Wiring and Circuit Protection (18.01)
Electric Distribution/Electronic Control (18.00)
May 2007 Workshop Manual 18-1-7
The terminals in a connector housing can have a special
coating on them. This coating if required is selected using
the following criteria.
• A specific coating requested by component / system owner.
Or
• The current passing through the terminal.
• The environment the connector is to be situated with respect to temperature.
• The open circuit voltage passing through the terminal at a given.
Depending on the above criteria the coating, if required, can
either be gold, silver, phosphor bronze. Generally tin is the
common plating on the terminals but there are some that are
gold. These are identified in the circuits with the letter ‘ G’
which stands for gold afte r the connector number. An
example of this is shown below.
Splices
A s p l ic e is u s e d w h e re m o r e t h a n 2 w i re s t h a t h a v e t h e s a m e
requirement i.e. they need the same signal and meet in the
same harness. In the example below the Front Position
Lamp-LH and Front Side marker-LH require the same
output signal from the CEM. Therefore the 2 wires for the
lamps are spliced into the output wire from the CEM on the
Forward Harness.
Tracing Spliced Wires
Some splices appear on pages as a wire that goes to one spot
and seems to terminate in space. An example of this is
shown below.
Splice Origin Page
(e.g.P9)
Other Page(s) on which the splice occurs .
A separate page is attached containing a list of splice
abbreviations and the harness to which they refer.
G
Gold plated pin
SPL1 FLL FOR
Splice No.
Associated name
Harness that the splice is on
Wiring and Circuit Protection (18.01)
Electric Distribution/E lectronic Control (18.00)
18-1-8 Workshop Manual May 2007
Relays
Another significant component in the circuits is a relay, this
is in simple terms a switch that operates on the principal of
electromagnetism. Below is the circuit symbol for a typical
relay. The relay shown below is a normally open relay in its
inoperative state i.e The arm is in the open position.
Relays can have either 4 or 5 terminals on the base. The
circuit of the relay is shown on the base or the side of the
housing. There are 2 types of numbering convention for the
relay terminals, both of which are shown below.
Below is a circuit diagram to show the function and
operation of a relay in a simple circuit.
The current from a battery for example flows through the
wires to the high power normally open switch (The arm
between pins 30 & 87A) and the low power coil (The box
between pins 85 & 86). As you can see in the example above
the lamp is in not illuminated, because the switch is open.
For the relay to operate there needs to be current flow
through the low power coil i.e Current in to the coil then
through to an earth. The current passes through the relay coil
and creates a magnetic field, this magnetic field is strong
enough to ‘grab’ the high power normally open switch.
The magnetic field pulls the switch from it’s normally open
contact to a normally closed contact. The normally closed
contact has a path to an earth, in this case it goes through a
lamp. The high power current then flows through the high power
normally open switch through the lamp and then to an earth.
This can be seen more clearly in the diagram below.Lamp
Illuminates
Busbars
A busbar is where a electrical
supply is fed into a conductive
bar, wire or pcb track and various modules or components
‘tap’ into this busbar to draw their required power. The
Central Electronic Module has 4 of these busbars internally,
each of which is supplied from an external power supply,
that supply can be a battery feed, ignition feed or a switched
supply.
The symbol shown below is the symbol used on the circuits
for a busbar, the number inside the box refers to the busbar
number in the Central Electronic Module.
Fuses
A fuse is a device used to protect a module or component
from excessive electrical current which can cause damage or
destroy that module or component. In practice the fuse is
placed in between the power source and the module or
component that is being protected.
The size or ‘Rating’ of the fuse in amps is calculated
according to the power requirements of the module or
component it is protecting with other factors being taken
into consideration. If the rating has been calculated correctly
then the fuse will ‘blow’ when excessive current passes
through it before any harm or permanent damage occurs to
the module or component it is protecting.
Wiring and Circuit Protection (18.01)
Electric Distribution/Electronic Control (18.00)
May 2007 Workshop Manual 18-1-9
In a correctly protected circuit, the fuse is placed ‘ Inline’
between the power source in this case the battery and the
lamp. If the lamp goes ‘short circuit’, a massive current will
begin to flow and the fuse will fail causing an open circuit.
