QuestionQUESTION: My headlights cut out on me the other day while driving. Checked fuses, OK. I can flash the high beams only. The low and high beam switched to ON does not work. The high beam indicator lights when I flash lights. Not when switched to high beam.All other lights work.
ANSWER: Hi Bob,
Current goes to the light switch by a brown wire from the fuse. To test the light switch check for current on the blue wire going into the High/Low beam column switch. To test the column High/Low beam switch test for current on the blue with white tracer wire and the blue with red tracer wire coming out of the column switch when you operate high and low beam.
Howard
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QUESTION: I've checked the blue wire going into the column with key on. Power is present. Checked the blue/white with head lamp switch on, no power. Also checked blue/red with high beam on, no power. Power is ON blue/red, when I flash high beam.
I take it,the switch assembly will need to be replaced.The assembly part would be the high beam switch/turn signal assembly, and not the lower light switch on,off.
Thanks for your help.
ANSWER: Correct.
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QUESTION: Sorry to be a bother, but I opened the steering column, and found 2 fried wires going to the head light switch. I had a dead short a few weeks ago on the lights which blew the fuse. I fixed it, and lights worked for a short time. When I tested the blue wire in our first E-Mail, it was the large plug of wires. The fried wires were a different connector. The wire colors were 1-blue, 2-brown, 2-red/green stripe. The red and brown wires were the burn't ones. I replaced the wires, and checked the voltages. They are as follows.
With key ON, headlight Switch ON, Power is present on the blue,and red/green wires.
With key ON, Park lights ON only, Power present on RED/green, and brown wire.
Key ON,light switch OFF, no power to red/green, and NO power to Blue. Power on brown.
I used a test light to check power. I think the headlight switch is good, since it seems to be switching the power on both red, and blue wires. Hope this info helps.
Thank you.
Key on
AnswerHi Bob,
I think you are on the right track. check for power on the wires in the harness (car side) when you plug it back in. According to my "77" B diagram, the wires going to the high and low beams should be blue with a white tracer and blue with a red tracer. The short harness from the switch may as you see have different colors. All red wires with or without tracers (in the car harness) are smaller lights. Most switches are not made by the car manufacture and are used on other brands of cars so it is common to see different colors in their short harness.
The Lucas color codes in the British cars has been very consistent so that you can look in any British car harness and even without a diagram tell what many of the wires do.
Brown wires are power wires
Black are grounds
Blue are headlights
White are ignition
Purple are unfused accessories
Green are accessories
Tracers mostly are IDers too
A white wire with a black tracer is a ignition grounding wire.
A green wire with a black tracer is an accessory grounding wire.
Other traced wires are just for ID like the Blue headlight wires with white and red tracers etc.
You can work from either direction with your test light. some mechanics start at the head lights and work their way back to the dimmer switch and back to the light switch and on to the fuse. I usually go the route you are going, starting at the power source (fuse) then the brown power wire to the switch then the blue wire from the switch to the dimmer sw. and out to the car harness and it's blue wires with tracers. Then on to the headlight sockets and finally their grounds.
Howard
