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Discussion Starter #1 (Edited)
Hi guys,

I have this wierd problem with the high beams on my s2 1750. When I hit a bump with the low beams on it often turns the high beams on. The stalk doesn't move, so I assumed it was something internal. The only way I can turn them off is to whack the steering wheel or the column stalk until they turn off again.

So, I assumed there was a broken bit of metal in the switch jiggling about or something. I needed to use my car one night, so I decided to cut the high beam wire (the thick yellow one) where it comes out of the column switch. I also bent it out of the way of anything it could earth on. I turned on the low beams, and they worked, then I moved the stalk down into the high beam position and they didn't come on. "Great" I thought. I pulled out of my driveway happy with my temporary fix and the bloody high beams came on again and blinded yet another motorist!

Why are they still coming on!? I'm not very experienced with electrics, but the obvious answer seems to be that they are shorting/earthing somewhere else, like the fuse box or the relays (I have aftermarket relays under the glovebox btw). The problem with this conclusion is that the only way to turn the high beams off is to whack the steering wheel or the column stalk. No ammount of abuse to the area around the fusebox or the relays has any affect.

Anyway, It looks like I'm going to have to borrow a multimeter and do some novice detective work, but if anyone could help me with any insight it would be muchly apreciated.

Sorry about making you read such a long post too,

Phil
 

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Was the wire you cut taking power up to the switch or from the switch to the relay? (Sorry I dont have a 1750 wiring diagram to check colours).

If it was taking power up to the switch then a short inside the column coulkd still turn the relay on, but the switch wouldn't turn 'em on.
 

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the obvious answer seems to be that they are shorting/earthing somewhere else, like the fuse box or the relays (I have aftermarket relays under the glovebox btw). The problem with this conclusion is that the only way to turn the high beams off is to whack the steering wheel or the column stalk. No amount of abuse to the area around the fusebox or the relays has any affect.
Well, that is pretty mysterious.

When you say "aftermarket relays", I assume that you mean a previous owner has installed relays in the headlight circuit. This is a good modification, as the original design had the headlight switch carrying all of the current, which would eventually destroy the contacts. However, the bad news is that you don't have a schematic showing how the relays were wired in.

It looks like I'm going to have to borrow a multimeter and do some novice detective work
Yup, it does. Since none of us know how that PO wired your headlight circuit, we certainly can't offer advice like: "oh, just clip the green wire at junction #23, and you'll be set".

However, one other diagnostic you might try: Are there two relays under the glovebox? If you disconnect the wires going to them one relay at a time, can you determine which controls the low beam, and which the high? If so, simply disconnecting the appropriate relay should disable the high beam circuit.

In the longer run, you need to figure out where that intermittant connection is happening, as well as repair that yellow wire you cut. And in the future, don't EVER cut any factory wires - most terminate with simple push-on connectors which can be easily disconnected and taped up for this sort of diagnostic work. Honest, some day a subsequent owner is going to be cursing you for that cut, just as you are now cursing the guy who installed those relays.
 

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I needed to use my car one night, so I decided to cut the high beam wire (the thick yellow one) where it comes out of the column switch.
If memory serves, the yellow wire is for parking/running lights; the high beam circuit is a gray (or green?) wire.

If you'd like a wiring diagram, minus the non-stock relays, please PM me your email address.
 

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Discussion Starter #5 (Edited)
Hi guys, Thanks for the speedy replies!

After reading papajam's post I realized I actually cut the green wire, sorry for any confusion. I went off a chart I found here which I've attached. Thanks papajam but I already have the wiring diagram.

Are there two relays under the glovebox?
Actually there are four. One for each headlight maybe? I'll try disconecting them, but surely a faulty connection there still doesn't explain why banging the column switch turns them on and off.

And in the future, don't EVER cut any factory wires - most terminate with simple push-on connectors which can be easily disconnected and taped up for this sort of diagnostic work.
Good idea. I only cut it because I was in a hurry and it was totally stuck on. I cut it right where it meets the connector so hopefully I can just strip the end and crimp it back on.

Thanks for the help guys, If I find anything out I'll keep you posted.
 

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