ammeter

[Stuart Giles]

I presume it is possible to select headlamps and summer charge together? The form of the wiper(s) in the ign/charge switch are not obvious

Hi Bob,
          It shouldn't be possible to have half charge and the headlamps on. I don't have a diagram but this "work in progress" photo of an SM5 I restored recently should help. The "A" terminal is hard wired to the centre posts of both the ignition/charge and lighting switches. When "Full charge" is selected the roller that is visible just below the ammeter on the right is pushed by the brass wiper and shorts the "D+" terminal on the back of the switch panel to the "Shunt" connection on the back, so shorting out the half charge resistor. The roller on the left side will be operated when the lighting switch is set to "Head" -this shorts the "D" to shunt in the same way as on the ignition side. So when the panel is working properly i.e. without 80 something years of tarnish on the roller's Phosphor Bronze spring and on the Brass D+ terminal post, an unthinking owner can't run the battery down in no time at all during night driving.