The battery and wiring are protected from over current
damage.
Below is the fuse symbol as shown on the circuit diagrams.
The number above the fuse symbol is the fuse number;
allocated to this fuse. The number below the fuse symbol is
the rating.
Resistors
A resistor is an electronic component that by way of its
construction reduces the current flowing through it. A
resistors unit of measure is the Ohm.
The diagrams below show a resi stor and a variable resistor.
Variable Resistors
A variable resistor works in the same manner as a normal
resistor but the resistance values can fluctuate. The
construction of a variable resi stor depends upon its use and
environment.
One example is for the fuel tank level sensor. The tank full
level is 10 ohms and the tank empty level is 204 ohms, the
resistance will vary between 10 and 204 ohms depending on
how much fuel is in the tank.
Lamps
Below is the symbol for a light bulb, shown below the
symbol is the power of the bulb in watts.
Switches
There are numerous of types of switch, several of examples
are shown below.
Normally Open Switch
2 Position Switch
3 Position Switch
Motors and Pumps
The same symbol is used for a pump or a motor, the
description differentiates between them.
Pump
Wiring and Circuit Protection (18.01)
Electric Distribution/E lectronic Control (18.00)
18-1-10 Workshop Manual May 2007
Motor
Diodes
The simplest way of describing a diode is ‘a non return
valve’. The current will flow through the diode from the
anode to the cathode, due to the construction of it though
current cannot come back. Diodes are used to reduce the
possibilities of ‘back feed’. This is where current comes
through the circuit the wrong way for one reason or another.
Below is the circuit symbol for a diode.
Light Emitting Diode (LED)
The light emitting diode (LED) works on the same principal
as the diode. The main difference is that in the
manufacturing process one of the materials is replaced by
another. This replacement mate rial has certain properties
that when a certain voltage passes through it glows.
Transistor
A transistor in simplistic term s is a switch with no moving
parts. The ‘switching’ is controlled by electronics and
currents etc. rather than a physical switch being operated.
Below is the circuit symbol for it. The example shown below
is one of the most common basic type used called a
‘Bipolar’.
Field Effect Transistor (FET)
A field effect transistor (FET) is, in simplistic
terms, a switch with no moving parts. The
‘switching’ is controlled by electronics and
currents etc. rather than a physical switch
being operated. The main difference
between this and the type of transistor shown above is this
one operates using a magnetic field.
Earth / Ground
For an electrical current to ‘flow’ around a circuit it has to
start from a power source and go to an earth / ground. If
there are any breaks in this circ uit then current will not flow,
this is called an ‘Open circuit’
There are 2 types of earth, Signal Earth and Chassis Earth,
these are referred to sometimes as a Quiet Earth and Noisy
Earth respectively.
Some sensors for example specify a Signal / Quiet Earth.
While components such as pumps and motors can have a
Chassis / Noisy Earth. The reason behind this is that pumps,
motors and the like can generate ‘electrical noise’ by the
way of their operation. Some of this ‘electrical noise can be
transferred through wires, it is this ‘electrical noise’ that can
have an adverse effect on sensor signals and affect the
control readings.
Keeping Signal / Quiet and Chassis / Noisy
earths separate reduces th e effect of ‘electrical
noise’ being transferred from component to
component.
This symbol is a standard symbol for earths.
On the circuit diagrams some earths are shown as eyelets
with the description of Earth-**** next to it, the earths also
comply with the 4 digit C number. An example of this is
shown below.
=Anode Cathode
Anode Cathode
LED Colour
Arrow Symbol
indicating light
emission
Wiring and Circuit Protection (18.01)
Electric Distribution/Electronic Control (18.00)
May 2007 Workshop Manual 18-1-11
Maintenance
Forward Harness-Renew
Removal
1. Disconnect vehicle battery.
2. Remove LH headlamp (see Workshop Manual procedure 17.01.AB Headlamp Assembly - LH -
Renew).
3. Remove RH headlamp (see Workshop Manual procedure 17.01.BB Headlamp Assembly - RH -
Renew).
