Electrical woes... or, "Hotwiring in Mexico".

So I will copy and paste from my trip thread the relevant portion, but my original writing was perhaps a bit longer than it had to be. So if you'd like the short version, skip the quoted text immediately below.

Short version: Bike died suddenly when I pulled over to fill up for gas. No lights. Saw this briefly earlier on the road, but a tap to the battery seemed to fix it. When I say 'died', I mean total electrical failure: no lights anywhere, key and switches do nothing. I eventually realize I'm not getting power to any fuse except the main fuse (all fuses are good, battery is good). I pull the wires going to the 'head' fuse and connect them into the leads for the 'main' fuse, and boom, hotwired bike, runs fine. I drive it for 3 hours to get where I'm going, pull over, and pull the wire. Now I'm trying to fix it.

In my travel thread (see signature), I was directed to this thread: http://xjbikes.com/Forums/viewtopic/t=1 ... vious.html

So, going through the steps, the first few are all good, until:

I am using a multimeter as my continuity tester, and I'm an electronics novice, but I put it to ohms, to 200 (the lowest setting). This is a cheap-o harbor-freight multimeter, so the 'infinite' setting (open circuit) just looks like a 1. When I put the two leads from the multimeter onto, say, the exhaust pipe, I see numbers from 40/50 to 150 pop up sporadically.

Using the same settings, I put the negative lead onto the battery and the positive into the blue-white side of the plug. Infinite. Press the starter button. Still infinite, no activity on the screen.

Thing is, I know it's not just the starter button, since I don't see ANY LIGHTS. Starter button won't do that. I very well may have starter button problems, though, since it was replaced in the past by some PO, and it did get jammed 'on' at the beginning of the trip once and I had to un-jam it. But I don't think that's the problem... When the starter button is jammed on and the bike is running, it just makes the 'check oil' light come on, doesn't kill the bike.

Just to verify, I have the two wires that plug into my multimeter; there are three holes on the multimeter, however. I know they work in their current order (negative into "10A DC (10a max)" and positive in "VΩmA") for testing voltage, and act as described when touching to a piece of metal with obvious continuity. The third hole is labelled "COM" which appears, to me, to be for high voltage given the other words around it, though I don't know anything.

So I went ahead and tried the next one:

Didn't see anything for this test either. No 12 volts. Picked up kickstand and held in clutch, in neutral. But can someone tell me where the starter circuit cut-off relay is?

Also, if I have to guess, based on all this reading, writing, and testing, I'm guessing that maybe... there's a short between the ignition key input and the main fuse?

 

The starter circuit cut-off relay is behind the left side cover just below the TCI. According to what I have read, it might be the clutch or neutral safety switches. However, on my 82 750, when I pulled this relay (because mine was getting no power) the bike came alive.

 

given your symptoms my first test would be to pull the 3 prong plug from the key switch and test the continuity on the key side between the red and brown wire with the switch off then on and see if the switch is functioning properly. Then test on the bike side the red wire back to the main fuse and the brown wire back to the other fuses.

 

fintip,

I found a wire diagram for an 82 and i think it may be the same with the exception of the electronic tach vs cable driven tach.

If I read what you did to get your bike going correctly you jumperd the main fuse to one of the other fuses. This in essance bypassed the ignition switch. Here is what you do to see if thats the problem.

Set your meter up to read volts
Place the black lead on the neg battery terminal
check the red lead on the battery pos post to make sure you have 12 volts. Reads ok you have good connections.

Ok inside your headlight find the connector for the ignition switch.
put your red lead on the large red wire and you should have 12 volts
Then turn the key swich on and check for power on the brown wire you should have 12 volts. That is the wire that feeds the other three fuses in your fuse box
Lastly there is a blue wire. check for voltage on that wire. you should have 12 volts.
If you have power on all three with the switch turned on your key switch would be OK. If not you are going to need a new switch.

MN

Hope that helps

 

Mook, are you saying that taking the relay by the TCI out solved your problems? (Were they similar to mine?)

