Need assistance tracing down short

[joltman]

I am brand new to the forum. I've inherited a 1993 Nighthawk 750 from the father-in-law (FIL). I've had it since May 2012. It's been fun driving to work and back. I have had some issues with the turn signal switch not always turning on, and sometimes it hasn't turned off when I pressed "inwards". It used to take a firm push inwards to turn it off.

Last summer, it didn't get a lot of use. I had it in a "garage" (more a building with holes) and that seemed to keep it mostly protected. I was forced to tear down that garage when I was selling my house. So the bike sat outside for over a month. When I finally got back on it, I was heading to the gas station. I turned on my blinker and then all the lights stopped working on the bike. It then just stopped. I found that the fuse for the lights/neutral was blown (15A). I replaced the fuse with a new 15A. Luckily, I wasn't too far from home, so the wife went to get my Tahoe to jump the bike. I had the Tahoe off and on (which I just learned is bad). The bike would start while jumpered to the 'Hoe. When the bike was running, I tried the turn signal again. Another blown fuse. Eventually, the bike let out an enormous POP! It wouldn't start after that. I had to push the bike back to home. When I got there, I found that the battery was low on water. I went to fill it up, and water was leaking from a crack in the side of the battery. That is most likely what caused the pop.

Fast forward to today. Wife and I have moved from IL to Denver and brought our bikes with us. Obviously, mine isn't running. Today I went to Interstate Battery to pickup a new battery (AGM). I brought it home and popped it in the bike with a brand new 15A fuse. Guess what!? I was able to use the left blinker no problem (heard the blinker clicking noise as well). When I tried the right blinker, the blinking noise was faster and the right lights weren't blinking. However, the brake and headlights seemed to dim to the sound of the blinker clicking noise. Then the fuse blew. Crap.

Luckily, the FIL gave me a Clymer Service/Repair/Maintenance manual for this bike! I was checking the electrical troubleshooting area. The instructions told me to take off the neg lead to the battery and take out the bad fuse (which doesn't really matter). Then, to take out the headlight and trace the wire bundle from the turn signal switch on the left handle to the headlight housing. It told me to test the continuity between 4 pairs of wires using a multimeter. Below are my results:

	Switch Harness-Lights	Right Switch	Left Switch	Switch Off
R	Gray-SkyBlue	.5 Ohm	2.3 Ohms	Infinity
R	Black/Brown-Skyblue/White	5.7-5.1 Ohms	.9-.2 Ohms	.6 Ohms
L	Gray-Orange	2.8-2.1 Ohms	.7-.3 Ohms	Infinity
L	Black/Brown-Orange/White	.5 Ohms	5.8-5.3 Ohms *	1-.7 Ohms

* This went up to over 8 Ohms on a few occasions

This table shows the connections I made from the switch side of the harness in the headlight assembly to the actual front turn signal lights. I used my multimeter and the ohms are shown in the table. I have no idea if this is even normal. How do I know what I should be getting? The book just tells me this:

Right	Gray-Skyblue	Black/Brown-Skyblue/White
None/Off		Black/Brown-Orange/White-Skyblue/White
Left	Gray-Orange	Black/Brown-Orange/White

The dashes indicate where there should be "continuity". I took that to mean a "closed circuit". So I had one lead of my multimeter on Gray, the other on Skyblue. Then I hit the right turn switch, then off, then left turn switch. I did that several times too. The switch wasn't smooth to move either. It would also take maybe a push or two to turn off.

Can anyone help me? I hope I've provided good information. Thanks!

 

[joltman]

I wonder if a bad light bulb could be causing this?

 

[sunfish]

I'm suspicious of the switch itself, especially if it's hard to move. It sounds like there is a short somewhere and it would seem strange that the switch would be blowing fuses like that but I think it could. Check the physical condition of the wiring, if they are shorted it would likely be due to damage and you might be able to find it just by looking. Also you could be right about the bulb, although I have my doubts. That would be strange for a bulb to be shorted like that but if It were it could give you problems. I'm in Denver also if you need some help.

 

[joltman]

Still Stumped

I'm suspicious of the switch itself, especially if it's hard to move. It sounds like there is a short somewhere and it would seem strange that the switch would be blowing fuses like that but I think it could. Check the physical condition of the wiring, if they are shorted it would likely be due to damage and you might be able to find it just by looking. Also you could be right about the bulb, although I have my doubts. That would be strange for a bulb to be shorted like that but if It were it could give you problems. I'm in Denver also if you need some help.

Sunfish,

Thanks for your reply. I've been quite busy the past few weeks and haven't had a chance to get back to the bike until just now. I've checked the right signal light bulbs. They're not blown, and they're not corroded. I didn't put a multimeter to each bulb, but normally, you'd be able to see if the filament was burnt out.

