No lights

I went to start my bike and I have no headlight or instrument lights. My turn
signals work, my tail works. I have power at the fuse, but no power at the
headlight. Does anybody know where the two light inter connect. I'm thinking
a neutral? Please help I really don't want to start pulling wire harness apart.

 

I had the same problem. It wound up being a bad fuse. I have the original fuse box still and didn't find the problem until I used a test light across the fuse. Check for power on both sides of the fuse. I wound up pulling the headlight out and checking the connections at the bulb first, then the fuse. bassackwards way to do it.

 

I checked the power on both sides of the fuse 12 volts

 

There is also a headlight relay, though that shouldn't affect the instrument cluster, and some bikes have a diode block inside the headlight shell that should also be checked.

Have you tried putting 12V directly across the light to make sure it works?

I think the most likely thing is a bad ground wire somewhere. Time to start the continuity checks in the wiring harness. Bleh.

 

I know. I'll pull the tank tonight (Just filled it to) and start looking

 

On at least some of the models the cluster lights come on with the headlight after there is alternator output.

If they don't come on with it running check and make sure you have charging voltage.

 

We picked up an 83 XJ750 Seca for my wife. We managed to get it running (it sat idle for over a year) and replaced the clutch cable. All the lights seem to work except for the headlight and auxiliary headlight. We get 4 volts at the headlight connector, but 12 volts at both sides of the headlight fuse. The previous owner says that he had this problem fixed 3 times.... is this a common problem with the XJ750? Any suggestions would be appreciated. Thanks

 

kersting, what model bike do you have? Having a full fuel tank shouldn't be a problem, other than the weight.

Krazy, 4V means that there is an 8V drop between the fuse and the light (duh), but what THAT means is that either something has been spliced in that creates a load (and hence the voltage drop) or you have some bad wiring. Did the PO mention *what* was fixed? That seems like an odd problem to keep occurring. Headlight relay, perhaps?

 

Some XJ modles have a headlight cutoff switch built into the starter button. The switch turns off the headlight when the bike is started. I found this after many hours of trouble shooting my headlight.
The contacts had coroded making the headlight not work, your situation sounds familiar.
Good luck

 

Okay, on that bike, you should have lights as soon as you turn on the ignition switch (e.g. even if you haven't started the bike).

I would start checking continuity to ground and checking the headlight relay.

 

If your Maxim headlight harness comes from the gauges...I would be looking at a loose connector TO the gauges.
Those gauges do like to wiggle loose

 

I had a similer problem earlier and got a lot of help to fix it. Check out this post

http://www.xjbikes.com/Forums/viewtopic/t=9096.html

 

Do we know if the headlight relay is the small one under the tank
held in place by the square rubber boot? looks like it's next to canceling
unit. I'm really leaning towards this. I have power going and nothing coming
out if I'm reading it right.

 

On a 650 the relay will not trip until the bike is running and the alternator is producing juice.

The four wires on the connector are:

White - trigger from alternator output
Red with Yellow stripe - hot from fuse
Black - Ground
Blue with Black stripe - output to lights

So, the Red/yellow wire should have +12V anytime the key is on.

The White wire comes from one phase of the alternator through a 1/2 wave rectifier. It will have no voltage on it unless the motorcycle is running. I've never checked the voltage on it but I suspect it will be below +12V when running.

So, unless you have voltage on that white wire your headlight and instrument lights aren't coming on.

As you do your diagnosis you need to be aware that the relay is "latched". Once it turns on it supplies voltage back to the white wire. This keeps the light from going off if the alternator fails or if you stall.

 

do you know if this relay is unplugged if it will keep the bike from running?
I just want to make sure I'm looking at the right relay cause the wires on the connector are different colors. I have a red/white, red/yellow, black, and
a blue/yellow. When I unplugged it the bike would not start

 

You've got the starting circuit cut off relay. That's the one that keeps you from starting it in gear, with the clutch out. full throttle, downhill toward a cliff. Removing it keeps it from starting.

I think (but not sure) the headlamp relay is below the TCI under the LH side cover.

You might find this link useful:

XJ Electrical diagrams

Did you check and make sure you have 14 or more volts at the battery at 2K RPM? If not, your alternator is not working and the headlight won't come on.

 

THANK YOU I found the right relay tapped on it I have lights. My manual showed the relay under the tank.
Time to start looking for one.
Thanks again to everybody who helped me. I've posted things on other
forums and never get a response or very veg descriptions. When ever I post
something here usually with in about 30 min I have several very useful tips
and a good direction to start looking.
Thanks again

 

I had the EXACT same problem for the last few weeks. The circuit board in my 82 Xj750 Seca had fried across a portion and i lost both lights....kinda. I had the same 4 volts at the light also. Luckily my father is an electrical wizard. We jumped some things and hooked the main light to a terminal on the instrument cluster. Then I just ripped the Aux light off (looks better that way in my opinion). Now the headlight comes on as soon as i turn the switch on. I only have 2 issues however. I do not have a high beam (easy fix if neccesary) and the headlight does not shut off whie i depress the start button. Hope this helps.

 

I know this post is very old but this information was my issue. After checking everything else and going half crazy trying to find the cause of no headlight or panel lights these contacts was the cause. Cleaned them up and everything came back on. Thanks!!! mlew!!

I have a 83 XJ750 Maxim.

 

Good to see posts from 8 years ago are still being read.

 

If only that happened more often. The first thing that I did after finding this site was to spend weeks reading archived posts.

 

I read every new post EVERY day no matter what the subject is. Plus I've gone back and read hundreds of old posts! I've learned so much! Now if I have a problem with my bike I'm like " hey, I think I know what's wrong"!