4. Release grommet from body, feed harness from inside of vehicle.
5. Disconnect multiplugs (x2) LH and RH side repeaters.
6. Disconnect multiplugs (x2) LH and RH pad wear indicators.
7. Disconnect multiplug (x2) LH and RH wheel speed sensors.
8. Disconnect multiplugs (x2) LH and RH air flow meters.
9. Disconnect multiplugs (x2) LH and RH headlamp bulb
monitoring resistors.
10. Remove nuts (x6) securing LH and RH earth leads to body (x6).
11. Remove screws (x4) LH and RH harness plate to body and release harness from plate.
12. Remove screen washer reservoir (see Workshop Manual procedure 01.16.DA Reserv oir and Motor Assembly -
Windshield Wash - Renew).
13. Remove fusebox (see Workshop Manual procedure 18.01.KD Fuse Box - Engine Bay - Renew).
14. Disconnect multiplug (x1) purge valve.
15. Disconnect multiplug (x1) ABS modulator.
16. Disconnect multiplug (x1) load level sensor.
17. Disconnect multiplugs (x4) forward harness to cabin harness.
18. Remove wiper motor and linkage (see Workshop Manual procedure 01.16.BA Linkage Assembly - Wiper
- Renew).
19. Remove cross member fr ont latch mounting (see
Workshop Manual procedure 01.14.BD Latch Assembly
- Hood - Renew).
20. Remove nuts (x2) securing earth leads to body (x2).
21. Disconnect multiplug (x1) heated front windshield.
22. Disconnect multiplug PAS sensor.
23. Disconnect multiplugs (x2) A/C compressor. 24. Disconnect multiplug (x1) horn.
25. Release forward harness to engine harness multiplug
(x1) from inner wing and di sconnect multiplugs (x2).
26. Disconnect multiplug (x2) cooling fans.
27. Disconnect multiplug (x1) ambient air temperature sensor.
28. Disconnect multiplugs (X2) crash sensors.
29. Release harness clips (70) and remove harness.
Installation
1. Layout harness around engine bay, feed harness into cabin area and secure grommet.
2. Secure forward harness clips (x70) to body.
3. Connect multiplug (x2) LH and RH side repeaters.
4. Connect multiplug (x2) LH and RH pad wear indicators.
5. Connect multiplugs (X2) LH and RH wheel speed sensors.
6. Connect multiplugs (x2) LH and RH air flow meters.
7. Connect multiplugs (x2) LH and RH headlamp bulb
monitoring resistors.
8. Position earth leads (x6), install and torque tighten nuts (x6).
9. Secure harness to plates (x2) and install plates to body.
10. Connect multiplug (x1) purge valve.
11. Install washer reservoi r (see Workshop Manual
procedure 01.16.DA Reservoir and Motor Assembly -
Windshield Wash - Renew).
12. Install fuse box (see Workshop Manual procedure 18.01.KD Fuse Box - Engine Bay - Renew).
13. Connect multiplug (x1) ABS connector.
14. Connect multiplug (x1) load level sensor.
15. Disconnect multiplug (x4) forward harness to cabin harness.
16. Connect multiplug (x1) heated front screen.
17. Connect multiplug (x1) PAS sensor.
18. Connect multiplugs (x2) A/C.
19. Connect multiplug (x1) horn
20. Position earth leads (x2), install and torque tighten nuts (x2).
21. Secure forward harness multiplug (x1) to inner wing and connect multiplugs (x2).
22. Connect multiplug (x2) cooling fans.
23. Connect multiplug (x1) am bient air temperature sensor.
24. Connect multiplugs (X2) crash sensors.
25. Install cross member front latch mounting 01.14.BD Latch Assembly - Hood - Renew).
26. Install wiper motor and linkage (see Workshop Manual procedure 01.16.BA Linkage Assembly - Wiper -
Renew).
27. Install LH headlamp (see Workshop Manual procedure
17.01.AB Headlamp Assembly - LH - Renew).