Thing is, I was reading the input right before the keyswitch, and not seeing any voltage there. I will check again though and get back to you guys.

Assuming I have voltage going into the switch, then yes, I would assume that the key was the problem. (I did transplant the key switch over from the last one, so I might have shaken things up or pulled on wires too hard somewhere, so there's some credence to that theory... Though I would think jostling those wires around should have seen the lights at least blinking on and off intermittently if that was the case.)

And yes, MN, realizing that I wasn't getting voltage to the keyswitch or that it wasn't working, either way, I decided I had to bypass it. So I powered the "head" fuse off of the "main" fuse line, skipping the keyswitch circuit altogether.

I've got 12.8 volts tonight, btw.

Only thing I don't understand in your instruction, MN, is how I could see 12v while having the plug pulled apart so that I can get a reading from them? I don't have it apart in front of me right now, so maybe I'm missing something, by just to confirm: are you giving the same procedure as maverick, or something else?

 

Dont pull the plugs apart just probe the back of the connectors where thay crimp inside the plastic plugs. Just look inside where the wire goes intot he plugs you can see the brass crimp around the wire and your probe on your meter lead should reach it.

MN

Just as a side note that big red wire comes right from the main fuse in your fuse box. The other side of that fuse goes back to a big ring terminal on the starter solenoid under that battery cable.

 

No, it didn't solve my electrical problems. What it did was help to pinpoint what it was....and allowed me to crank and run the bike while repairing the sidestand switch that was corroded on mine. Being that it is a really easy check to pull the cover, unplug the relay, and check for power and if the bike will fire, then only wastes time if it isn't the issue. But from what I was reading in the manual. that is actual part of the starting system tests. According to the manual on your model.....

"The above models employ a simplified starter interlock system in which the engine may only be started if the gearbox is in neutral or, if the clutch lever is pulled in. When the ignition and engine kill switches are turned on, power is supplied to one contact of the starting circuit cut-off relay. This component remains off until its windings are earthed through the neutral switch or the clutch switch. Once ether switch closes, the relay circuit is completed and the relay contacts close. Power is fed through the relay to the starter relay (solenoid) and the engine can be started by pressing the starter switch."

So out of this, assuming the wiring to the fuse box is good (mine was corroded about 1/2" inside the insulation, and the fuse box and fuses are good, the power goes from the battery, to the kill switch, to the ignition switch, to the above mentioned relay. So seems to me, the focus should be on your kill switch, then your ignition switch, then down the rest of the path.

The red and white wire from the kill switch is what you will need to check to see if it has power from the battery. If not, then it is between the battery and the kill switch. If is has power, then check ignition switch.

 

Oh!!!no, no wait! I was mis reading. I thought you lost power to the engine, not the whole bike. In that case, there is only 1 wire that goes from the battery (red wire) to the ignition switch. If you had to jump power from the main fuse to the head fuse, then it is your ignition switch. Power simply goes from the battery, to the main fuse, and then from the main fuse (while splitting off to the rectifier), to the ignition , and then back on to the fuse box and the rest of the circuits. Since you can jump the main to the head, and the bike runs, Then your issue is either the ignition switch, or in the red wire between the split to the rectifier and the ignition switch.

 

OK, MN, that's all super useful, and now I read your instructions and feel like I really get it. To clarify:

That red wire is the input from the battery, obviously. Brown wire is output, and should only show voltage when the key is in the 'on' position. Is the third plug the ground, and the place I should put my black/negative lead? (You only mentioned where to put the red.)

And what is the blue wire? Or, is the blue wire the third one on the keyswitch plug? In which case... What should I use for negative? The engine or handlebars?

