My 1980 XJ650 Project - Not Easy

Per the headlight, it was working the other night but then it turned off somewhere in the process of having it up on the lift tuning the carbs. I took it for a ride and the light came on after hitting a pothole. Then it turned off again after hitting another bump. I tried simulating another bump and even checked fuses to see if it had blown. The original fuses and fuse block seems fine and the old connectors are not fractured or damaged. But I haven't broken out the multimeter as I don't have much experience using one, other than battery voltage readings. I checked again to see if the light would turn on after everything cooled down but still nothing. All other electrical components working aside from headlight and guages display light. Neutral light comes on too. Please help!

 

For the headlight, there is a relay for it under the left side cover below the TCI and regulator. I would check those connections and the relay itself.

 

If your headlight still isn't working just scrap it and put in dual headlight relays. You'll have brighter lights and you'd be done by now.

 

So pretend I'm a child and don't know anything about relays and how to "check the connections" or test the relay or even what it looks like, how would you explain the procedure... to myself the pretend know-nothing child?

 

It's this guy circled below. Try unplugging and cleaning the contacts with some contact cleaner. It comes in spray form at the auto parts store.

You should do the same with the actual headlight connection in the bucket too.

I'll have to look at the wiring diagram later to give you the details on testing it etc.

 

There's really only a couple things in play. You said the gauge lights go off too? That would indicate something wrong with the fuse or relay/relay connection then. Since it appears to happen when you hit a bump and you have the original fuse block, I would suspect that first.

See below, power goes from the fuse to the relay, and then to the dimmerswitch and gauge lights. Since the gauge lights go off at the same time, I would think that the switch and light is fine.

 

Your relay *may* be under the tank. The manual for a 1980 G bike says that it's under the tank, but the cabling picture shows it where my picture does.

 

Thanks guys, the rain has finally stopped so I can look into these solutions today. I'll check the relay and headlight connections and test the headlight to see if power is getting to it. How do you test the relay?

Is it true that due to the headlight relay the light shouldn't come on until the bike is started? I'm pretty sure the light was coming on once key was turned to the "on" position. But I've been wrong before... 1997 I think it was.

 

On yours, the headlight will be on until you hit the starter button, then it will turn off until the engine starts, then it will come on again.

 

You sure? Looking at the diagram, the relay would be open until voltage from the charging circuit energizes the relay. After it closes, there is power fed from the NO terminal on the relay through a diode back to the coil on the relay to "latch" it on until the key is turned off.

 

What jay said...Headlight is latched on when starter spins, off with key turn.

Gary H.

 

I'm sure that I might be thinking of a different model when I was thinking that.

 

Ok, so here's what I found... Multimetered out the fuse connectors for the headlight and getting over 12V. (However fuse holder clips broke in two pieces upon inspection of the glass fuse). Even when the fuse was installed and before I broke it apart I wasn't getting anything (zero volts) directly at the headlight connection. There's no power to the headlight connection inside the lamp housing.

What now? Besides getting a new fuse box. There's something else stopping the flow to the headlight.

 

You are going to want to upgrade the fuse block. The original one has the cheapest crappy fuse clips ever manufactured on the planet.
xj4ever has new fuse blocks with extention wire kits that makes the job easy and professional looking. Plus the push in blade style fuses are available at any auto parts stores.

 

+1 on upgrading to a new fuse box. The kit from Len (XJ4Ever) is nice. It's an upgrade that will eliminate some problems, present and future.

 

Yep. Brittle fuse clips, the most common electrical problem in bikes of the era. Either upgrade as mentioned, or replace with new clips.

 

But I still should get power to the light even if the fuse wires are jumped/connected w a small wire correct? What should I check next?

 

Technically you should but bypassing fuses is risky, if you have a short your harness is goin bye bye.
Make a jumper wire up with a fuse in it so if something goes wrong you will be covered.
Obviously the common terminal on the headlight goes to ground (check ohms to ground on the frame) and your power has to come through the high/low beam switch. Clip one lead from your meter on common and pick back through your harness to the switch. See if the switch is bad or is the problem before the switch.

 

Thanks guys! MN-Maxims, I will do as you suggested and see if I can find anything today. Silly question, does motor have to be running when testing, or since I'm using Ohm setting, just test with engine off and Key on? Still confused about the relay and when it opens/closes and actually sends power to the light. I don't want to be testing incorrectly and wasting my time or chasing my tail.

 

You will only have power to the headlight once the motor has started or at least spun fast enough to send enough voltage to latch the relay. You need to check for 12 volts at the fuseblock, then at the relay. If the diagram above is correct, it should be the R/Y wire. If you have 12 volts there with the key on and not running, then start it and see if you have 12 volts at the L/B wire coming off the relay. If that's good, then you have an issue upstream between the relay and headlight.

Do the gauge lights light up with key on or after starting?