Can't dip headlamps

[duncan]

Posting both here and on NSX Prime.

I run gas discharge xenon ignitors and bulbs on all four headlamps.

Went to use car last night, fully rotated lighting switch; L & R headlamp retractors up, hi[full] and lo[dip] beams on, blue hi beam warning light on.
Pulled turn signal/dimmer switch to go to lo[dip] beam only – nothing –all 4 bulbs still illuminated.

I’m aware that when the main lights are on, both the hi[full] and lo[dip] have a common feed, and that for the lo[dip] position the earth to the hi[full] beam is interrupted.

Today; pulled ‘dimmer’ relay; relay fully operative, [switching coil energized – main [earthing] circuit complete; no power to switching coil – main [earthing] circuit broken]

HOWEVER; with relay removed, [earth to hi[full] beam broken] the hi[full] beam remains on.

Jumping/un-jumping the ‘dimmer’ relay socket – no difference the hi[full] beam remains on.
Pull fuse 52, one side, both bulbs go out; pull fuse 49, the other side, both bulbs go out.
Remove main lighting relay – all 4 bulbs go out.

No pun, any bright ideas of where to go next.

Thanks,
Duncan

[Sudesh]

Hi Duncan,

Can you describe your method of install of the Xenon/Hid?

Have you tried disconnecting the HID setup and going back to standard lights to see if there is a change?

[duncan]

The HIDs have been in place, and have been working OK for the last 4 years.
The spade to the H1 and bulb earth used to drive and earth the unit, no separate power or relays used, dip beam 55w rated, full beam 35w rated.
Disconnect HIDs and replace with bulbs as next step.

[Nick Graves]

How does your indicator switch 'feel'?

I wonder if the start-up spike of the switching hi beam on & off has fried it?

My DX95 driving lights did something similar to my X-1/9 many years back. Mind you, with spaghetti electrics, melting switches & sudden loss of illumination at speed on an unlit road was an exciting regularity. Even Karen's Uno did that to me once.

[duncan]

Kept dip HIDs, but replaced full beam HID lamps with halogen H1 bulbs; all now OK, full and dip operate normally and as expected.
Removed lamps, wiring and ballast units and bench tested these, both work fine.
Confused but relieved, I've no idea what caused the problem, all units were installed 4 years ago and worked OK until earlier this week, any ideas?
Thanks for looking.
Duncan

[Nick Graves]

Actually, IIRC the mains are relay-driven, so it's more likely the start-up spike's done some weird shi t to those, rather than the light switch. But Basically, after four years, something's taken exception to that spike.

Something stuck closed & caused an arse-circuit across all four blub connectors & the high beam self activated.

Possibly irritating the relays might have actually cleared it.

[Kaz-kzukNA1]

Hi, Duncan.

I think you have almost answered your own question in the first post.


As you stated, the dimmer relay controls the low side of the Hi beam bulbs and R & L Hi beam bulbs share the same low side circuit back to the dimmer relay.


If the Hi beam stayed On even after you removed the dimmer relay, then you created the GND circuit somewhere on the low side of the Hi beam bulbs before arriving at the dimmer relay.


This is the same even if you had the HID system installed at the Hi beam because with the way you connected it, the controller was getting the On/Off signal from the existing White and Black wire hidden inside the Headlight Hi beam housing.


There is a tiny chance that the HID controller latched its state but I’m quite sure you tried power cycling it using the head light switch so it is very unlikely to be the case.


As you have already disturbed the wiring, it is bit too late to check the followings but hope this will help in case if something similar happens in the future.


At the back of R & L headlight units, there is a 6pin grey connector ATTACHED to the unit itself.

There is another 6pin grey connector nearby but that is for the retractor motor so you need to look for the one attached to the unit.


If you follow the cable from this 6pin connector at the unit, you will find 14pin grey connector on each side.


On all of these 6pin and 14pin connectors, one of the wire is Red with Blue stripe on it (RED/BLU).


This is the wire for the low side of the Hi beam bulb and the two RED/BLU wires from R & L side are merged into one RED/BLU wire before arriving at the dimmer relay.


Therefore, even just a single short circuit to the GND on one side, it will switch On both side of the Hi beam.


If similar thing happens again, it is best to check the continuity to the GND at RED/BLU wire one section at a time by disconnecting the above connectors.


It is also possible that the 90deg angled connector at the White wire hidden inside the Hi beam housing unit was rubbing against the metal part of the head light unit.


For some reason, Honda used Black for the Positive side and White for the Negative (GND) side only inside the head light unit.


I believe you connected your HID control signal wires to these two wires.


Due to the nature of the retractable headlight, I saw several issues with the HID installation.


Some of the wires were not secured enough or got loose and shorted to the chassis metal part over the years.


The worst case I saw actually managed to cut through most of the cables at the retracter motor when the cable fixing got loose after many years...

Kaz