Dipped beam issue, odd one - 987s

[_bart_]

Good morning all, and hello!

 

Apologies if this has been covered before, but a search didn't reveal anything that matched my issue directly. Previous Sunday, our N/S dipped beam bulb failed, throwing a warning light. No issue there, figured it was simply the bulb and replaced with a nice new like-for-like. All good and used the car occasionally over the week / weekend. The other half then takes it to work on Monday and tells me that the warning light has come on again. 

 

Take out headlight, check bulb - all good (tested on 12v supply out of car). Check headlight coupling (visually) and see no corrosion, no misaligned pins, nothing to suggest issue. Take out other headlight, swap bulbs, issue still persists - N/S dipped beam warning. Put new bulbs in both lights, issue remains. Pull out dash switch, all appears functional and smooth, wiring in good condition. Checked power to the headlight, I have full beam, indicators, just only dipped beam not working on the N/S.

 

Before I go looking at either a new switch or perhaps even headlight, is there anything I'm missing!? I've seen a lot of posts about both dipped beams not working, but nothing around a singular light issue.

 

I'd really appreciate any help anyone could throw my way.

 

Bart

[futureechos]

I feel your pain, this was my position with N/S indicator a few weeks ago luckily it was a bent pin on the headlight itself where I had I had the headlights in/out 5+ times.

 

You've eliminated everything I can think of - I did find the headlight unit was a sod to get in out and lock in place due to fatigue on the headlight tool - it split at the end through continual use and wasn't gripping the nut to rotate the retaining bar to lock the light in place 100%. As you've had the lights in and out a lot you are probably aware but I guess check the light is locked in and see if it moves with the lights on to rule out bad connection due to seating position..

 

Only other thing is to borrow someone else's headlight unit to confirm if wiring/connector or the headlight unit itself.

 

good hunting.

[_bart_]

That's a good shout sir - I have lubricated the rotating bar that holds the unit in place, but might be worth me removing it entirely and checking it's all happy. 

 

I'll check again at that point that the dipped circuit has power

[_bart_]

Just tested the headlight itself by simply giving the unit 12v at the pins of the connector - all works as hoped. That means it's not a break in the circuit of the headlight, nor bulbs, and can only be I assume the circuit from the switch to the control unit?

 

However - is anyone able to confirm for me; I assume the circuit from the switch (if the switch was bad) would cause both dipped units to fail, not just one?

[_bart_]

The saga deepens, just tested with a multimeter the 12v feed at the plug harness from the car (that connects to the back of the headlight). Whilst I could see 12v for the high-beam, I seemed to find nothing for dipped (as expected considering the issue). However, I removed the orange rubber grommet and plugged it back into the headlight to check everything was working, and now I have absolutely nothing - no indicator, dipper or high-beam on that light. Everything is suggesting now that it is something to do with the wiring loom in the tub to the headlight :(.