Hi Buzz,
Did the ohms test on the coils LT, got 1.9 ohms.
So they're probably good.
did bypass as you recommended.
But still have the battery load-tested.
When I turn the key on, voltage drops to about 4.5 volts going to the coils.
bypassed the light switch #2 terminal and still got a voltage drop from 6.09 to 5.60 when switched on.
It's possible you have some Volts drop across both switches.
Reconnect the coils and the end of the wire from the Ammeter back to Lighting switch terminal #2.
Trickle-charge the battery for a long period (say overnight?). After you reconnect the battery to the bike's electrics, turn the ignition switch key on for a few seconds then turn it off again - this will dissipate any 'surface charge' which could give a misleadingly-high meter reading.
1. Everything turned off, connect the meter across the battery; note the meter reading.
2. Turn on the ignition, note the meter reading (4.5V?).
3. Leaving the meter lead end connected to battery +ve, move the other meter lead end from battery -ve to the nearest Ammeter terminal, note the meter reading; if it isn't the same as at 1., there's a problem between the battery -ve terminal and the Ammeter.
4. Move the meter lead end from the tested Ammeter terminal to the other Ammeter terminal, note the meter reading; if it isn't the same as at 1., there's a problem in the Ammeter.
5. Move the meter lead end from the Ammeter terminal to Lighting Switch terminal #2, note the meter reading; if it isn't the same as at 1., there's a problem between the Ammeter and terminal #2.
... and then to Lighting Switch terminal #10, and then to Ignition Switch terminal #12A, and then to Ignition Switch terminal #13 and finally to the coil -ve terminals; each time noting the meter reading; any time it isn't the same as the previous reading, there's a problem in the component between the two tests.
Referencing the wire diagram, I see green/white from alternator to rectifier, also to #4 on the light switch. According to 88SA switch positions, the only time this terminal (#4) is in contact is with #5 when in the off position. My question is why does the wire connect to #4 when it apparently breaks contact with all other terminals when switched to on positions?
Mmmm ... 'scuse me while I
... this is part of what Lucas called 'charge control' before the Zener diode ...
Electricity and magnetism are interconnected. Lucas (most) motorcycle alternator rotors are permanently-magnetised (others are electro-magnets). Put a magnet near a coil of wire, the magnetism induces electron movement within the wire, electron movement is the basis of electricity.
Upside of permanent-magnet alternators is they're simple, downside is they generate electricity anytime the rotor's ... errr ... rotating ... and the faster the rotor rotates, the more electricity it generates. Which is great when you speed up at night leaving town - headlamp's on, battery needs charging, etc. ... but not so great when you're riding along in sunshine, battery fully-charged, all lights off ...
To cope with these varying electrical conditions, Lucas had the Ignition and Lighting Switches also connect some of the alternator stator coils differently. The system is pretty-good 'in theory'; in practice, it couldn't cope with the realities of crap assembly, no maintenance and unforeseens like blown bulbs. You and the bike'd be way, way, wa-aa-ay better off with a discreet 6V reg./rec. and dispensing with all the standard junk; "the past being a foreign country", standard Lucas pre-Zener charge control is the bits of the world where humans still eat each other.
green/white from alternator
#4 on the light switch.
The alternator stator has six coils, connected together in three 'series pairs'; i.e. a given coil is connected at one end to another coil and at the other end to one of the three wires out of the stator:-
. One coils pair is connected to the Green/Black wire at one end and the Green/White wire at the other end; these are the (stator) 'ignition' coils, in that they power the ignition and charge the battery.
. The other two coils pairs are connected to the Green/Yellow wire at one end of each pair and the Green/White wire at the other end of each pair; these are the 'lighting' coils, in that they're only 'switched in' when you turn the Lighting Switch to "H".
However, as I posted above, electron movement (generating electricity) is being induced in
all stator coils
any time a permanently-magnetised rotor is rotating. When lamps are switched off, to turn the unused electrical energy in the lighting coils into heat that could be radiated, the Ignition and Lighting switches connect the stator lighting coils' Green/White and Green/Yellow wires together (this is sometimes described as 'shorting' the coils but, in reality, there isn't any other power source and all stator coils have some resistance).
"connect the stator lighting coils' Green/White and Green/Yellow wires together" is done by:-
. you've seen "green/white from alternator to ... #4 on the light switch" already;
. "the only time ... terminal (#4) is in contact is with #5 when in the [
lights] off position";
. terminal #5 is connected to Ignition Switch terminal #18 by a Blue wire;
. terminal #18 is connected to terminal #17 when the Ignition Switch is in the "IGN"(?) position (the engine is normally running, the alternator is generating);
. terminals #17 and #16 are connected internally;
. Green/Yellow is connected between terminal #16 and the alternator stator.
why does the wire connect to #4 when it apparently breaks contact with all other terminals when switched to on positions?
Engine running, Lighting Switch "OFF", the stator ignition coils' output is depressed by the magnetic effect of the current flowing in the 'shorted' stator lighting coils.
Lighting Switch turned to "L", greater output from the stator ignition coils is desirable, the switch position disconnects terminal #4 from terminal #5 to break the connection between the lighting coils' Green/Yellow wire and the Green/White wire.
Lighting Switch turned to "H", the stator lighting coils are 'switched in' - connected to the rectifier:-
. as above, stator Green/Yellow is connected to Ignition Switch #16, #16 and #17 are connected internally, switch in the "IGN" position connects #17 to #18, Blue wire connects #18 to Lighting Switch terminal #5 ...
. Lighting Switch #5 and #6 are connected internally, Lighting Switch in the "H" position connects #6 to #7, #7 is connected by a Green/Black wire to the same rectifier AC terminal as the stator Green/Black wire (i.e. the opposite rectifier AC terminal from the Green/White wire).
However, as I've written above, the problem with this charge control system is it looks good in theory, in practice you find out about a failure with a boiled and/or dead battery; e.g. Lighting Switch in the "H" position, headlamp bulb blows and you don't know about it (say riding in daylight), first thing you know is acid boiled out of the battery over the bike or, if it's a sealed battery, it's 'blown'.
Otoh, a 6V reg./rec., you connect stator Green/Yellow and Green/Black together to one reg./rec. AC (Yellow?) wire, stator Green/White wire to the other reg./rec. AC wire, reg./rec. Red to battery +ve, reg./rec. Black to battery -ve, the reg./rec. automatically and quietly handles all the different electrical supplies and demands, you simplify the bike's wiring by junking all the 'charge control' wiring.
Hth.
Regards,