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115 mercury swith box test

bass_tracker

Contributing Member
Hello,

I read on here a while back how to test a switch box on a 70's model mercury 115 can someone that knows how to do that repost it please I got one i need to check.

Thanks for help.
 
The acceptable voltage range for battery type ignitions is typically 9.5 Volts (at cranking) to a maximum of 16 volts at full throttle
(13.2-14.6 preferred). Voltages above or below this range can cause damage to the CD.
DO NOT USE A MAINTAINENCE FREE, DRY CELL OR AGM BATTERY WITH ANY BATTERY DRIVEN CD UNIT!
No Fire on Any Cylinder:
1. Clean all battery connections and engine grounds.
2. Disconnect the mercury tilt switch and retest. If the ignition works properly, replace the mercury switch.
3. Connect a spark gap tester to the spark plug wires and check for fire on all cylinders. If some cylinders fire and not
others, the problem is likely in the distributor cap, rotor button or spark plug wires. Notice: If the unit only fires when
you let off of the key switch, the trigger is usually the problem.
4. Check voltage present on the White wire at cranking. It MUST be at least 9½ volts. If not, the problem is in the
harness, key switch, starter or battery.
5. Check voltage present on the Brown wire at cranking. It MUST be at least 9 volts. If not, the problem's likely in the
pack.
6. Check DVA voltage on the Green wire going to the coil. It should be approximately 200 volts at cranking.
7. With the spark gap tester to the high tension lead coming from the ignition coil, disconnect the Brown, White and
Black trigger wires. Connect a jumper wire from the slot for the Brown wire to the slot for the White wire. Connect
another jumper to the slot for the Black wire and (with the key switch turned on) strike the jumper against engine
ground. The unit should fire each time. If it does, the CD module is usually good.
 
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