CDI Electronics Outboard Ignition Troubleshooting Guide

110 TROUBLESHOOTING GUIDE - Mercury Troubleshooting Mercury Troubleshooting 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. 10. 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. 11. Check the center hub triggering magnet in the flywheel. A loose magnet can cause this problem. 12. Check the triggering and charge coil flywheel magnets for cracked, broken and loose magnets. NO SPARK OR INTERMITTENT SPARK ON ONE OR MORE CYLINDERS: 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 + Brown Engine GND Open 0.2 V + 4. If (#1) or (#3) or (#1 and #2) or (#2 and #3) is not sparking, swap the White/Green and Green/White stator wires and retest. If the problem moves to the other cylinder(s), the stator is likely bad. If no change, replace all CDMs. A continued no spark condition on the same cylinder(s) indicates a bad trigger. 5. If #1 CDM module is not sparking, disconnect the #2 CDM module and see if the #1 CDM module starts sparking. If it does, the module you just unplugged is bad. If it does not, reconnect #2, then disconnect the #3 CDM module and see if the #1 module starts sparking. If it does, the module you just unplugged is bad. 6. If there is no spark on either # 2 or #3, swap locations with #1 and see if the problem moves. If it does, the module is bad. A continued no spark on the same cylinder indicates a bad trigger. 7. If the cylinders are only misfiring above an idle, connect an inductive tachometer to all cylinders and try to isolate the problem cylinders. 8. Check the resistance of each of the CDM modules (see NO SPARK ON ANY CYLINDER above). CDM OR TRIGGER REPEATEDLY BLOWS ON SAME CYLINDER: 1. Check the trigger wires for shorts to engine ground as a shorted trigger wire can destroy a SCR inside the CDM. 2. In contrast, a shorted SCR inside the CDM can destroy a trigger coil. Check the trigger resistance and DVA output (see NO SPARK ON ANY CYLINDER above). 3. Cut the Black/Yellow stop wire from the CDM not sparking. Measure DC voltage from Black/Yellow (from the harness) to engine ground. Turn the ignition switch on and off several times. DC voltage should never exceed 2V. If it does, the stop circuit has a fault. Check the key switch, harness and shift switch. 4. Replace the CDM on the cylinder dropping spark. MISS AT ANY RPM: 1. Disconnect the Yellow wires from the stator to the rectifier and retest. If the miss clears, replace the rectifier. 2. Connect an inductive tachometer to each cylinder in turn and try to isolate the problem. A high variance in RPM on one cylinder usually indicates a problem in the trigger or CDM module. Check the trigger DVA voltage (see NO SPARK OR INTERMITTENT SPARK ON ONE OR MORE CYLINDERS above). 3. Perform a high-speed shutdown and read the spark plugs. Check for water. A crack in the block can cause a miss at high speed when the water pressure gets high, but a normal shutdown will mask the problem. 4. Check the triggering and charge coil flywheel magnets for cracked, broken and loose magnets. 5. Rotate the stator one bolt hole in either direction and retest.