switchbox troubleshouting

izu

Seaman
Joined
Jul 2, 2007
Messages
55
How can I determine if a faulty switch box is causing my 6 cyl merc's rough idle condition.
 

Plainsman

Rear Admiral
Joined
Apr 2, 2006
Messages
4,062
Re: switchbox troubleshouting

Depends on the year, but this might work for you:

CREDIT TO CLAMS FOR THIS


do you have 12V to the red terminal on the switch box?

do you have 12v at the white terminal when the key is turned on?

MERCURY BATTERY-POWERED CDI SWITCHBOX TEST
FOR DISTRIBUTOR MODELS


This test is for the 332-2986 switchbox used from 1967-1978 on all the
inlines.

This test assumes your coil is good (most all are).


Disconnect the mercury switch (kill switch)

DISCONNECT BATTERY

1. Turn off ignion
2. Disconnect all 3 wires on the distributor side of the switchbox.
3. Remove the HV lead from the coil to the center cap (remember it unscrews
from cap)
4. Reconnect that HV center lead to the COIL side only.
5. Position that HV lead about about 3/8" from ground (block, shrouds etc)
and find a way to hold it there.
6. Jumper the brown and white terminals on the dist. side of the switchbox
together.

RECONNECT BATTERRY

7. Check that you have +12 V at red terminal.
8. Turn on ignition and verify +12V at white terminal (on red terminal side)
9. Touch the black terminal to ground - unit should cause spark each time
you touch ground.

If that passes and it won't fire at all, suspect the trigger.
 

izu

Seaman
Joined
Jul 2, 2007
Messages
55
Re: switchbox troubleshouting

Depends on the year, but this might work for you:

CREDIT TO CLAMS FOR THIS


do you have 12V to the red terminal on the switch box?

do you have 12v at the white terminal when the key is turned on?

MERCURY BATTERY-POWERED CDI SWITCHBOX TEST
FOR DISTRIBUTOR MODELS


This test is for the 332-2986 switchbox used from 1967-1978 on all the
inlines.

This test assumes your coil is good (most all are).


Disconnect the mercury switch (kill switch)

DISCONNECT BATTERY

1. Turn off ignion
2. Disconnect all 3 wires on the distributor side of the switchbox.
3. Remove the HV lead from the coil to the center cap (remember it unscrews
from cap)
4. Reconnect that HV center lead to the COIL side only.
5. Position that HV lead about about 3/8" from ground (block, shrouds etc)
and find a way to hold it there.
6. Jumper the brown and white terminals on the dist. side of the switchbox
together.

RECONNECT BATTERRY

7. Check that you have +12 V at red terminal.
8. Turn on ignition and verify +12V at white terminal (on red terminal side)
9. Touch the black terminal to ground - unit should cause spark each time
you touch ground.

If that passes and it won't fire at all, suspect the trigger.
its a 1984 model
 

Plainsman

Rear Admiral
Joined
Apr 2, 2006
Messages
4,062
Re: switchbox troubleshouting

Sorry, but that's all the info I have. Someone will be along to give you a hand.
 
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