Path: utzoo!utgpu!alliant.com!UUCP Reply-To: british-cars@alliant.com Errors-To: british-cars-request@alliant.com Sender: british-cars-request@alliant.com Return-Path: To: british-cars@alliant.com (local-british-cars) Newsgroups: local.british-cars Path: utzoo!utgpu!dambrose From: drivax!dambrose@amdahl.uts.amdahl.com (David Ambrose) Subject: Re: (none) Message-ID: <4BFDPMS@drivax.UUCP> Organization: Steppenwolf's Magic Theater References: <9001301719.AA12557@uunet.uu.net> Date: Wed, 31 Jan 90 16:10:12 EST Lines: 52 Newsgroups: list.british-cars Distribution: ut Approved: devnull@gpu.utcs.toronto.edu 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.