Part V


By E. Meloan

(This article was originally published in the November, 2003 issue of the Spark Coil.)

Howdy, Fellow Model T’ers!  Let’s continue our discussion of the Model T electrical system.  In our last article, we touched briefly on the terminal block used in the cars equipped with starters and generators.  I’d like to spend a little more time on the details of the terminal block and wiring.

I’ll use the 6 screw block in my discussion since it is the most common.

I mentioned the terminal block as a common source of problems in the last article and since this is so important, I want to emphasize it again.  Unless your terminal block has been replaced, it is very likely to have screw holes which, because of age and wear, will not hold the wires in tight contact!  The connections on the terminal block control every circuit except the starter and are a frequent source of intermittent electrical problems!  It is very important that your  check this block carefully and if it can’t hold the screws TIGHT, repair or replace it!

Let’s go over the wires that attach through the terminal block.  Looking at the block from the front of the car, and starting on the left, we have the following attachments.

Terminal # 1 (GEN) should have two or three wires attached.  A yellow wire with a black tracer to the generator cutout and a yellow wire with a black tracer to the ammeter.  If you want the horn to show a discharge on the ammeter when blown, then also connect the black wire from the horn button to terminal # 1.

Terminal # 2 (MAG)  A red wire from the magneto post on the flywheel housing (routed
Under the firewall) and a red wire to the magneto terminal on the dashboard combination ignition/light switch.

Terminal # 3 (BAT)  A yellow wire from BATTERY side of the starter switch and a yellow wire to the ammeter.  Normally the generator wire goes to left terminal on the ammeter (looking at the back of the meter) and the BATtery wire goes to the right terminal of the meter.  If the meter shows a charge when the lights are on and the engine is not running, reverse positions of the two wires on the back of the ammeter!

Terminal # 4 (TAIL)  A black wire to the tail light and a black wire to the TAIL terminal of the ignition/light switch.   I also like to connect a dash light to this terminal so that it is switched on whenever  the lights are on.

Terminal # 5 (DIM) Headlights.  A black with red tracer wire to each headlight and a black with red tracer wire to the DIM terminal on the ignition/light switch.

Terminal # 6 (BRT) Headlights.  A black with green tracer wire to each headlight and a black with green tracer wire to the BRIGHT terminal on the ignition/light switch.

If your car uses twin filament bulbs, the bulb will have one filament centered in the bulb and a second filament off-center in the bulb.  Bulbs should be put in the socket so that the centered filament is on when BRIGHT is selected and the off-center filament is on when DIM is selected.  The off-center filament should be above the centered filament so the beam is thrown down on the road by the reflector.

The Model T electrical system can be very reliable if we just take care of it.

See you down the road…