Volvo VNL Service Manual page 40

Group 30 Electrical System—VNL, VNM
Stop/Hazard Lights
•
The stop and hazard lights are powered through
fuse 29 through wire 70, which powers the stop light
switch, located at the driver side cowl in the engine
compartment.
•
From the stop light switch, wire 75 goes to the tractor
stop lamp relay (R6). From wire 75, wire 75A goes to
the ECU brake input relay (R5). Power is sent through
wire 75A to open the circuit on that relay.
•
Relay R5 is grounded by wire 0R-D to the bus bar in
the Truck Electrical Center (TEC).
•
Wire 75 powers relay R6 from the stop lamp switch
and fuse 29. Relay R6 is grounded by wire 0R-L to
the bus bar in the TEC. When R6 is switched ON it
opens the circuit between wires 122 and 71. It also
switches wire 71 to +12V by battery power wire 1-B
through fuse 48 to wire 76 on relay R6.
•
Wire 71 provides power to the turn signal switch,
sending power to wires 115 and 116 for the tractor
tail lamps. The tail lamps are grounded by wire 0M-D
to a stud on the passenger side cowl in the engine
compartment.
•
From wire 75A at relay R5, power continues on wire
75B to the trailer stop lamp relay (R11). Wire 75B
supplies power to the coil on relay R11 to switch the
trailer brake relay on. Relay R11 is battery powered
through 1-D to fuse 20 and onto wire 77 to relay R11.
•
When relay R11 is switched ON , wire 77 powers wire
72 to the trailer stop lights. Relay R11 is grounded by
0R-K, which connects to wire 0R-J to the bus bar in
the TEC.
38
Stop/Hazard Lights With Right Turn
Signal On
•
Wire 113 supplies power to the right front turn light.
Ground is through wire 0H-B to a ground stud on
the passenger side cowl in the engine compartment.
Wire 113 sends a signal to the instrument cluster for
the right turn indicator.
•
Wire 113 also supplies power to the trailer connector
and side repeater. Ground for the side repeater is
0M-A to a passenger side interior ground stud.
•
Wire 112 from the flasher unit feeds the left front
turn light. Ground is through wire 0H to 0H-A to a
passenger side interior ground stud. Wire 112 sends
a signal to the instrument cluster for the left turn
indicator.
•
Wire 112 also supplies power to the trailer connector
and side repeater. These lights will continue to flash
with the hazard lights on.
•
With the right turn switch on, wire 115 will continue
to be powered by the stop light circuit. 115 goes to
the left tail lamp, which is grounded by 0M-D to a
ground stud on the passenger side cowl in the engine
compartment.
•
The right turn signal will still be powered by wire 111
from the hazard switch. So when the right turn switch
is ON, the path from the stop light switch on wire 71 is
broken, and the circuit between wire 111 and 116 is
completed. Wire 116 feeds the right rear turn signal.
•
Ground for the right tail light is on the jumper harness
from the right to left tail light, then from the left tail light
on 0M-D.
•
The left circuit is functionally the same as the right.
For more information, see the vehicle electrical
schematics.
Design and Function