How to Use Circuit Diagrams

The Header joints outline the way in which internal harness splices and header joints distribute power in the harnesses. This information should be used during diagnosis of electrical faults to check for symptoms in associated circuits and narrow down the search area. Diagrams

Headers and splices
Header and splice tables present the joint(s) and wiring up to the first component. Splices are identified by a number with an alphabetical prefix and the wire colour.

The splice information shown on individual system circuits is not complete. Always refer to the splices circuit for complete information on each splice.

Wire attributes
Additional information (separated by a ',') is shown alongside the wire colour:
Wire gauge - the cross-sectional area of the wire in square millimeters. This is included to help you select the correct wire during harness repair.

Some wires do not have a gauge shown, these wires are of unique construction and will have a three or four letter code printed after the colour code, eg MAB. The code identifies the type of wire for manufacturing purposes. Usually, only the first two characters have significance in service, but in some instances the third character also becomes significant, see Wire Type information given below.

Wire type
The following table list the wire type codes together with an explanation of their meaning.

Code Description
MAB Twin core screened wire
MAH Coaxial screened wire
MAT Twin core double sheath
MCA Twisted core screened wire
MD* Twisted core ABS sensor wire
ME* Twisted pair of wires mm. 33 twists per metre
MM* Twisted pair of wires
MQ* Twin core foil screened cable
MZ* Three core screened flexible cable

Wire length (Power & Earth Distribution only) - the length of the wire in millimeters. This can be used to locate internal harness splices; look for the shortest wire between the joint and connector. For example it can be seen that C574-4 is 150 mm from joint A82.

Earth Distribution Diagrams
In Earth Distribution there are a number of Header and Splice tables. These are used in a similar manner to those in Power Distribution; to narrow the search area by checking for fault symptoms in associated circuits.







Connectors Connector Locations

Header joints are identified by their corresponding connector number with a numbered suffix to indicate the pin-out detail of the wire, i.e. C289-1 identifies connector 289, pin number 1. Wire insulation colour is identified in the normal way. Where wires have a predominant colour with a secondary colour stripe, the main colour is identified first, i.e. LGS - Light Green with a Slate stripe.







Line Types
This means the wire connects to another circuit.







The cup and ball symbol indicates the male and female halves of connector.
A. Plug on lead (Flylead) wired directly to the component.
B. Connector plugs directly into component.







Components
The name or description of the component is shown. A dotted outline indicates that the components not shown in its entirety.







Earth points Ground Locations
Earth points are identified with an eyelet symbol and a connector number, except where components are grounded through their fixings, when only the eyelet is shown.







Fuses and Diodes Power and Ground Distribution
Fusible links (A) and current rated fuses (B) are identified as shown

The direction of the arrow in a Diode symbol (C) indicates the direction of current flow. The Zener diode (D) - prevents current flow until a precise voltage is reached.