In article <9001301719.AA12557@uunet.uu.net> att!speedy!gerry@uunet.uu.net
writes:
>> I'd been assuming that the switch had just died. But now that there are
>> two high current things broken, I"m starting to wonder. I don't trust
>> my 4A wiring diagram -- does anyone know if the headlamp current might
>> be wired through the key switch?
>
>I doubt it, most older Brit cars that I have worked on, have the lights
>wired independant of the ignition switch, I have not worked on any
>Triumphs so this may not be the case here.
>
>> Set out to drive Sarah (my TR4A) tonight and discovered that the
>> headlights don't work any more. Everything else does, though -- just
>> the headlights. The 'main beam' indicator is on.
>
>Trace the wires coming from the back of the headlights to where they
>are crimped on to those black connectors that Lucas use. Take out the
>wires from the connectors and clean them with some emery paper. You
You didn't say how brightly the high beam lamp was glowing, but
I'll hazard a guess that something like this is happening (pardon the ascii
schematics)
BATTERY-------HeadlampSwitch----+---------------------LowBeam---|
| |----Highbeam sw--+---HiBeam----|
| | |
GND0 Hibeam ind. |
| |
GND1 GND2
Normally current flows straight from the battery to the
HeadLampSwitch the LowBeam and then to GND2. However, if GND2 gets
disconnected, then current flows from the Battery to HeadlampSwitch to
Lowbeam, to Highbeam, to the Hibeam ind. and then to GND1. Both headlamp
filaments glow very little (if any) because most of the voltage is dropped
across the Hibeam indicator.
Theis can be checked by manually connecting the headlight ground and
seeing of the symptoms clear up. Unplugging the recalcitrant headlight(s)
should cause the hibeam indicator to go out.
Good Luck,
Dr. Vorch
--
Play it cool; play it cool; fifty-fifty fire and ice -- Joni Mitchell
David L. Ambrose, -- Digital Research, Inc ...!amdahl!drivax!dambrose
Don't blame DRI. They wouldn't approve of this anyway.
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