Hi guys and gals, I wonder if anyone can shed a little light(!) on this problem:

My grandparents have a 1997 Civic 1.5 LS which looks a lot like this:



It's a superb little motor, as I'm sure you all expect, except for one fault with the headlights.

The symptoms are that on startup the main beams are bright as they should be, but after a period (from about 10 mins to half an hour) the lights go dim - about three-quater strength and then right themselves some time later. This pattern contines throught the journey. Dipping and undipping the lights doesn't reset them but turning the ignition off/on does. I've driven the car and can't detect any relay-type clicking when they dim and it's not consistent with engine speed or load on the electrics as far as I can tell. The alternator belt isn't slipping and I can't work out what could be causing it.

Any Ideas? - Cheers for your replies, I'm pretty handy with a spanner, havig rebuilt my Maestro and kept my XJ-S on the road for some time so I'm ready to start taking stuff apart!

 

To me its sound like your alternator is weak, thus eating on the battery causing it to (after awhile) drain the batter y to whereas there is loss of power.

 

Basically what I mean is that a you or your grandparents need to go alternator shopping.
Btw, welcome to the forum.

 

could be a lose or bad ground wire

 

easiest way to tell is to get to a autozone or advance auto parts and let them run a test on the alt. and the battery...hope its not your alt....mine just went out and priced a new one for $170...but I got lucky...got one off of eBay for $20

 

Thanks for the suggestions, folks.

I had kind of discounted the alternator because the dimming wasn't a gradual fade, but rather like a relay or switch is dimming the lights. I suppose it could be due to lack of current from the alternator though. I suppose it wouldn't be too difficult to stick a multimeter across the output and see if it's reading any thing like 12-14v. I had kind of disregarded a poor earth connection for the same reason: I can't see how a poor earth would dim the lights uniformly and then'reconnect' them some time later. It sertainly wouldn't hurt to clean the earth points, wherever they are. I guess I'lll find some at the front of the car.

If you have any other ideas that I can try out please let me know and meantime I'll check that alternator.

Cheers

Simon R.

 

You would be utterly AMAZED what a bad ground can do sometimes.

 

I'll get me spanners...!