1959 G80 PRS8 switch.

[chrismorgan]

I have just been wiring in a new PRS8 switch to my recently acquired 1959 G80. Everything has gone according to the wiring diagram except that I have a light green wire in the headlight shell that appears to come from the rectifier but does not appear on any wiring diagram that I can find. Can anyone tell me which terminal on the switch this wire is supposed to connect to. I have the dark green and purple wires from the rectifier connected O.K. The ammeter shows no charge running it as it is.
Chris.

[Mick D]

Hi and welcome Chris

Without confirming where the LG wire comes from it's impossible to guess where it should go. I suggest you arm yourself with some form of continuity tester and identify which wires you currently have connected correctly. Start with the ones which run into the headlamp, (tail NG, Stop NU, Alt GY).

Do you know the ammeter works? if not connect the battery with a headlamp bulb in series across the ammeter and confirm you get a deflection.

Regards Mick

[chrismorgan]

The LG wire comes from the alternator to the rectifier where there is a double piggy-back connection (looks original) and then goes up to the headlamp. All the other wires are connected as per the colour codes in the wiring diagram and everything works as it should. The ammeter shows a discharge when the ignition is tuned on and goes back to zero when the points open on turning the engine over. The engine starts and runs fine but the ammeter shows no charge. I have tested the resistance of the coils in the alternator and they appear to be fine. This light green wire is embedded in the loom and looks to be completely original I just have no idea where it is supposed to connect to. If the wiring to the PRS8 switch hadn't been such a mess to start with life would have been a whole lot easier.

Regards Chris.

[billbeavis]

Hello Chris, You appear to have the 6 volt original system. The one and only LG wire I see on my x2 diagrams is alternator to rectifier (single wire connection only). Other alternator colours are green and yellow direct to switch 16 (linked 17) and dark green to rectifier then on to switch 7. Third wire on rectifier is purple to switch 13 The switch links all need to be in place. With 6 volt system there is some switching in of alternator coils depending on lights switched on. Ammeter seems to be ok if shows discharge but could test for positive swing with on ignition by swapping over the connections temporarily (disconnect battery while doing swap over). Bill

[Mick D]

Hi

To clarify:

Do you have two double connections on the rectifier DC outputs, (LG and DG)? - If so I'd suggest the LG from the rectifier to switch is redundant.

Do you have a multimeter with which to check the voltage at the battery with the engine running, lights on and off?

Regards Mick

[chrismorgan]

Hi Bill and Mick,

I think I have found the answer. My 1954 Triumph Thunderbird has an almost identical electrical system and when I looked at the Triumph wiring diagram it shows that Light Green wire going to terminal 4 on the switch. It seems that the diagram in the Matchless manual has just omitted it. I'll wire it in tomorrow and let you know if it has resolved the problem.

Regards, Chris.

[chrismorgan]

Thanks for the help. The light green wire does indeed connect to terminal 4. The wiring diagram in the Matchless book has just not shown it.

Regards , Chris.