You mention to check the physical condition of the wiring. I don't want to sound stupid, but where should I be checking? Should I be taking the wrapping off the wire bundles to check the physical insulation of each wire? Wouldn't that entail removing the tank and other components? Or am I getting way too wrapped up in details? Should I be checking each wire for continuity between certain points? As you can probably tell, I'm not an automobile electrical expert . I'd appreciate any advice. Thanks!

 

[sunfish]

joltman,
after rereading your original post it sounds like a slightly bigger issue than I originally was thinking. when I said to check the physical condition I meant to check for wires that had gotten pinched or otherwise damaged. the wires that go under the tank and other hard to reach places are pretty well protected and the chances are less that they are damaged in those areas. that doesn't mean that they can't be but you can probably put that off until you've eliminated other things.
I don't think I would call myself a wiring expert but that is a big part of my job (if you know anyone in the Denver area that needs to pass a breathalyzer test to start their car, there's a good chance I may also know them). just the same, I'm having trouble visualizing the circuit. In your manual do they give specs as for as what you should be reading for the continuity checks that you did? If I get a chance this afternoon I'll look over the signal circuit on my own bike, which should be somewhat similar, and see if I can wrap my head around this.
I've taken a sort break form cb750.com but now I'm watching again so I should respond faster next time. Hope you get that thing running soon, the weather is getting nice.

 

[sunfish]

okay, that didn't take long at all. after seeing what you were testing I've got a little bit clearer picture. these tests are meant to test the switch itself. the switch is basically supposed to have two possible readings, on and off. most of your readings are somewhere in between. I did all the same checks (my black/brown wire is a different color) and got drastically different results. all the readings I got were either zero or infinity. unless you see damage to the wires between the switch and the plug inside the headlight housing, I've got a strong feeling that there is a problem with your turn signal switch.
does the bike run? While you didn't say it, I got the impression that that was fixed with the new battery.

 

[joltman]

sunfish,

Thanks for taking the time to help out a newbie! I haven't tried starting the bike yet. I have a feeling it will start, but I wanted the turn signals to work before I started again. I know I could use hand signals for when I turn. That or always turn left!

Thanks for testing your switch. Did you completely unplug the wires that are in the headlight bucket that run to the switch? I left everything connected in there and just jammed my test leads into the clear plastic sheath to test. Even doing it the way I did, I would think I should get the readings you did. 0 or infinity. Maybe I should take the switch off and clean it.

 

[sunfish]

you definitely want to unplug the switch to test it, otherwise you're reading from light bulbs and everything else on the other side of the circuit. If the switch is just corroded from exposure to moisture you might be able to get a little more life out of it if you can take it apart enough to clean the contacts inside of it. otherwise a new (or used) one shouldn't be too hard to track down and should be easy to install. I see some on ebay right now for between $25 and $50. test again with the switch unplugged before you do that.

 

[joltman]

Sunfish,

I've finally had the chance to remove the turn signal housing from the bike. It was actually easier than I had thought it would be. Everything is color coded under the headlamp and will be easy enough to put back together. I've taken some pictures along with a video that shows an example of what I'm seeing. Its pretty obvious that the switch has seen better days. Tomorrow, I'll take apart the switch and clean it with sand paper/cleaner and hope that the numbers get better. Here's a link to the pix and video.

Here are the new resistance measurements now that the switch has been removed from the bike:

	Switch Harness-Lights	Right Switch	Left Switch	Switch Off
R	Gray-SkyBlue	4 Ohm	Infinity	Infinity
R	Black/Brown-Skyblue/White	Infinity	2 Ohms	2 Ohms
L	Gray-Orange	Infinity	2.8 Ohms	Infinity
L	Black/Brown-Orange/White	2 Ohms	Infinity	2.2 Ohms

 

[sunfish]

Progress. That is one cruddy switch. If it were me I'd replace it but if I were honest I'd admit that I'd probably try to clean it first. My guess is that you can get it to work if you can clean it and get it back together fairly easily without breaking anything.

 

[joltman]

So, I took the switch apart and cleaned it. It was very simple. The contacts didn't look bad at all. Here are some photos. I'm thinking this is not a switch issue. I guess the next step is to try replacing the relay.

Also, I discovered the bike won't start. It just clicks. I have a brand new battery that's been on a Battery Tender since I got it a month ago. I'm almost thinking I should call a shop to come get the bike and fix it for me. This is getting frustrating.

 

[sunfish]

The contacts don't look all that bad but have you tried testing the wires like you did before now that you have cleaned it up? The offer still stands if you want me to look at it. we are in the same city and I do well with electrical. no pressure, just offering.
Not starting, that's a whole new problem. could be any number of things. If it's clicking it sounds like the solenoid is working (that's the issue I occasionally have with mine. eventually I'll get around to replacing it).