Fog light activation causing headlight pod vibration

[johnnybegood224]

While checking out the cabin instrument operation (with the car stationary) I came across an oddity. With the headlights on, when the front fog lights are switched on (they both work fine), the drivers/off side headlamp pod begins to vibrate/knock. When you lightly place you hand on the headlight it feels as though there is some kind of cam operating from below which is bouncing the pod up and down, if you take the weight off the headlight and raise it slightly the knocking stops, any ideas.
One other thing that's maybe worth a mention, the offending headlight pod sits slightly lower than the other side.

[Hawaiis0]

I would look at the pod adjustment as the limit switch for fully up position may not be made and it is trying to cycle fully up. Hence applied pressure upwards completes the up cycle removing the command supply but is reactivated when released and sags down. Start by screwing the stay bar in for example. This will allow the actuator to travel further. Do your pods have buffer stops fitted?

[Hawaiis0]

Any sign the pods have been replaced in the past? There are 2 types so possible one is incorrect. They should be etched with the chassis number to confirm

[johnnybegood224]

Thanks for the reply Hawaiis0, I will have a look into the points you have made, what I can't understand is why pushing in the front fog light switch in is causing this bouncing of the headlight pod (if I just turn the headlights on, the pod rises and sits without any issue).

As I only really used the car in daylight and in good weather I dont think I've ever had cause to use the front fogs so its probalbly been like this since the repair

To answer your question, there is a chance that the pods were replaced, as the car suffered from a front end accident.

regards John

[Alan_M]

Might it be worth checking the earth points in case there’s some current leakage triggering the headlamp motors?

[Hawaiis0]

Bad earth - is definitely a good shout.

There is a commonality in the FHC (front harness connector) - pins 1; 2; 3 and 4 for retraction relay and 11 for fog lights. Is there any moisture present?

[CHRISYD]

Yes it does sound like the neutral is getting a Ghost feed from fog live confusing the lift motor. if the motor gets a real live feed and neutral one at same time the motor will vibrate slightly as its trying to rotate both ways at once.

[johnnybegood224]

Thanks all, earth points and relays checked and cleaned/secured, issue no longer evident.

ps Now I'm spending time fixing issues and getting the Lotus ready for selling I'm starting to re appreciate what a good car she is

regards John

[Pete Boole]

And less far rusty than Abingdon products! . You should sort it and keep it!

Pete