Mook, you seem to basically be confirming what MN said, but... The rectifier connects AFTER the main fuse? Really? How does that make sense? I mean, the rectifier is the finned unit on the left side where all of the voltage coming off the crankshaft is turned into 12 volts and the excess is let off as heat--from it, power goes to the battery. Are you saying it goes backwards through that MAIN fuse, through the solenoid, into the battery? But as well going straight to the keyswitch and so forth on into the rest of the system, from right there? Just seems like a terrible design; if the regulator goes bad, it would start frying stuff, right? Or would it kill the 20A fuse first and prevent you from starting up (assuming you don't fry it before you stop the bike)...

 

Yes, just what MN said, and according to the diagram for your model bike, assuming you are riding the model described in your sig. The red wire goes from the battery, to the main fuse, then from the main fuse to the ignition switch with a split/splice/junction between the main fuse and the ignition switch that goes to the rectifier.

Well, I do not have a diagram of the rectifier yet, but I do know that one of it's functions is the regulate voltage. I did not say it goes backwards, only that there is a joint on the red wire from the main fuse to the ignition switch that goes to the rectifier. It is my assumption, that that wire simply provides voltage or a "hot" to the rectifier/regulator, so it can regulate the voltage to the associated components. By reading this schematic, that red wire to your rectifier should show hot, regardless if the ignition switch works or not. This design doesn't make good sense. But, by continuing to study the diagram, if the ignition switch works, the brown wire goes to the generator, then a green wire and 3 white wires then go to the rectifier. It is my assumption that one of those wire then control a switch that tells the rectifier to do its job with the voltage feed from the main red wire. However, this rectifier discussion is getting off topic, as in actuality, all power to the whole bike has to go through the ignition switch before it goes anywhere else. I still say you have a bad switch, bad connections to the switch, or bad wire from the main fuse to the ignition switch. If you have voltage at the main fuse, and then no voltage from the brown from the ignition with the key switch on, then check for voltage red wire before it goes into the switch. If you have power to and from the switch, then it gets hairy....

 

Oh, and BTW, the blue wire is the feed from the ignition switch to the tail light...

 

Fin tip,
I'll get back to my PC and I'll try to walk you through on checking this out

MN

 

Ok Mook is right the blue wire just goes back to the rear of the bike for tail light operation. So don't worry about that.

Ok set up your meter to read volts
Gound the black lead ( common ) to ground engine or chassis
Let's start with the positive lead from the battery to the starter solenoid. (just to make sure you have a good ground. )
Take your red lead from the meter and test the following points.
You should read 12volts
Now
The next stop the electricity goes is the battery side of your main fuse. Check there. 12 volts correct?
Now go to the other SidE of your main fuse and test there.
You should have 12 volts
Now the next stop
The big red wire in the connector to your key switch.
12 volts ?
The power goes through the switch and comes back out to the brown wire. Check the power on that output wire from the key switch.
Now if that is all good.
The brown wire feeds the other three fuses in your fuse box. Now it looks like there is a connector under the tank that that brown wire goes into. You'll need to locate it and see if the power makes it to that connector.
If you get 12 volts back that far you should have power at the power side of your fuse block, and all the lights and such should work.
Remember where ever you loose power in those connectors that's where your problem is. Between the last place you had power and the place where you don't.
I hope I'm not confusing you , if I am please let me know.

MN

Keep in mind the power has to come back to the fuse box before it goes anywhere else. The diagram I have shows this. The rectifier does not come into play until after all of this.
Or think of it this way , power from the battery goes through the main fuse to the key switch and then back to the fuse box. That's how you managed to bypass or hot wire the bike at the fuse box. Scary to think if someone wanted to rip your bike off with the steering unlocked all they would need to do is what you did and away they go. But of course they would need to get the seat off to do it.

 

No "connector under the tank" (as in "a plastic housing with a male and female side") where the single brown wire from the ignition switch is "split" into three separate wires that feed the HEAD, IGN, TURN circuits on the fusebox.......the brown wire is just physically split into 3 separate wires in a crimp or "solder ball" within the harness.......if you unwrap the main harness tape a few inches from where those three wires that feed the fusebox come out of the harness, you'll see the "split/splice/joint" thingy where the factory (kinda crappily) splits that one brown wire into the three separate wires.

