Electrics: Headlight low beams both stopped working

[1966 122s]

Now I'm just being lazy, but I know someone will save me half an hour with the multimeter by telling me what usually causes this problem.......

Suddenly I have no low beam headlights. The high beams work just fine as do all other electrics on the car (including side lights when headlight low beams should be on)

So what is most likely ??????

[Derek UK]

Checked your foot dip switch? They can get very temperamental.

[jakobandhismakarov]

Check the wiring/ connections that run up the inner wings from the headlamps themselves.

I had this problem and had the lamps out and cleaned the terminals.......

....when what it actually was is that the two main connectors were twisted together with a soggy bit of tape. They worked fine on main beam, but went out \ dimmed on dipped. That's why the lights suddenly got better if you hit a large bump or clouted the wing in the right place...........

Incidentally, if you're still running on MOBO fixed beams, sack them off and get some Cibie H4s. I needed some new headlamps for my MOT back in 2007. They were damned expensive but give me a spread of light almost equal to that of my modern C4.

[capt jack]

Lighting relay? (The big six-pin one on the nearside inner wing)

Plus, bear in mind it's not unknown for two lamps to fail at once.......

Jack

[1966 122s]

Thanks for advice. I will spend an hour on it tomorrow.

I've never 100% understood relays. My impression is that there is a low ampage circuit through the dashboard switch which then activates the relay to complete a high ampage circuit from battery to light.

I hear a relay click when flashing high beam, but nothing when turning on / off low beam.

Derek..... Does fact that the foot switch still turns on / off headlight high beams rule it off the problem list ?

How would I go about testing the RELAY ?

[Alf ista]

Are they sealed beams or have you moved to halogens? If on sealed beams it reminds me of a problem I once had. At the back of the unit there are three wires. I assume, low beam, high beam and earth....? Anyway, my low beam on one of the lamps wasnt working. After messing around swapping lamps, what I discovered it to be in the end was just a bad connection at the back of the lamp. This is a very easy fix if it is the problem, so try taking off the connections, bit of a clean and then back on. If your lucky thats all it is.
Hugh.

[dandman]

Originally Posted by 1966 122s

Thanks for advice. I will spend an hour on it tomorrow.

I've never 100% understood relays. My impression is that there is a low ampage circuit through the dashboard switch which then activates the relay to complete a high ampage circuit from battery to light.

I hear a relay click when flashing high beam, but nothing when turning on / off low beam.

Derek..... Does fact that the foot switch still turns on / off headlight high beams rule it off the problem list ?

How would I go about testing the RELAY ?

hi , i would first check the foot switch .it switches both high and low beams .you should have a yellow cable supplying the unit when the main light switch is turned on .the outgoing grey is for dipped beams ,the red is for high beams . i would swap over the grey and red cables to check if your problem is reversed,or use your multimeter to see if you have a supply out on the grey when you call for dipped lamps .the relay you hear clicking is solely for flashing high beams .relays can be used for controlling items which draw high amperage .the control circuit would be unable to switch the circuit unless the cables and switches were sized upwards. the relay allows the power for the item to pass through it by having the relay coil energized by for example a toggle switch on the dash . I await to be contradicted by all and sundry ! DAN

[Derek UK]

"Derek..... Does fact that the foot switch still turns on / off headlight high beams rule it off the problem list ?"

The switch toggles between main and dip. If on main, push for dip. If on dip, push for main. The switch can get pretty rusty down there due to wind screen leaks etc. The 2 screws that hold it down might even be rusted in. Worthwhile cleaning it all up, including the connections. Possible that one has just come adrift.

[1966 122s]

Originally Posted by dandman

hi , i would first check the foot switch .it switches both high and low beams .you should have a yellow cable supplying the unit when the main light switch is turned on .the outgoing grey is for dipped beams ,the red is for high beams . i would swap over the grey and red cables to check if your problem is reversed,or use your multimeter to see if you have a supply out on the grey when you call for dipped lamps .the relay you hear clicking is solely for flashing high beams .relays can be used for controlling items which draw high amperage .the control circuit would be unable to switch the circuit unless the cables and switches were sized upwards. the relay allows the power for the item to pass through it by having the relay coil energized by for example a toggle switch on the dash . I await to be contradicted by all and sundry ! DAN

Thanks everyone. That honestly did save me an hour with the multmeter !

Foot swich was Ok so went straight to 8 block connector near left headlight and found the grey had voltage going into connector block but not out. The block wouldn't come apart easily and looked bodged / fragile so I've by-passed the block for the grey.

I am indeed on halogens... but they are a botched mismatched pair so I might go for new in near future. I hear mini suppliers are the source ? I'm going to guess that a trip to the scrap yard would have worked in 1980 but won't find a pair now.

[c.watkins]

What part of Ireland? We have our Amazon in West Cork (were your pics taken in Rosscarbery?). Cheers Chris