Wiring Harness Service - Mercury MerCruiser D2.8L D-Tronic Service Manual

SERVICE MANUAL NUMBER 22

Wiring Harness Service

GENERAL INFORMATION
Marine engine control circuits contain many special design features not found in standard
land vehicle wiring. Environmental protection is used extensively to protect electrical
contacts. Proper splicing methods must be used when making repairs.
The proper operation of low amperage input/output circuits depends upon good continuity
between circuit connectors. It is important before component replacement and/or during
normal troubleshooting procedures that a visual inspection of any questionable mating
connector is performed. Mating surfaces should be properly formed, clean and likely to
make proper contact. Some typical causes of connector problems are listed below.
•
Improperly formed contacts and/or connector housing.
•
Damaged contacts or housing due to improper engagement.
•
Corrosion, sealer or other contaminants on the contact mating surfaces.
•
Incomplete mating of the connector halves during assembly or during subsequent
troubleshooting procedures.
•
Tendency for connectors to come apart due to vibration and/or temperature cycling.
•
Terminals not fully seated in the connector body.
•
Inadequate terminal crimps to the wire.
Wire harnesses should be replaced with proper part number harnesses. When signal wires
are spliced into a harness, use the same gauge wire with high temperature insulation only.
With the low current and voltage levels found in the system, it is important that the best
possible bond be made at all wire splices by soldering the splices, as shown in Wire Repair.
Use care when probing a connector or replacing connector terminals. It is possible to short
between opposite terminals. If this happens, certain components can be damaged. Always
use jumper wires with the corresponding mating terminals between connectors for circuit
checking. NEVER probe through connector seals, wire insulation, boots, nipples or covers.
Microscopic damage or holes may result in eventual water intrusion, corrosion and/or
component or circuit failure.
90-860074--1 FEBRUARY 2002
EDI DIAGNOSIS
Page 5E-99