Volvo Service Manual, Section 3(37) Component Wiring Diagram

From Chassis No. 4854

Contents
 Page 
Air dryer9
Air pressure gauge14
Alternator, charging circuit8
Articulated bus16
  
Battery master switch5, 6
Blinkers11
Brake lights9
Buzzer5
  
Coach connections2
Coolant level10
Coolant temperature13
  
Differential lock7
  
Emergency switch5
Engine compartment fan7
Exhaust brake6
  
Fuel gauge13
Fullbeams and dipped beams13
  
Gear selector, Voith 8519
ZF HP 5009
  
Horn7
  
Indicator lampsSee List of Components, page 18 and pages 14, 15
  
Jackknife warner (see Articulated bus)16
  
Level control7
  
Oil temperature gauge (ZF HP 500)15
  
Parking brake release/re-setting (see Articulated bus)16
Parking lights12
  
RelaysSee List of Components, page 18
Retarder9
Reversing lights10
  
SendersSee List of Components, pages 17, 19
Speedometer5
Splitter gearbox7
Start aid5
Starting heater5
Starting switch, starting circuit5, 6
Stop, engine6
SwitchesSee List of Components, page 17
  
Tachograph5
Tachometer13
  
Warning lampsSee List of Components, page 18 and pages 14, 15
Windscreen wipe/wash10

Page 1


Coach Builders connectors

Symbol  
Conn.point Description Polarity In Outgoing
A 12"1"10 Horn + X
B 12"3"11 Relay, stop lights + X
C 12"1"12 Relay, reversing lights + X
D 12"1"8 Windscreen wiper motor "+" +X 
E 12"1"9 Windscreen wiper motor "2" + X
F 12"1"7 Windscreen wiper motor 1" + X
G 12"1"5 Windscreen washer motor + X
H 12"1"6 Windscreen wiper motor + X
K 12"1"3 Flasher device "+"+X 
L 12"1"4 Flasher device "left" + X
M 12"1"2 Flasher device "right" + X
N 12"3"6 Ind. lamp "rear view mirror" +X 
O 12"1"1 Indicator lamp "flasher device" +X 
P 12"3"7 Indicator lamp "STOP" +X 
R 12"3"5 Fullbeams and dipped beams +X 
S 6"2"4 Dipped beams, Pmax = 120 W + X
T 6"2"3 Dipped beams, Pmax = 120 W + X
U 6"2"2 Fullbeams, Pmax = 95 W + X
W 6"2"1 Fullbeams, Pmax = 95 W + X
X  32B1 + across relays 306 and 307 + X
Y 6"2"5 Parking light, Pmax = = 120 W + X
Z 6"2"6 Parking light, Pmax = 120W + X
AA 12"3"3 Parking lights +X 
AB 12"3"10 Indicator lamp "Open Door" -X 
AC 12"3"8 Indicator lamp "Lids" -X 
AD  20M24 Indicator lamp (not connected) -X 
AE 12"3"9 Indicator lamp "Door Brake" -X 
BA 150"75"  Starting switch, Pmax = 140 W+ + X

Symbol
Symbol, Relay (operating magnet)Relay (operating magnet)
Symbol, Operating magnet with hold-in winding)Operating magnet with hold-in winding)
Symbol, Closing contactClosing contact
Symbol, Break contactBreak contact
Symbol, Switch, manually turned on/offSwitch, manually turned on/off
Symbol, ResistanceResistance
Symbol, FuseFuse
Symbol, Electric MotorElectric Motor
Symbol, Fixed connection pointFixed connection point
Symbol, Removable connectorRemovable connector
Symbol, Slip ringsSlip rings
Symbol, Indicator Lamp with solid lightIndicator Lamp with solid light
Symbol, LampLamp
Symbol, CoilCoil
Symbol, DiodeDiode
Symbol, BuzzerBuzzer
Symbol, Thermal cut-in<br/>Magnetic cut-inThermal cut-in
Magnetic cut-in
Symbol, Switch, manually, pull-push to switch off/onSwitch, manually, pull-push to switch off/on
Symbol, Switch, manual, automatic parkingSwitch, manual, automatic parking
Symbol, Connectors, minirelayConnectors, minirelay
Symbol, Mechanically operated closing contact with automatic parking
Symbol, Time circuit
Symbol, Solenoid valve
Symbol, Electric motor driven fan
Symbol, Electronic unit
Concerning other symbols, see List of Components, Page 17.

