Head lamp mod - relay Q

[RichardW]

I am in the process of relaying the headlights on the Xantia. Done the NS but ran out of cable and spades to finish the OS. Much brighter I will also double up the earths I think while I am at it. I've got change over relays (because they were available cheap!) and I've currently wired it power onto the common pin 30, as this seems to my mind the std way to wire it up - this leaves one of the pins live all the time the relay is not energised (ie headlamps off). Just wondering if there is any reason I can overcome my in built thoughts and wire it the other way - power to 87a and feed out to lights on 30 - so the other pin is never live? My only thought is that this might cause burning on the relay contacts as it switches, but maybe I am being over cautious - it is a 40A relay only handling about 5A after all!

I dropped the headlight out (surprisingly easy!) and drilled a small hole in the bottom to run the new cable in, with a new spade on the end. I cut the wire to the existing plug, and then put an extension on to feed the relay, this way I can easily revert to non-relay operation if desired.

Few jobs this weekend - OS headlight, accumulator, indicator swtich - and the Picasso needs new drop links. Probably put off the Xantia rear ABS sensor change for now - the light is only intermittent at the moment (although it is becoming more frequent and a couple of times has failed to go out after a re-start)....

[Mandrake]

I am in the process of relaying the headlights on the Xantia. Done the NS but ran out of cable and spades to finish the OS. Much brighter I will also double up the earths I think while I am at it.

I think I need to do mine one day - driving in the dark and wet on an unlit country road the other day I realised that my dip beam headlights are pretty poor and I couldn't really see that far ahead... They seem to point a bit low to me, at least while cruising, but they couldn't really be aimed up much more as they tilt up so much under heavy acceleration...

Did you measure before/after voltage at the bulb plug to see what the difference in voltage is ?

I've got change over relays (because they were available cheap!) and I've currently wired it power onto the common pin 30, as this seems to my mind the std way to wire it up - this leaves one of the pins live all the time the relay is not energised (ie headlamps off). Just wondering if there is any reason I can overcome my in built thoughts and wire it the other way - power to 87a and feed out to lights on 30 - so the other pin is never live? My only thought is that this might cause burning on the relay contacts as it switches, but maybe I am being over cautious - it is a 40A relay only handling about 5A after all!

I don't really understand your concern about reversing 87a and 30 - you're only reversing the current flow across the contacts - they're not polarity sensitive and won't burn out any faster with opposite polarity! If you don't like pin 87 being live when the lights are off, by all means reverse the wiring to 87a and 30. Nothing wrong with that.

[Old-Guy]

Probably put off the Xantia rear ABS sensor change for now - the light is only intermittent at the moment (although it is becoming more frequent and a couple of times has failed to go out after a re-start)....

Are you sure it's not the plug/socket contacts on the ABS ECU? In my limited experience (3 Xantiae) 'faulty sensors' have always proved to be dirty plug/socket contacts; cleaning and properly seating the plug/socket contacts is 100 times easier than changing a rear sensor!

[RichardW]

Simon - no didn't check the voltage, I'll do it on the OS if I can. I'll swap the connections on the relay - didn't really think there was anything in in, but just a nagging doubt!


Guy - Lexia has fingered the OSR sensor - and that is the one that the cable got a good mauling on when I removed the arm to repair the strut, and it only started after that - seems a bit much of a coincidence! Will have a look at the connector and ECU nonetheless, thanks!

[wheeler]

Are you just worried there is a live pin sticking out ?
If so just either pop a bit of heatshrink over the pin or an empty insulated spade terminal. Even better (and neater) use a proper relay holder base.