Glow plug Porsche Allgaier– . BERU equivalent 1.7 V DC Best value in EU– When you pull the starter switch to position 1 –the 12 Volt power is fed from the battery through the resistance coil , through the glow plug watcher element & through the glow plug or plugs in series making the whole circuit a 12 volt circuit ( 10.5 V under load)
If 10.5 Volt glow plugs fitted then the resistance coil is taken out of circuit and the plugs are wired in parallel or buy our book on this subject & much more