Symbol, 100Current path
+Direct connection to battery
B+Connection across battery master switch
T+Connection across starting switch
60"10"Component 60, marked 10
20C6Component No. 20, marked C, connection 6.
703Fixed connection point at Component No. 703
Symbol, Component No. 309. Refer to current path 104

Page 2


How to read a wiring diagram

Fullbeams and dipped beams (chassis-mounted electrical circuits)

Fullbeams circuit

The List of Contents tells us that the circuit diagram for full and dipped beams is to be found on Page 12. Given here on this page is the same circuit diagram in order to make it easier to follow the path of the current.

The diagram has a number of coach builders connector symbols, that is, lettered squares. The coach builders table of connectors on Page 2 shows that the full and dipped beams have coach builder connector symbols R, S, T, U and W. Also shown there is that connector 12 "3" 5 (connector 12 marked 3 terminal 5) should have a + polarity and an input voltage (when the lighting switch is in the fullbeam/dipped beam position). This voltage is conveyed further through 20A 22 (current path 93), 32B 6 to 56 on step relay 325, which, if in the position drawn, transmits voltage to 56a and from there through the coil in relay 306 for fullbeams to earth via 32. Relay 306 cuts in voltage via 53 "2", 34, 32, 32B 7 32B 4, 32B 3, 32B 2 and the relay contact in relay 306 to fuse 60 "8" and further through 32A 2, 20A 28 to 6 "2" 2 or through fuse 60 "9" through 32A 1, 20A 25 to 6 "2" 1. According to the table of coach builders connectors, connectors 6 "2" 2 and 6 "2" 1 are for fullbeams with + polarity and outgoing voltage. Concerning relay 309 and the parking light circuit, see Page 4.

From connector 6 "2" 1 a cable runs to the fullbeams indicator lamp. Also connected to the indicator lamp is a cable with reference to current path 137. Look up Page 15 where the power path 137 shows that the cable goes to component 159 switch, lamp control.

Fullbeam flasher functions when connector 12 "3" 5 is not in circuit (lighting switch off) and switch 101 closes fora moment. Current to activate the full beam relay 306 comes from fuse 60 "3" via the step relay (325) contact 81a-56a.

The coach builders connector symbol "X" 32 B1 has outgoing "+" voltage when the lighting switch is off.

Page 3


Dipped beams, parking light circuit

Switch 101 switches on dipped beams. Activated is the coil in step relay 325, contact 56-56a changes to 56-56b position and remains in its new position, while contact 81a-56a only is in circuit as long as switch 101 is on. The altered position of the contact for 56-56b activates the dipped beams relay 307 and voltage is fed from fuse 53 "2" (current path 100) via the dipped beams relay contact to fuses 60 "6" and 60 "7" and on through 32A 3, 20A 20 to connector 6 "2" 4 and 32A 8, 20A 27 to 6 "2" 3. Squares S and T stand for the dipped beams connector terminals.

The function step relay-switch, fullbeams-dipped beams switch is made clearer on the diagram with a function table. Above the table are arrow symbols which show that the switch is of the type which automatically returns to the rest position. Digit 1 stands for activated switch, 0 for inactivated, "X" stands for activated circuit. Thus with 101 not activated (see left on table) there is contact between 56-56a, with 101 activation, contact between 81a-56a and 56-56b, but when the switch is released there is only contact left between 56-56b. The next time 101 is activated, there is contact again between 81 a-56a, but contact 56-56b shifts and is connected instead via 56-56a. At the next activation of 101, there is contact again between 81a-56a but the other contact in the relay moves back to 56-56b. There are also corresponding tables for the starting switch, retarder brake and windscreen wiper.

