MEFI Fuel Injection
Data Link Connector Master/Slave Connector
The data link connector (DLC) has 5 wires in a 10 cavity connector. Cavity A (black) is the ground for the scan tool (VP-2000, Techmate). If this ground is open, the scan tool will not communicate with the ECM. Cavity B ( white with a black tracer, or black with a white tracer) contains the diagnostic test terminal circuit. The ECM puts 2.5V on this wire. When this wire is grounded with no CKP (crank sensor) input, the ECM flashes codes at cavity E (green with a yellow tracer) by toggling the wire to ground through J1-27. Some vessels will have a check engine light bulb connected to this wire. If the wire at cavity B is grounded with the engine running, then service mode is entered and the engine will idle at 1000 rpm and timing is locked down to base timing. Cavity F (red with a purple tracer) is power for the scan tool (VP-2000, Techmate). This is the same circuit that powers up the ECM at connector J2 pin 1. Loss of this circuit to the DLC will cause loss of communication between the ECM and the scan tool due to no power at the scan tool. Cavity G (orange with a black tracer) is the serial communication wire. All communication between the scan tool and the ECM occurs over this wire. The Master/Slave connector has 2 wires, the orange with a black tracer and a yellow with a green tracer. The yellow with a green tracer wire is the master/slave wire. The ECM puts 11.5v on this wire. When this wire is grounded, it indicates to that ECM that it is the slave ECM in a twin engine setup. The orange with a black tracer is the communication wire. If the technician has a master/slave cable kit (3857221), the engines can be temporarily connected together so the scan tool (VP-2000 or Diacom) can gather information from both engines at the same time.
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