Headlight/dash always on, bike can run without key

First: apologies for length. I've been accused of being verbose in the past.

I have an '82 750 Maxim, and out of the blue, the keyswitch stopped turning off the engine. I found this out when I stopped for gas the other night: pulled up to the pump, turned the key to off, pulled the key out, and as I was opening the gascap realized ... the bike's still running.

Initially I thought my keyswitch was faulty (Follow along all the great advice I got when I was looking for its replacement in this thread). It had become kind of cranky when I tried to lock the forks, so I figured it could all be related. I wound up ordering an Emgo 40-71340 switch because it was stupid cheap ($20). [Note: It's not a direct replacement; you have to swap the locking bases, but otherwise it works fine. If your fork lock is broken, don't order this]. Unfortunately, this was not the fix I needed. Upshot is, after cleaning up the fork lock, that works nice & smooth again.

So my situation: regardless of the key location (park/lock/off/on/in my pocket) the headlight and dashboard have power, and I can start the bike and it runs. The kill switch on the right switchgear still functions properly. However, I noticed the brake light only has power when the keyswitch is in the 'on' position - that's SOP, at least. So this tells me there's something crossed up somewhere in the harness.

I'm still riding the bike; when I park it, I kill the engine with the right-hand button, lock the forks, pop the seat and pocket the main fuse. Kind of a nuisance (but it is definitely immobilized).

Of note: the fuse box was swapped for a common buss blade-type unit from XJ4ever sometime last year. This was my Dad's bike that he never rode; he did the fuse box update (He was going to sell the bike, so I adopted it.) He's anal-retentive, so it's a very nice, clean install. That doesn't mean he didn't overlook something though; prior to Monday, it's been fine. I don't think it got any miles after the fuse box update was done until I started riding it (if I had to guess, I'd say I put on 200-300 miles before this started), so I'm of the mind that something has become pinched thanks to N/V/H and is creating a short that's only affecting the front of house (headlamp/dash/ignition).

So my question to you, Gods-of-all-Things-XJ, wise and all-knowing ... any ideas where to start? I feel like something to do with the new fusebox is the culprit, since that's the only thing that has changed lately. Not saying it's the fusebox itself - most likely something in the install - but I wonder if anyone knows a particular section of wiring that I start with. Something that allows the headlight/dash/ignition to get power - but not the taillight.

Thanks in advance

 

Can you provide a pic of the fusebox - I don't think XJ4ever sells a common buss type.

 

I believe I mis-spoke; I guess it's an ATO/ATC style box. I don't have a picture at the moment, but I can snap one shortly. However, it looks quite similar to the one in this write-up (which is most likely the write-up my Dad followed; he even angled the spades on one side to make it fit, but specifically cited XJ4ever as the source) - only he bought a 6-slot unit, to carry a spare.

 

Is that the brake light or the tail light? Are the flashers and horn disabled with the key off? The tail light uses a separate switch contact and is not common with the other circuits on the output of the ignition switch.

And N/V/H would be?

Since it did work for a while that would imply a short in the main harness since you replaced the switch. That could easily be checked with a DMM. Note also a miss-wire could cause a similar situation (except for why it worked for a while). Check the main fuse wiring just to be sure the input is a large Red wire with no tracer and output is a large Red wire with no tracer.

 

agh, caught me up again. The tail light is off, until I turn the key to on. But that makes sense if the taillight is on a different circuit than the front of the bike. I did not check the horn & flashers. I'll get back to you on that one.

Noise, Vibration & Harshness. The stuff that makes bolts shake themselves free and wires rub together in unfortunate ways that you won't see when it's sitting on its center stand.

Yeah, I'm at loss why it worked like normal, then stopped. Nothing happened to indicate the failure occurred; it was fine ... until it wasn't. Makes me think something exposed a short while it was being ridden. I'm going to sniff around the new fuse box this weekend. Fingers crossed that it's glaringly obvious and I was just looking in the wrong place.

What's a DMM? A multi-meter?

Also. Thanks for humoring me with all the back & forth. Diagnosing electric gremlins isn't much fun in person, nevermind remotely, over the Internet. Your input is greatly appreciated!

 

one of them fancy new-fangled digital ones.

 

Totally agree and have often wished I could be looking over the shoulder during the diagnostic process.

Hopefully, you will find an easy repair.