The fullbeams-dipped beams switch also switches on the parking light. The control circuit for relay 309 is voltage-fed via connectors 12 "3" 3, 20A 8 and 32B. When relay 309 closes, voltage is fed via connectors 61"2" 5 and 6 "2" 6 via 53 "2", 34, 32 and fuse 60 "4", 320, 20A 33 and fuse 60 "5", 32A 4, 20A 26.

From 20A 26 the instrument panel lighting is also voltage-fed, with two alternative current powers; full power with switch 115 on, reduced power when switch 115 is off and current is forced through resistance 806.

Page 4


Components (power path 1 to 14)
3Connector, 3-unit
6Connector, 6-unit
12Connector, 12-unit
20Connector, 37-unit
30Battery
32Circuit card, electrical centre
53Fuse holder, 3-unit
54Fuse holder, 4-unit
60Fuse holder, 14-unit
85Junction start aid
144Battery master switch
150Starting switch
342Relay, battery master switch
361Relay, operating battery master switch
700Speedometer
701Tachograph
703Tachometer
704Air pressure gauge
853Buzzer

Page 5


Page 6


Components (power path 15 to 40)
4Connector, 4-unit
6Connector, 6-unit
12Connector, 12-unit
20Connector, 20-unit
32Circuit card, electrical centre
33Circuit card, indicator/warning lamps
53Fuse holder, 3-unit
54Fuse holder, 4-unit
60Fuse holder, 14-unit
125Switch, exhaust brake
149Switch, horn
153Switch, preheating
160Switch, stop engine
161Switch, cold-start
175Switch, level control
176Switch, splitter gear
207Closing contact, indicator lamp/diff. lock
223Slip contact, horn
238Slip contact, thermal
251Breaking contact, splitter gear
312Relay, starting switch
316Relay, control magnet, starter motor
333Timer relay, automatic preheating
334Relay, horn
345Relay, start inhibitor
351Relay, cold start
354Relay, start position
383Relay, engine compartment fan
528Indicator lamp, preheating
601Solenoid valve, diff. lock
603Solenoid valve, stop engine
629Solenoid valve, cold start
642Solenoid valve, splitter gear
643Solenoid valve, level elevation
654Starter motor
665Engine compartment fan
704Air pressure gauge
706Thermometer, coolant temp. gauge
707Fuel gauge
800Starting heater
806Resistance
8002Fuse 240A (battery master switch)

Page 7


Page 8


Components (power path 41 to 63)
4Connector, 4-unit
6Connector, 6-unit
12Connector, 12-unit
20Connector, 37-unit
32Circuit card, electrical centre
33Circuit card, indicator/warning lamps
53Fuse block, 3-unit
60Fuse block, 14-unit
151Switch, retarder brake
182Switch, retarder
194Gear selector, Voith 851
196Switch, ZF HP 500
216Closing contact, stop lights
305Relay, reversing lights
308Relay, stop lights
328Charging regulator
331Relay, retarder brake
345Relay, start inhibitor
349Relay, battery charging warning lamp
398Relay, retarder 2 (ZF HP 500)
505Warning lamp, battery charging
526Indicator lamp, retarder brake
655Alternator
660Alternator and charging regulator
703Tachometer
704Pressure gauge, air
706Thermometer, coolant temp. gauge
707Fuel gauge
807Retarder brake control
810Electrically heated air dryer
853Buzzer
908Shunt
950Electric coils, retarder brake
8002Fuse 240A

Page 9


Page 10


Components (power path 64 to 90)
4Connector, 4-unit
6Connector, 6-unit
12Connector, 12-unit
20Connector, 37-unit
32Circuit card, electrical centre
33Circuit card, indicator/warning lamps
53Fuse block, 3-unit
54Fuse block, 4-unit
60Fuse block, 14-unit
119Switch, windscreen wipers
120Switch, windscreen washers
147Switch, direction indicators
159Switch, bulb failure warning lamp
175Switch, level control
194Gear selector, Voith 851
196Gear selector, ZF HP 500
217Closing contact, reversing lights
233Closing contact, warning lamp, coolant
252Closing contact, start inhibitor
253Closing contact, reversing position
305Relay, reversing lights
322Relay, coolant level
330Relay, windscreen wipers (R) (S)
500Indicator lamp, direction indicators
530Indicator lamp, heated rear view mirror
532Indicator lamp, reversing lights
545Indicator lamp, STOP, bus stop
555Warning lamp, coolant level
703Tachometer
704Pressure gauge, air
706Thermometer, coolant temp. gauge
707Fuel gauge
758Speed sender, gearbox

