The Scenario:
My car has some dirty switches around the steering wheel column which stop the indicators / park lights from working correctly all the time, so I always check my lights before driving the car on the road. Typically the fix is just to jiggle the loom / spray loom with WD40 around the connections and then everything is cool.
I decided to make these tests easier so i opened the tail gate up and swung it around so that i could stand next to the drivers seat and see the tail lights whilst touching the brake and / or controlling the headlights / indicators.
The Issue:
On this occaision things were a little wierder than normal:
1. Turn on R indicator - works fine
2. Turn on L indicator - works fine
3. Touch Brake - works fine
However, turn on the headlights and repeat:
1. Turn on R indicator - works fine
2. Turn on L indicator - all park light flash instead (including front).
3. Touch Brake - all indicators light up instead (including front).
4. Turn on Hazards - number plate light flashes instead.
So there you have it. So i worked around with this issue for a good hour and a half checking all the earths that i was aware of, and making sure that the terminals around the steering wheel column were working correctly.
Eventually I gave up and drove home very carefully - trying very hard to make sure no one was behind me when i used the brakes, and never indicating (staying in the left hand lanes etc)... (it was dark so i had to have the lights on)...
Got home and thought - okay - lets just check the lights out again - they worked fine
... Now - very confused I went inside and pondered the issue a bit further.
The next day I reckoned I had a possible solution that could be the fix. So out i went to check out the car again and try to stamp out the issue.
I repeated the tests with the lights off, and all was well.
I repeated the tests with the lights on - and all was well.
Then I did something that made everything go haywire again.
Guesses?.....
Okay - you give up...
I opened the tail gate. - everything went haywire again. shut the tail gate and everything was normal
I gather that the current could not get back via the door hinges as well as it might have liked, but when the door was shut - the door latch provided sufficient earthing for everything to work correctly.
Wierd.
So i think i'll attach a wire from the tail gate to the body to bypass the hinges from now on. That'll allow me to use the "tail gate open" system for checking the lights, but still keep everything earthed correctly.
Note: my tail lights are mounted in the tail gate so this is only really relevent to people with this setup - but i just thought it was a wierd story worth sharing
