CDI Electronics Outboard Ignition Troubleshooting Guide

108 TROUBLESHOOTING GUIDE - Mercury Troubleshooting Mercury Troubleshooting Mercury/Force Two Cylinder Engines 1994-2006 Engines Using CDM Modules NO SPARK ON ANY CYLINDER: 1. Disconnect the Black/Yellow stop wires from the harness and retest. If the engine’s ignition sparks, the stop circuit has a fault. Check the key switch, harness and shift switch. 2. Disconnect the Yellow wires from the stator to the rectifier and retest. If the engine now has spark, replace the rectifier. 3. Check the cranking RPM. A cranking speed of less than 250-RPM will not allow the system to spark properly. This can be caused by a weak battery, dragging starter, bad battery cables or a mechanical problem inside the engine. 4. Inspect the spark plug wires, boots and spark plugs. Check for chafing on the wiring and harnesses. 5. Inspect and clean all engine and ignition ground connections. 6. Pull on each wire from each CDM harness plug. Make sure all wires are making proper contact inside plugs. 7. Disconnect one CDM module at a time and using a set of piercing probes and jumper wires - short the stator wire in the CDM connector to engine ground. Retest. If the other module starts sparking, the CDM you unplugged is bad. 8. Check the stator resistance and DVA output as follows: W IRE READ TO OEM RESISTANCE CDI RESISTANCE DVA (Connected) DVA (Disconnected) White/Green Green/White 500-700 400-550 180-400 V 200-400 V (*) (*) This reading can be used to determine if a stator or the CDM modules have a problem. For instance, if you have no spark on any cylinder and the stator’s DVA reading is low – disconnect the stator wires and recheck the DVA output. If the reading stays low – the stator is bad. If the reading is now within spec – at least one of the CDM modules is bad. 9. Check the resistance of each of the CDM modules as follows: RED METER LEAD BLACK METER LEAD READING CDM Pin # A C 1200-1400 Ohms CDM Pin # D A DIODE* CDM Pin # A D DIODE* CDM Pin # D B DIODE* CDM Pin # B D DIODE* CDM Pin # A B DIODE* High Tension Lead A OEM 700-1300 Ohms – CDI 2200-2400 Ohms * Diode readings are to be read one way, then reverse the leads and read again. You should get a low reading in one direction and a higher reading in the other. 10. Check the center hub triggering magnet in the flywheel. A loose magnet can cause this problem. 11. Check the triggering and charge coil flywheel magnets for cracked, broken and loose magnets. NO SPARK OR INTERMITTENT SPARK ON ONE CYLINDER: 1. Inspect the spark plug wires, boots and spark plugs. Check for chafing on the wiring and harnesses. 2. Clean and inspect CDM ground wire connections to engine ground. 3. Check the trigger DVA output as shown below: WIRE READ TO RESISTANCE DVA (Connected) Purple Engine GND Open 0.2 V + White Engine GND Open 0.2 V + 4. If one cylinder is not sparking, swap the White/Green and Green/White stator wires and retest. If the problem moves to the other cylinder, the stator is likely bad. If no change, replace both CDMs. A continued no spark condition on the same cylinder indicates a bad trigger. 5. If the cylinders are only misfiring up above an idle, connect an inductive tachometer to all cylinders and try to isolate the problem cylinders. 6. Check the resistance of each of the CDM modules (see NO SPARK ON ANY CYLINDER above).