Page 11


Page 12


Components (power path 91 to 112)
4Connector, 4-unit
6Connector, 6-unit
12Connector, 12-unit
20Connector, 37-unit
32Circuit card, electrical centre
33Circuit card, indicator/warning lamps
34Connector
53Fuse block, 3-unit
60Fuse block, 14-unit
101Switch, fullbeams and dipped beams
115Switch, instrument panel light
175Switch, level control
306 Relay, fullbeams
307 Relay, dipped beams
325Step relay, fullbeams and dipped beams
504Indicator lamp, fullbeams
554Warning lamp, coolant temp.
654Starter motor
703Tachometer
704Pressure gauge, air
706Thermometer, coolant temp. gauge
707Fuel gauge
753Speed sender, engine
756Temperature sender, coolant
757Fuel level sender
806Resistance

Page 13



Page 14


Components (power path 113 to 139, warning/indicator lamps, see below)
4Connector, 4-unit
6Connector, 6-unit
12Connector, 12-unit
20Connector, 37-unit
32Circuit card, electrical centre
33Circuit card, indicator/warning lamps
60Fuse block, 14-unit
159Switch, bulb failure warning lamp
182Switch, retarder
200Break contact, warning lamp, parking brake
202Break contact, warning lamp, oil pressure
248Closing contact engine compartment temp
397Relay, retarder 1 (ZF HP 500)
398Relay, retarder 2 (ZF HP 500)
654Starter motor
703Tachometer
704Pressure gauge, air
706Thermometer, coolant temp. gauge
707Fuel gauge
712Temp. gauge (ZF HP 500)
762Oil temp. sender, gearbox
763Level sender, oil
853Buzzer
903Diode

LampCurrent
path
 LampCurrent
path
500Indicator lamp, direction indicators82 540Warning lamp, oil level125
503Warning lamp, oil pressure, engine129 541Warning lamp, gearbox temp.131
504Indicator lamp, fullbeams99 542Warning lamp, door brake127
505Warning lamp, battery charging47 543Warning lamp, lids, luggage and engine compartments119
507Warning lamp, service brakes117 544Warning lamp, engine compartment temp.113
508Warning lamp, parking brake121 545Indicator lamp, STOP, bus stop84
512Warningr lamp, tyre puncture warner123 546Warning lamp, opening doors115
526Indicator lamp, retarder brake59 547Central warning lamp136
528Indicator lamp, starting heater23 554Warning lamp, coolant temp.110
532Indicator lamp, reversing lights65 555Warning lamp, coolant level77

Page 15


Articulated bus
Components (current path 121 to 124, 64, 64, 200 to 206)
2Connector, 2-unit
4Connector, 4-unit
6Connector, 6-unit
8Connector, 8-unit
9Connector, 9-unit
12Connector, 12-unit
20Connector, 37-unit
32Circuit card, electrical centre
33Circuit card, indicator/warning lamps
53Fuse block, 3-unit
54Fuse block, 4-unit
60Fuse block, 14-unit
181Switch, re-set parking brake
217Closing contact, reversing lights
221Closing contact, jackknifing warner
256Closing contact, parking brake
260Closing contact, tyre puncture warner
392Relay, jackknifing warner
393Relay, re-set parking brake
512Warning lamp, tyre puncture warner
558Indicator lamp, jackknifing warner
647Solenoid valve, parking brake
703Tachometer
704Pressure gauge, air
706Thermometer, coolant temp. gauge
707Fuel gauge

