501
Chapter 5 PartC:
Preheating system - diesel models
Contents
Glow plugs - removal, inspection and refitting 2 Preheating system - description and testing 1 Preheating system control unit - removal and refitting 3
Degrees of difficulty
Ea3y, suitable
for &
novice with little
|| experience ^
Fairty easy,
suitable for beginner with
some experience
jQ
Fairty diffctit, ^
suitable
for competent
DIY
mechanic
Difficult, suitable for
experienced DIY JR mechanic ^
Very difficult, ^ suitable fbrexpertDfY JR or professional ^
Specifications
Torque wrench setting Nm ibf ft Heater glow plugs 15 11
1 Preheating system -description and testing
Description 1 Each swirl chamber has a heater plug (commonly called a glow plug) screwed into it. The plugs are electrically-operated before and during start-up when the engine is cold. 2 Electrical feed to the glow plugs Is controlled by a relay/timer unit. The coolant temperature determines the period of heating that takes place. 3 A warning light in the instnjment panel tells the driver that preheating is taking place. When the light goes out, the engine is ready to be started. The voltags supply to the glow plugs continues for several seconds after the light goes out, If no attempt is made to start, the timer then cuts off the supply, In order to avoid draining the battery and overheating the glow plugs.
Testing 4 If the system malfunctions, testing is ultimately by substitution of known good units, but some preliminary checks may be made as follows. 5 Connect a voltmeter or 12-volt test lamp between the glow plug supply cable and earth (engine or vehicle metal). Make sure that the live connection is kept clear of the engine and bodywork. 6 Have an assistant switch on the ignition, and check that vottage is applied to the glow plugs. Note the time for which the warning light Is lit. and the total time for which voltage Is applied before the system cuts out. Switch off the ignition. 7 At an under-bonnet temperature of 20°C. typical times noted should be 5 or 6 seconds for warning light operation, followed by a further 10 seconds supply after the light goes out. Warning light time will increase with lower temperatures and decrease with higher temp-eratures.
8 If there Is no supply at all, the relay or associated winng is at fault. 9 To locate a defective glow plug, disconnect the main supply cable and the interconnecting strap from the top of the glow plugs. Be careful not to drop the nuts and washers. 10 Use a continuity tester, or a 12-voH test lamp connected to the battery positive terminal, to check for continuity between each glow plug terminal and earth. The resistance of a glow plug in good condition is very low (less than 1 ohm), so if the test lamp does not light or the continuity tester shows a high resistance, the glow plug is certainly defective. 11 If an ammeter is available, the current draw of each glow plug can be checked. After an initial surge of 15 to 20 amps, each plug should draw approximately 12 amps. Any plug which draws much more or less than this is probably defective. 12 As a final check, the glow plugs can be removed and Inspected as described in the following Section.
Automatic transmission 7B*3
11 When reverse gear Is selected, the control unit keeps the transmission In tow ratio, if this were not the case, it would, In theory, be possible to drive as fast In reverse as in forward gear. 12 An electronic control unit supplies the current to energise the clutch. The control unit receives signals concerning engine speed, road speed, accelerator pedal position, and gear selector position, Sensors include the following. a) Engine rpm sensor (from the Injection/ignition control unit) b) Accelerator pedal switch
c) Throttle valve position sensor d) Selector lever position sensor e) Vehicle speed sensor f) Coolant temperature sensor g) Air conditioning sensor h) Brake switch I) Torque signal
13 The final drive/differential unit Is conventional. Drive from the driven pulley is transmitted to the differential by an Intermediate reduction gear. 14 The ECVT incorporates a warning light which illuminates when a fault occurs.
Precautions 1$ Observe the following precautions to avoid damage to the automatic transmission: a) Do not attempt to start the engine by pushing or towing the car. b) If the car has to be towed for recovery, the distance must not exceed 12 miles (20
km),
and the speed must not exceed
19
mph
(30 kph).
If these conditions cannot be met, or If transmission damage is suspected, only tow the car with the front wheels clear of the ground. c) Only engage P or R when the vehicle is stationary.
1.1b Electromagnetic f Coil 2 Signal from vehicle speed sensor 3 Transmission 4 Electromagnetic powder 5 Drive shaft (driven by crankshaft) $ Transmission input shaft 7 Electromagnetic clutch housing 8 ECVT control unit
clutch control system 9 Accelerator pedal micro switch 10 Throttle
vafve
opening position potentiometer 11 Multifunction switch 12 Ignition switch
13
Air conditioning
signal
14 Engine PPM
signal
15 Accelerator pedal 16 Coolant temperature signal 17 Injection/ignition control unit 18 8attery
1.1c Hydraulic control system 3 Injection/ignition control unit 4 Air conditioner sensor
signal
6 Coolant temperature signal 7 Clutch signal 8 Engine RPM
signal
9 ECVT warning light 10 Selector lever position 11 Accelerator
pedal
switch/throttle
valve
potentiometer/torque signal 12 Brake switch 13
ECVT
control unit 14 Signal from vehicle speed sensor
15
Accelerator pedal position switch
16 Pulley ratio 17 Input shaft RPM 18 Primary oil pressure
19
Primary pulley 20 Electromagnetic clutch 21 Pressure regulating solenoid valve 22 Oil pressure control valve 23 Secondary oil pressure 24 Slip ring 25 Drive from engine 26 Oil pump 27 Vehicle speed sensor 28 Secondary pulley 29 Belt and pulley 30 Drive to drlveshafts