28. Install RH headlamp (see Workshop Manual procedure 17.01.BB Headlamp Assembly - RH - Renew).
29. Connect vehicle battery.
Repair Operation Time (ROT)
Warning
To prevent damage to elec trical components, always
disconnect the vehicle battery when working on the
vehicle's electrical system. The earth lead (- ve) must be disconnected first and reconnected last.
Wiring and Circuit Protection (18.01)
Electric Distribution/E lectronic Control (18.00)
18-1-12 Workshop Manual May 2007
Header Latch Harness-Renew (Roadster
Only)
Removal
1. Remove header assembly (see Workshop Manual
procedure 01.05.BB Panel Assembly - Header - Renew).
2. Release insulation from head er latch motor (see Fig. 1).
3. Cut 2 cable ties securing wiring harness to motor
mounting bracket (see Fig. 2).
4. Disconnect 2 motor multiplugs. 5. Remove 3 P-clip screws secu
ring harness to roof header,
release clips from harness (see Fig. 3).
6. Release 4 Velcro straps securing harness to tension strap (see Fig. 4).
7. Remove 1 of the screws securing harness to roof frame.
8. Mark position of B-post trim.
Repair Operation Time (ROT)
Warning
To prevent damage to electrical components, always
disconnect the vehicle battery when working on the
vehicle's electrical system. Th e earth lead (- ve) must be
disconnected first and reconnected last.
Fig. 1
Fig. 2
Fig. 3
Fig. 4
Wiring and Circuit Protection (18.01)
Electric Distribution/Electronic Control (18.00)
May 2007 Workshop Manual 18-1-13
9. Remove 2 screws securing B- post trim to roof frame,
position trim aside (see Fig. 5).
10. Remove 3 P-clip screws secu ring harness to inside of
roof frame, release clips from harness (see Fig. 6).
11. Lower the rear of the roof and secure. 12. Remove 3 screws securing
harness cover plate to roof
frame and remove (see Fig. 7).
13. Return the roof to halfway po sition and secure (see Fig.
8).
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Wiring and Circuit Protection (18.01)
Electric Distribution/E lectronic Control (18.00)
18-1-14 Workshop Manual May 2007
14. Remove P-clip screw securing harness to roof mounting
bracket, release clip from harness (see Fig. 9).
15. Disconnect header latch harness multiplug (see Fig. 10).
16. Remove header latch harness.
Installation
1. Route header latch harness and connect to vehicle harness.
2. Attach P-clip to harness, secure to roof mounting
bracket with screw.
3. Lower the rear of the roof and secure.
4. Route harness along roof frame, fit cover plate and secure with screws.
5. Return the roof to halfway position and secure.
6. Attach P-clips to harness, route inside roof frame and secure with screws.
7. Align B-post trim and secure to roof frame with screws.8. Route harness under strap and secure to roof frame with
screw.
9. Route harness along tension strap and secure with Velcro straps.
10. Attach P-clips to harness and secure to roof header with
screws.
11. Connect motor multiplugs.
12. Secure wiring harness to motor mounting bracket with cable ties.
13. Secure insulation to header latch motor.
14. Install header assemb ly (see Workshop Manual
procedure 01.05.BB Panel Assembly - Header - Renew).
Roof Cylinder Wiring Harness-Renew
(Roadster Only)
Removal
1. Operate roof to halfway position with tonneau open. Support roof when hydraulic pressure drops with
suitable straps and support tonneau cover with suitable
prop (see Fig. 1).
2. Remove Quarter trim LH (see Workshop Manual procedure 01.05.CS Panel Assembly - Quarter Trim
Lower - LH - Renew).
3. Remove Quarter trim RH (see Workshop Manual procedure 01.05.CR Panel Assembly - Quarter Trim
Lower - RH - Renew).
Fig. 9
Fig. 10
Repair Operation Time (ROT)
ItemCode
Roof Cylinder Wiring Harness-Renew 18.01.AC
Fig. 1
Warning
Approximately 20 second s after the open/close
operation has been interrup ted the roof may suddenly
drop due to loss of hydrauli c pressure. If this happens
ensure no body parts are cl ose to the roof mechanism.
If the roof requires main tenance, support properly
using suitable props and straps.