Page 16


List of Components

Comp. No.DescriptionPositionCurrent Path
2 Connector, 2-unit
3 Connector, 3-unit "I" steering column -
4 Connector, 4-unit under instrument panel -
6 Connector, 6-unit "D" "G" "H" under dashboard;
"2" coachbuilder's connections under dashboard
-
8 Connector, 8-unit "K" and "L" electrical centre -
9 Connector, 9-unit "N" instrument panel -
12 Connector, 12-unit "1" and "3" coachbuilder's connections under dashboard;
"C" under dashboard
-
20 Connector, 37-unit "A" and "B" under pedal plate,
"G" and "M" in coupling box, battery box
-
30 Batteries Battery box 2
32 Circuit card, electrical centre Depending on coachbuilder -
33 Circuit card, indicator/warning lamps Instrument panel 77, 121, 135, 110
Articulated Bus 121
34 Connection block At steering column/pedal plate under instrument panel -
37 Terminal, earth connection - -
53 Fuse block, 3-unit Battery box, inside junction box -
54 Fuse block, 4-unit Battery box, inside junction box -
60 Fuse block, 14-unit In electrical centre -
85 Start aid, 2-unit Junction box, battery box 3
101Stalk, fullbeams and dipped beams Steering column 91
115Switch, instrument panel light Instrument panel 102
119Stalk, windscreen wipers Steering column 72-77
120Stalk, windscreen washers Steering column 72-77
125Switch, exhaust brake Pedal plate 29
126Switch, diff. lock, wheels, rear Instrument panel 34
144Switch, battery master switch Junction box, battery box 2
147Stalk, direction indicators Steering column 78-79
149Switch, horn Steering wheel hub 32
150Switch, starting switch Steering column 12
151Switch, retarder brake Instrument panel 55-57
153Switch, automatic preheating Instrument panel 25
159Switch, bulb failure warning Instrument panel 86, 137
160Switch, stop engine Instrument panel 28
161Switch, cold start Instrument panel 17
175Switch, level control Instrument panel 40
176Switch, splitter gear Gear lever 36
181Switch, re-set parking brake Instrument panel 203
182Switch, retarder Instrument panel -
194Gear selector Voith 851 Instrument panel -
196Gear selector ZF HP 500 Instrument panel -
200Break contact, warning lamp, parking brakePedal plate 121
Articulated Bus 121
202Break contact, warning lamp, oil pressure Engine 129
207Closing contact, indicator lamp, diff. lock, wheels, rearRear axle 35
216Closing contact, stop lights Pedal plate 61
217Closing contact, reversing lights Manual gearbox 64
Articulated Bus 64
221Closing contact, jackknifing warning Articulation joint 201
223Slip switch, horn Steering wheel 32
233Closing contact, warning lamp, coolant levelPipe, expansion tank 76
238Closing contact, thermal Engine compartment 31
248Closing contact, engine compartment tempemperatureEngine compartment 113
251Break contact, SPLIT Gearbox 37
252Closing contact, start inhibitor Gear selector -
253Closing contact, reversing position (Allison transmission)Instrument panel (selector lever) 65
Articulated Bus 65
256Closing contact, parking brake operation Articulation joint 201
Articulated Bus 201
260Closing contact, tyre puncture warning Articulated axle 122, 123
Articulated Bus 122, 123

