Starting System: Description and Operation
OVERVIEWThe battery, starting, and charging systems operate with one another, and must be tested as a complete system. In order for the vehicle to start and charge properly, all of the components involved in these systems must perform within specifications.
However, when attempting to diagnose any of these systems, it is important that you keep their interdependency in mind.
The diagnostic procedures used include the most basic conventional diagnostic methods to the more sophisticated On-Board Diagnostics (OBD) built into the Powertrain Control Module (PCM). Use of a induction milliampere ammeter, volt/ ohmmeter, battery charger, carbon pile rheostat (load tester), and 12-Volt test lamp may be required.
All OBD-sensed systems are monitored by the PCM. Each monitored circuit is assigned a Diagnostic Trouble Code (DTC). The PCM will store a DTC in electronic memory for any failure it detects. See the On-Board Diagnostics Test in Charging System for more information.
INTRODUCTION
The starting system consists of:
- Battery
- Starter relay
- Starter with an integral solenoid
- Ignition switch
- Clutch pedal position switch (manual transmission)
- Park/neutral position switch (automatic transmission)
- Wiring harness and connections.
This covers diagnosis of the complete starting system, except the battery. However, this only covers service procedures for the starter and starter relay. Service procedures for other starting system components can be located as follows:
- Battery - refer to Battery for the diagnostic and service procedures
- Ignition switch - refer to Ignition Systems for the service procedures
- Clutch pedal position switch - refer to Clutch for the service procedures
- Park/neutral position switch - refer to Transmission for the service procedures
- Wiring harness and connections
NOTE: This covers both Left-Hand Drive (LHD) and Right-Hand Drive (RHD) versions of this model. Whenever required and feasible, the RHD versions of affected vehicle components have been constructed as mirror-image of the LHD versions. While most of the illustrations used represent only the LHD version, the diagnostic and service procedures outlined can generally be applied to either version. Exceptions to this rule have been clearly identified as LHD or RHD, if a special illustration or procedure is required.
SYSTEM OPERATION
The starting system components form two separate circuits. A high-amperage feed circuit that feeds the starter between 150 and 350 amperes, and a low-amperage control circuit that operates on less than 20 amperes.
If the vehicle is equipped with an automatic transmission, battery voltage is supplied through the low- amperage control circuit to the coil battery terminal of the starter relay when the ignition switch is turned to the Start position. The park/neutral position switch is installed in series between the starter relay coil ground terminal and ground. This normally open switch prevents the starter relay from being energized unless the automatic transmission gear selector is in the Neutral or Park positions.
If the vehicle is equipped with a manual transmission, it has a clutch pedal position switch installed in series between the ignition switch and the coil battery terminal of the starter relay. This normally open switch prevents the starter relay from being energized unless the clutch pedal is depressed. The starter relay coil ground terminal is always grounded on vehicles with a manual transmission.
When the starter relay coil is energized, the normally open relay contacts close. The relay contacts connect the relay common feed terminal to the relay normally open terminal. The closed relay contacts energize the starter solenoid coil windings.
The energized solenoid pull-in coil pulls in the solenoid plunger. The solenoid plunger pulls the shift lever in the starter. This engages the starter overrunning clutch and pinion gear with the starter ring gear on the automatic transmission torque converter drive plate, or the manual transmission flywheel.
As the solenoid plunger reaches the end of its travel, the solenoid contact disc completes the high- amperage starter feed circuit and energizes the solenoid plunger hold-in coil. Current now flows between the solenoid battery terminal and the starter motor, energizing the starter.
Once the engine starts, the overrunning clutch protects the starter from damage by allowing the starter pinion gear to spin faster than the pinion shaft. When the driver releases the ignition switch to the On position, the starter relay coil is de-energized. This causes the relay contacts to open. When the relay contacts open, the starter solenoid plunger hold-in coil is de-energized.
When the solenoid plunger hold-in coil is de-energized, the solenoid plunger return spring returns the plunger to its relaxed position. This causes the contact disc to open the starter feed circuit, and the shift lever to disengage the over running clutch and pinion gear from the starter ring gear
Starter
The starter motor incorporates several features to create a reliable, efficient, compact and lightweight unit. A planetary gear system (intermediate transmission) is used between the electric motor and the pinion gear This feature makes it possible to reduce the dimensions of the starter. At the same time, it allows higher armature rotational speed and delivers increased torque through the pinion gear to the starter ring gear on the automatic transmission torque converter or torque converter drive plate.
The use of a permanent magnet field also reduces the size and weight of the starter. The permanent magnet field consists of four high-strength permanent magnets. The magnets are aligned according to their polarity, and are permanently mounted in the starter field frame.
The starter motors for all engines are activated by a solenoid mounted to the overrunning clutch housing. However, the starter motor and solenoid are serviced only as a complete assembly.If either component fails, the entire assembly must be replaced.
CAUTION:
- Permanent magnet starters are highly sensitive to hammering, shocks, and external pressure. The permanent magnets may be damaged and the starter rendered unserviceable, if subjected to any of these conditions.
- The starter motor must not be clamped in a vise by the starter field frame. Doing so may damage the permanent magnets. The starter should only be clamped by the mounting flange.
- Do not connect the starter motor incorrectly when testing. Reverse polarity may damage the permanent magnets and render the starter unserviceable.
Starter Relay
The starter relay is a International Standards Organization (ISO)-type relay The starter relay is a electro-mechanical device that switches current to the pull-in coil of the starter solenoid, when the ignition switch is turned to the Start position.
The starter relay is located in the Power Distribution Center (PDC) in the engine compartment. Refer to the PDC label for relay identification and location.
CIRCUIT OPERATION
With Automatic Transmission
Circuit A0 from the battery splices to the engine starter motor and the Power Distribution Center (PDC).
Fuse 2 in the PDC supplies battery voltage to the contact side of the engine starter motor relay on circuit A2. When the coil side of the engine starter motor relay energizes, the contacts close and connect circuit A2 to circuit T40. Circuit T40 supplies battery voltage to the starter motor solenoid.
When the ignition switch is in the START position it connects circuit A2 to circuit A41. Circuit A41 connects to circuit T141 through a jumper wire. Circuit T141 supplies battery voltage to the coil side of the starter motor relay. When the PARK/NEUTRAL position switch closes, it supplies ground for the coil side of the starter motor relay. Circuit T41 connects the coil side of the relay to the PARK/NEUTRAL position switch.
When the starter motor relay energizes and its contacts close, circuit T40 supplies battery voltage to the starter motor solenoid. Circuit A0 from the battery supplies voltage to the starter motor when the solenoid energizes.
With Manual Transmission
Circuit A0 from the battery splices to the engine starter motor and the Power Distribution Center (PDC).
Fuse 2 in the PDC supplies battery voltage to the contact side of the engine starter motor relay on circuit A2. When the coil side of the engine starter motor relay energizes, the contacts close and connect circuit A2 to circuit T40. Circuit T40 supplies battery voltage to the starter motor solenoid.
When the ignition switch is in the START position it connects circuit A2 to circuit A41. Circuit A41 connects to circuit T141 through the clutch interlock switch. Circuit T141 supplies battery voltage to the coil side of the starter motor relay. Circuit T41 from the relay coil connects to circuit Z1 through the manual transmission jumper. Circuit Z1 provides ground for the coil side of the relay
When the starter motor relay energizes and its contacts close, circuit T40 supplies battery voltage to the starter motor solenoid. Circuit A0 from the battery supplies voltage to the starter motor when the solenoid energizes.