Toledo Headlights Issues

[TriumphRUs]

Hello,

The headlights on my '74 Toledo stopped working. Sidelights come on fine and with stalk the high beam comes on as well just the main beam doesn't seem to work anymore. Any suggestions on what might be the problem or does anyone have a wiring diagram to check the wires?

Many Thanks

 

[RobPearce]

If you're on standard wiring, with no fuses on the headlights, then there are really only three faults that would cause loss of dipped beam but not high beam.

1) Both the dip filaments have blown at the same time. This can happen if there's a voltage surge but it's uncommon.

2) The common wire from the column stalk to the dip beam sub-harnesses has failed, or come unplugged.

3) The dip switch in the column stalk has melted. This, unfortunately, is very common and probably what has happened. With age, the contacts get dirty and slightly resistive. This means they drop some of the power in the contact, which gets hot, and the plastic moulding that holds them in place melts. The only fix is a new switch (not available for Toledo but there's a Mini part that is identical except for not having a chrome cap). Unfortunately the new switches are made of even softer plastic.

Whether or not you find you need a new switch, I strongly recommend fitting relays so that the current to the headlights doesn't go through the switch. It's more critical on the HL Dolomites and big saloons, with four headlights, but melted dip switches are common even on Toledos.

[TriumphRUs]

Thank you for your prompt and detailed reply.

As far as I can tell the wiring is standard without any fuses or relays.

Is the indicator/high beam stalk connected to the light switch which is on the dashboard?

Also would you happen to know what colour the wires are the dipped beam for me trace and check?

I will take the plastic cover off from the steering column and have a look for any signs of melted plastic and burnt wires.

[RobPearce]

Do you have a workshop manual? If not, get one! The wiring diagrams are all in there.

The main light switch on the dashboard has a positive feed from the battery and two outputs - one for side lights and one that goes to the column switch. That then has two outputs, for dip beam and high beam. Those wires should be blue/white and blue/red, although it's possible they change to that at the connector rather than being that colour all the way to the switch.

You will probably not see any burnt wires and you'll probably have to actually remove the switch and look closely to see where it's melted. It can be quite subtle and localised to the contact stud.