Page 17


List of Components

Comp. No.DescriptionPositionCurrent Path
305Relay, reversing lights Instrument panel 67, 68, 69
306Relay, fullbeams Electrical centre 91, 96
307Relay, dipped beams Electrical centre 93, 94
308Relay, stop lights (3-stage) Instrument panel 62-63
309Relay, parking lights Electrical centre 100, 104
312Relay, starting heater In junction box, battery box 22, 25
316Relay, starter motor solenoid In junction box, battery box 19, 20
322Relay, coolant level Electrical centre 76, 77
325Step relay, fullbeams and dipped beams Electrical centre 91, 92, 93
328Charging regulator In junction box, battery box (115 A gen, in alternator)42-43, 44-45
330Relay, windscreen wipers Stay under instrument panel 70, 71, 73, 75
331Relay, retarder brake In junction box retarder
(frame member in front of retarder)
52-55
333Time relay, automatic pre-heating Electrical centre 26-27
334Relay, horn Electrical centre 32-33
342Battery master switch Junction box, battery box (electrical) 4-5
345Relay, start inhibitor Electrical centre 17, 48
349Relay, charge lamp Electrical centre 46, 47
351Relay, cold start Junction box, battery box 17, 18
354Relay, start position Electrical centre 16, 17
361Relay, battery master switch operation In junction box, battery box 5
383Relay, engine comp. fan In junction box, battery box 30, 31
384Relay, SPLIT Behind instrument panel 36, 37-38
392Relay, jackknifing warning Electrical centre 201, 202
393Relay, parking brake re-set Electrical centre 202, 203
397Relay, retarder 1 ZF HP 500 Instrument panel -
398Relay, retarder 2 ZF HP 500 Instrument panel 62-63
500Indicator lamp, dir. indicator, tractor Lamp panel, green 82
503Warning lamp, oil pressure, engine Lamp panel, yellow 129
504Indicator lamp, fullbeams Lamp panel, blue 99
505Warning lamp, battery charge Lamp panel, yellow 47
507Warning lamp, service brakes Lamp panel, red 117
508Warning lamp, parking brake Lamp panel, red 121
Articulated Bus 121
(512)Indicator lamp, tyre puncture warner Instrument panel 122
Articulated Bus 122
526Indicator lamp, retarder brake Lamp panel, green 59
528Indicator lamp, starting heater Lamp panel, yellow 23
530Indicator lamp, rear view mirror heating Lamp panel, green 80
532Indicator lamp, reversing lights Lamp panel, yellow 65
540Warning lamp, oil level Lamp panel, yellow 125
541Warning lamp, gearbox temperature Lamp panel, yellow 131
542Warning lamp, door brake Lamp panel, red 127
543Warning lamp, lids, luggage and engine compartmentLamp panel, red 119
544Warning lamp, engine compartment temperatureLamp panel, red 113
545Indicator lamp, STOP, bus stop Lamp panel, yellow 84
546Warning lamp, opening doors Lamp panel, red 115
547Central warning for indicator and warning lampsInstrument panel 136
554Warning lamp, coolant temperature Lamp panel, yellow 110
555Warning lamp, coolant level Lamp panel, yellow 77
558Warning lamp, jackknifing warning Instrument panel 206
601Solenoid valve, dill. lock, wheels, rear Air output behind battery box 34
603Solenoid valve, engine stop Air output behind battery box 28
629Magnet, cold start On engine 18
642Solenoid valve, overdrive (split) Air output behind battery box 37, 38
643Solenoid valve, level control Air output behind battery box 40
647Solenoid valve, parking brake operation Crossmember in front of rear axle 202
654Starter motor On motor 20-21
655Alternator 60 A/80 A In front of front axle 41, 44
660Alternator with charging regulator In front of front axle 45
665Engine compompartment fan In engine compartment 30

Page 18


List of Components

Comp. No.DescriptionPositionCurrent Path
700Speedometer On instrument panel 7-9
701Tachograph On instrument panel 7-9
703Tachometer On instrument panel 105
704Pressure gauge, air On instrument panel 117
706Thermometer On instrument panel 108
707Fuel gauge On instrument panel 111
712Temperature gauge, gearbox (ZF HP 500) Instrument panel 133
753Speed sender, engine On engine 106-107
756Temperature gauge sender, coolant On engine 109-110
757Fuel level sender In fuel tank 112
757Speed sender, gearbox On gearbox 87-89
762Oil temperatre sender, gearbox On piping in gearbox 131, 133
763Lever sender, oil In lube oil tank, engine 125
800Starting heater On engine 22
806Resistance Under dashboard (lighting power, at 665) 30, 1103
807Retarder brake controls Hand control dashboard; foot control footbrake valve 51-54
810Heated air dryer In air dryer lower section 49
853Buzzer Under dashboard 137-138
903Diode Under dashboard -
908Shunt In junction box, battery box (80 A alt.) 44
950El. coils retarder brake In retarder brake 52-55
8002Fuse 240A Junction box, battery box 21, 50

Page 19