOTA Technical TrainingToyota vehicles are fitted with one of two types of starter motors: gear reduction Planetary reduction Segment (PS)Starter MotorThe gear reduction starter is a compactlightweight unit with high torque 4-04TL623f404cThe gear - reduction starter motor contains the components shown. Thistype of starter has a compact, high-speed motor and a set of reduction the motor is smaller and weighs less than conventional startingmotors, it operates at higher speed. The reduction gears transfer this torqueto the pinion gear at 1/4 to 1/3 the motor speed.

3 The pinion gear still rotatefaster than the gear on a conventional starter and with much greater torque(cranking power).Starter MotorGear-ReductionStarter MotorThe Starting SystemElectrical Circuit Diagnosis - Course 6234-5 The reduction gear is mounted on the same shaft as the pinion the conventional starter, the magnetic switch plunger actsdirectly on the pinion gear (not through a drive lever) to push the gearinto mesh with the ring type of starter was first used on the 1973 Corona MKII with the4M, six cylinder engine. It is now used on most 1975 and newerToyotas. Ratings range from KW on most Tercels and some oldermodels to as high as KW on the diesel Corolla, Camry and cold-weather package calls for a KW or KW starter, while KW starter is common on other gear - reduction starter is the replacement starter for mostconventional 44-6 TOYOTA Technical TrainingOlder Toyota models use conventional type starters.

4 This type of starterdrives the pinion gear directly. The pinion gear turns at the same speedas the motor shaft. These starters are heavier and draw more currentthan gear reduction and PS type Starter MotorConventional type starter motors drivethe pinion 4-05TL623f405cNOTEThe Starting SystemElectrical Circuit Diagnosis - Course 6234-7 Both conventional and gear reduction starter motors are fitted with aone-way, over-running clutch. The clutch prevents damage to thestarter when the engine Operation:1. During engine start, the starter pinion gear drives the engine'sflywheel ring Once the engine fires, the ring gear almost instantly begins to turnfaster than the starter pinion gear . Over-speeding would damagethe starter motor if it were not immediately disengaged from thepinion The clutch uses its wedged rollers and springs to disengage thepinion shaft from the clutch housing (which turns with the motorarmature).

5 This happens any time the pinion shaft tries to turnfaster than the clutch StartingThe clutch housing,armature, and pinion gearturn 4-06TL623f406cOver-runningClutchSection 44-8 TOYOTA Technical TrainingEngine StartedThe clutch housing and the armature turntogether. The ring gear drives the piniongear. The pinion shaft is disengagedfrom the clutch 4-07TL623f407cThe Starting SystemElectrical Circuit Diagnosis - Course 6234-9 The ignition switch incorporates contacts to provide B+ to the relay energizes the starter magnetic switch when the driver turnsthe ignition key to the START SwitchWith key to START position, B+ is applied tothe starter 4-08TL623f408cIgnition SwitchSection 44-10 TOYOTA Technical TrainingThe park/neutral position switch prevents operation of the startermotor unless the shift lever is in Park or Neutral.

6 The switch contactsare in series with the starter control SwitchThe switch closes withthe shift lever in Parkor 4-09TL623f409cPark/NeutralPosition Switch(AutomaticTransmission)The Starting SystemElectrical Circuit Diagnosis - Course 6234-11 For manual transmissions the clutch start switch performs the samefunction as the park/neutral position switch. The clutch start switchopens the starter control circuit unless the clutch is StartSwitchThe switch closes whenthe clutch pedal 4-10L623f410cClutch StartSwitch (ManualTransmission) Section 44-12 TOYOTA Technical TrainingIn some off-road situations it is advantageous to start a manualtransmission vehicle while in gear with the clutch engaged. The driver-controlled safety cancel switch allows the driver to bypass the clutchstart switch to make this possible.

7 This feature is only available onsome StartCancel SwitchThis switch lets thedriver bypass the clutchstart switch for 4-11T623f411cClutch StartCancel SwitchThe Starting SystemElectrical Circuit Diagnosis - Course 6234-13 Ignition switch in ST:1. Current travels from the battery through terminal 50" to thehold-in and pull-in coils. Then, from the pull-in coil, currentcontinues through terminal C" to the field coils and armature Voltage drop across the pull-in coil limits the current to the motor ,keeping its speed The magnetic switch plunger pushes the pinion gear to mesh withthe ring The screw spline and low motor speed help the gears mesh Switch to STThe plunger pulls the drive lever, whichmoves the pinion gear into engagementwith the ring 4-12TL623f412 gear -ReductionStarter OperationSection 44-14 TOYOTA Technical TrainingPinion and ring gears engaged:1.

8 When the gears are meshed, the contact plate on the plunger turnson the main switch by closing the connection between terminals 30" and C."2. More current goes to the motor and it rotates with greater Current no longer flows in the pull-in coil. The plunger is held inposition by the hold-in coil's magnetic Switch to ST (Cont.)The magnetic switch closes and currentfrom the battery drives the startermotor 4-13TL623f413cThe Starting SystemElectrical Circuit Diagnosis - Course 6234-15 Ignition switch in ON:1. Current no longer present at terminal 50," but the main switchremains closed to allow current from terminal C" through thepull-in coil to the hold-in The magnetic fields in the two coils cancel each other, and theplunger is pulled back by the return The high current to the motor is cut off and the pinion geardisengages from the ring The armature has less inertia than the one in a conventionalstarter.

9 Friction stops it, so a brake is not Switch ONCurrent through the starter relay pinion gear disengages from the ringgear, and the magnetic switch 4-14TL623f414cSection 44-16 TOYOTA Technical TrainingAll current Toyota models are fitted with Planetary reduction SegmentConductor (PS) reduction allows the starter motor to operate at a higherspeed than a conventional starter. The reduction gear set reduces the pinion gear speed compared tomotor shaft speed. Higher motor speed yields greater conductor type starters incorporate several designimprovements: More compact Lighter weight Greater output torquePS Starter- OverviewAll current Toyota modelsare fitted with PS 4-15TL623f415PS Starter Motors- OverviewThe Starting SystemElectrical Circuit Diagnosis - Course 6234-17PS Starter- ConstructionCoil wires in PS typestarters are square incross- Section for morecompact winding andgreater output 4-16TL623f416 Section 44-18 TOYOTA Technical TrainingArmature coil wires - The coil wires in a PS starter armature aresquare in cross- Section .

10 More compact winding than round cross- Section wires Greater output torqueSurface commutator - The square shape of the armature conductorsallow the surface of the armature to act as a coils - Conventional starters use field coils. PS type starters usetwo types of permanent magnets instead: Main magnets Inter-polar magnetsThe two types of magnets are arranged alternately inside the yoke. Work together to increase magnetic flux Allows shorter yokePS Starter - ConstructionPS type starters use two types ofpermanent magnets instead offield 4-17TL623f415PS Starter Motors- ConstructionThe Starting SystemElectrical Circuit Diagnosis - Course 6234-19 With the ignition switch placed to the START position:1. Current travels from the battery through the closed ST1 contacts ofthe Ignition Switch and the Park/Neutral Switch, through the coilof the ST Relay to The ST Relay contacts Switchto STARTC urrent from IgnitionSwitch ST1 contactsenergizes the STRelay 4-18TL623f418cPS StarterOperationSection 44-20 TOYOTA Technical Training3.