Corrected CB wiring diagram & switch contacts' matrices

[LOUD MOUSE]

<<<<<Ken, that's almost certainly an aftermarket combi switch.>>>>>. .............lm

just a daily driver. the first question is why i have two wires from the battery coming to this switch. i'm guessing the red through the fuse is the BA terminal, but why the second wire with no fuse to another terminal on the switch?

[e3steve]

Ken, the fused wire is the +12v supply that feeds all of the bike's consumers (ignition coils, starter, horn, brake light and riding lights [via the lighting switch]).

The unfused wire is the charging feed that hooks the rectifier +ve to the battery +ve. It's unfused because, should it become discontinuous whilst the motor is running, then the voltage to the consumers would become de-stabilised owing to the battery's sudden removal from the circuit. Without a battery present to cap the voltage, the most serious consequence could be the total failure of the ignition system.

If your bike still has the OEM selenium-diode rectifier, then I'd recommend replacing it with a modern silicon-diode type (instructional topics and posts here, on the forum, aplenty) and/or installing a 25-Amp fuse in the charging circuit wire. The selenium recs have been known to internally short-out, thus causing nasty burney-outey results!

[Ken184]

attached a diagram of the combination switch as is and a photo of the back of the switch.

[e3steve]

OK Ken, how many positions does the key turn to? Does it match the OEM switch?

OEM

• 1, OFF, key can be withdrawn
  2, IGN, key cannot be withdrawn
  3, PARK, key can be withdrawn

Please check the continuity as follows:

My prediction

• Position 1, should prove to have no continuity between any terminals
  Position 2, red > black, plus brown > brown/white
  Position 3, red > brown/white

Please confirm or deny.

NB: terminal 'CH' on the OEM switch is 'dumb'; ie, no connection to any other in any position. It's just a stud.

[Ken184]

key cannot be withdrawn in either position 2 or 3

continuity
Position 1 - no continuity (as you predict)
Position 2 - red>black, plus brown>brown/white (as you predict)
Position 3 - red>brown (not to brown/white)

there is no open stud but the red wire terminal also has a red wire jump to a fifth terminal stud

[e3steve]

OK Ken, connections as follows:

• Connect unfused red wire (from rectifier +ve) to red/white from battery +ve (these are usually sleeved with heat-resistant material) via a 25-Amp fuse
  Connect harness fused red wire to your ign switch red
  Connect harness black (and/or black/white) to your ign switch black
  Connect harness green to your ign switch brown/white
  Connect harness white to your ign switch brown

Position 2 should now allow you to start the bike and run all consumers; positions 1 & 3 should defeat position 2.

I'm surprised that the key can't be withdrawn in position 3, as that's PARK and should now present the parking light & taillight. Crappy-cheapo AM switch! But, hey-ho, it'll work in all other respects.

The harness's colours should correspond to those I've mentioned in the above list. Should they not, please let me know what colours they are; but you should have:

• Red (fused)
  Black (and/or black/white)
  Green
  White

plus the CHARGING CIRCUIT sleeved red and red/white.

G'luck!

[Ken184]

Clearly you understand this stuff, and it is really helping me, one step at a time. I don't understand these points;

in position 2, the red connects to the black and the brown connects to brown-white but the brown and brown-white do not connect to the red. how would the power get to the brown and brown-white?

the harness is separated a bit, so that i have two harness elements present at teh switch
the following wires to available to connect to the switch:
one contains only a black wire that goes only to the coils
the other harness has 1) another black, 2) a green, 3) a 'thickly insulated' white which appears to connect to the rectifier, and4) another white which connects to the tail light and i don't know what else.

The original setup had a thickly insulated white non-fused wire from the battery connected directly to the brown-white switch terminal. In position 2 that would connect the brown terminal to everything else on the bike except the black wire to the ignition coils, so everything got power from the brown including the rectifier. Should i now connect the battery directly (through a 25A fuse) to the 'thickly insulated' white wire to the rectifier?

The wiring diagram is confusing to me in this respect. it shows a red-white unfused wire from the battery connecting to the same terminal as the fused red wire and also to the rectifier.