 

Len you are correct. I could see some type of connector in the main harness but I assumed it was a plug in style connector. But I do believe that connection is in the harness somewhere under the tank. The only way to know for sure would be to open the harness up. I would not recommend that unless you really had to do that.

MN

 

Yep, no need to open the harness up! BTW, anytime you see, in the factory wiring diagrams, two (or more) intersecting wires with a round "dot" at their intersection, that "dot" is their indication of an in-harness splice point, which is either a solder ball or a metal ring that has been crimped shut around the bare wire ends that make up that internal splice.

ALMOST all "real" connectors are actually illustrated on the diagrams. Sometimes, the wiring colors and locations are even correct!

 

Ha! Those instructions worked well. And as I said, no voltage was getting TO the keyswitch (and what a random thing that would be to go bad, right?)

No, but the one thing I noticed right off the bat was MN's instruction to test not just the incoming voltage to the fuse, but the OUTGOING side. Behold, no voltage on the side of the fuse that goes to the key. The fuse looks fine. Must be the clips (this one has 3/4 old style fuses, but the fusebox looks well maintained and still has the original piece of paper indicating each fuse's function, so I didn't replace them. The head fuse was replaced with an inline fuse by the PO because it was having some kind of problem. Given that it still has a 10A blade fuse and works, it appears that the problem was indeed with whatever he replaced.).

So I go to find a spare piece of wire to put between the input/output wires touching the clips. I can't find one, and then... Ahha! Paperclip!

I run it across, and voila. Immediately works perfectly.

But just in case... I have some replacement glass fuses. I fish out a 20A and pop it in... BAM! Works.

Huh! So it was just a bad fuse. It's still intact, though. Must be some really old fuse? Anyways, I patched the HEAD inline fuse back up, put it all together... There was a moment where I had lights but no action when I pressed the starter button that stumped me and had me pulling it all apart again... But then I realized I had just left the solenoid 'plug' for the small wires unplugged.

All is well now!

Thanks for the help. I learned a lot regardless.

 

I've been stumped by fuses of all types that "look" good...and spent enough time chasing my tail on a bad assumption that I always test them in place, with a light or meter anymore before calling them good.

I saw some neat ATC fuses at the parts store that actually illuminate when they blow...thought that was a great idea but they aren't cheap...

 

Fin, good to hear it wasn't anything major, but it sounds like it is time to upgrade the fuse block and give all the harness connectors a tune up.

 

I've actually had a "glow when blow" blade fuse trick me. My headlight fuse blew, such that, when the bikes voltage was low, the headlight wouldn't come on. But when the alternator kicked in, it would light "just barely." I was having issues with my headlight relay at the time, and assumed it was the cause. Turned out that a glow when blow fuse just becomes a large series resistor when it blows (that's what makes it glow), which significantly reduces the current through it, and subsequently drops the voltage after it that the rest of the headlight circuit would see. But current can still pass through it, so you might get some voltage to the rest of the circuit. It won't do any damage, but it can frustrate your troubleshooting efforts.

 

Well there you go. Had to go through this once; while the fuse was my first assumption this time, next time I'll then presume that the fuse is lying. One more lesson paid for.

 

I got bit by that about 20 years ago when I was trying (and failing) to become a radio repair tech. Was doing a troubleshooting exercise on a seemingly dead unit. The main fuse looked good, but I had no power. Meter showed the fuse as an open -- probably near one of the metal end caps where you can't see the break.

 

My buddy lost power on the headlight circuit on his radian this spring, fuse looked fine until you pulled it and the metal end cap fell off.

 

It's great that it all worked out for you. This is a lesson and a possible warning to those who still trust your old fuse blocks and 30 year old fuses. Thank god fintip wasn't in need to throttle his bike to avoid an accident or have a truck run up his backside when he lost power. Upgrade your electrical before it becomes an issue. Good luck

MN