No dash lights or turn signals - possibly loose ground?

I have an '82 XJ750 Maxim that has been quite reliable until this morning. All regular maintenance has been done - shims, replacing the fuse box with in-line fuses, brakes, brake lines, etc. I took the bike for a 30-45 minute ride during a warm day over the winter without issues as well as to work one day in March without issues. Today it finally warmed up enough again for riding into work. Everything started find, all indicators on the dash flashed as the bike wen through the startup process and the headlight was bright. On the way in to work, the dash lights went out. If I put on a turn signal, the signal doesn't light up and the tac drops to zero. The same thing happens if I apply the brakes. The bike starts fine, by the way.

I checked the fuses when I arrived at the office but didn't find any issues. I checked the tail with the bike running and the running light is on, but doesn't get bright when I apply the brakes. I will look around the Internet for a wiring diagram and check the ground connects during lunch. I'll have to wait until I get it back home to check any connections with an ohm meter. Is there anything else folks recommend I should be looking at to resolve this problem?

Thanks for any advice.

 

As a follow-up, I found this thread - http://www.xjbikes.com/forums/threads/running-lights-and-dashlight-out.28307/#post-240515 - is quite similar so I will also be checking the wires in the headlight bucket when I get home tonight.

It seems that a faulty ground would impact all the lights, so this one may be more likely.

 

Additional information ... I used my lunch time to check the connections. I turned the bike on, without starting it, and the dash lit up. It looks like it is an issue with a component getting warm after the bike is started. I checked the connections and didn't find any issues. I'll have to blow up the wiring diagram and trace out the components, test each, and hope to find the source of the problem.

 

There are some push on wire leads in the headlight bucket it is easy to trace as wires are white/blue , yellow /blue etc check you connections .

 

It could be a high side or low side issue but either way it sounds like a poor connection (resistive) in the signal circuit that can no longer carry the required current associated with the brake or turn signals, which are both fairly high current.

What specifically are you referring to here? The instrument back lights (dash) are a separate circuit from signal, which seems to be where the problem is as noted by the tach not working when the turn signals or brake are activated. Only the neutral and indicator lights share the signal circuit. Are you having any issues with the CMS display?

 

The signal and the display both stop functioning when this problem occurs. The LEDs displaying fuel, neutral, kick stand, oil, etc. goes blank and the signals do not function. I keep thinking something is shorting out the electrical system, but I still get headlights and taillights. However, when I went back down to look at connections, all these functions were working again.

 

Did I mention that I hate intermittent problems? I just rode home with functional turn signals, a bright headlight, and a fully functional CRM display. The only indicator of a problem is a battery warning. I will get out the multimeter in the next couple days, hopefully sooner, to see if that is the issue. I left the battery in the bike this past winter, which is a first. Perhaps that was a mistake that will require a new battery.

 

Perhaps there was a poor connection there. I would inspect that area closely and just replace the signal fuse so if the problem comes back you know what it isn't.

Check electrolyte level if you are using the OEM battery sensor.

 

Thanks, I will do that. Fortunately there is no electrolyte sensor,. I switched to a sealed battery.

 

So did you add the resistor (6.2K) to create the voltage monitor?

 

The monitor at the battery was gone when I purchased the bike, a few years ago. I never had the battery light on the display come on, so I never actually checked. Perhaps I should do that this weekend.

 

It looks like I can call this one done. The issue ended up being a lose connection at the negative side of the battery. I assumed it would make the entire system fail, but evidently it allowed enough electrical flow to keep a couple pieces on, although not fully. One of the things I have found in life is that the more I know, the more I realize how much I don't know.

Thanks you for help in working through this problem.

 

I never say never with electrical issues, but that would be much more likely to present when the high current starter is activated. I guess you could speculate it was a bit intermittent, but then it would be hard to explain how the headlight would function, which is the highest current device on the bike next to the starter.

Any progress on the battery warning indicator?

 

The battery warning indicator went out as well. It is certainly odd, but I am not great when it comes to electrical issues. The bike also started right up this morning, but I don't know if that is due to the slightly warmer weather: low 50s instead of mid 40s. I certainly won't be taking it very far for a couple of weeks.