Power will not turn off - Help

Hi List;
When I turn the key to the off position the power will not turn off on my 85 Maxim X (XJ750XN). Here is what I have done:

1 - I tried a blow dryer on the ignition - the power still will not turn off.

2 - then I sprayed a little WD40 in the key hole and let it sit in the hot sun all afternoon - still would not turn off

3 - then I tried spraying electric contact cleaner in the key hole and let it sit in the sun all day today - still will not turn off.

4 - I pulled the fuse for the ignition (under the instrument panel). Fuse looked good. Swapped it out with a couple of different ones - still wouldn't turn off. It didn't matter if the ignition fuse was out or in place the power would not turn off.

Where do I look next? Is it the ignition? Is there another fuse to look at?

Thanks in advance for any advice / suggestions.

 

I gather that your bike has got very wet for some reason.
If water has got down into the ig-switch, you may have to take it apart to dry it out.

 

Yes - I never had any trouble with the switch in the past. I washed it late last Thursday. Started it up and let it run for a few minutes then put it in the shed where it stayed until Wednesday morning. It started a little rough yesterday morning but when it warmed up it ran fine. When I got to work I turned the key to off and the power stayed on. I had to pull a battery wire to kill the power.

 

right side controls, rocker switch, run/off, main fuse=no power anywhere
the electrical contacts in the ignition switch are separated from the key part
i don't think spray makes it down there, take it apart

 

wiz is right... you will need to pull the ignition switch assy.

to get yours off...

remove the 2 large retaining screws that are attached to the headlight bucket. NOT on the ring itself

once you pull the headlight, disconnect it and set it to the side.
in the bucket is a 10mm bolt. pull that.
remove the lower bucket retaining bolt/nut attached to the triple tree.
move the bucket over and you will see the 2 bolts holding it on. pull those and when you lift the switch out, you will see 3 wires running to the bucket. unhook the connector and pull the switch out.
there are 2 screws that hold the switch to the back of the rear casing. undo those and the disk will come out. dry that off and put on some dielectric grease. put it back together and it should work for ya.

 

Looks like I will be pulling the ignition switch tomorrow night. Thanks for the replies and thanks for the instructions Helmet. I'll post back what I find.

 

Agreed, you need to open up the switch.

Contact cleaner won't solve the problem. Your problem is something staying connected that shouldn't.

 

I pulled the ignition switch from the bike. When I unplugged the ignition switch from the wiring harness the power stayed on so it is not the ignition switch. Since I had the switch off anyway I pulled it apart and cleaned it. It was in good condition and dry. What do I do next? Can I assume there is a short in the plug on the wiring harness? I really don't want to start cutting wires. Can I use a meter to test the plug on the harness? What would I be looking for?

----------------------
1985 XJ750XN Maxim X

 

if the power stays on, there is a stuck relay downstream. I dont have the diagram for it or I would let you know what relay is sticking

 

What diagram do you need? I have the service manual from the XJCD. Here is the wiring diagram.

http://picasaweb.google.com/felixmcc/XJ ... 7352855810

 

From this wiring diagram, the only culprit (assuming you didn't swap any connectors around or jumper any wires together before the problem started) is the rectifier/regulator (2 on the diagram). That's the only place besides the ignition switch where Red (battery +12V) could get connected to Brown (switched ignition +12V). Try unplugging the rectifier/regulator and see if the problem goes away.

 

There is no way the regulator rectifier could be causing that problem. It has no moving parts, or anything to become stuck. And there is practically an entire wiring harness where those two wires can become shorted to each other. And of course disconnecting the regulator rectifier is going to make the problem go away. It would make any problem go away as the bike would no longer be getting any DC power at all.

 

OUCH ! never say never

 

Can you say "shorted rectifier"? It's not a moving part.. but, then again, most electronic parts aren't moving parts.

DC power for the bike, when it's not running, comes from the battery, not from the rectifier/regulator.

I look forward to hear the solution from the owner, once he finds it.

Paul

 

It is virtually impossible for the regulator rectifier to be shorted in the manner that you describe. If it had shorted the way you describe, the thing wouldn't work anymore, and he wouldn't have been able to ride to work on battery power alone, and then continue to be able to troubleshoot with that uncharged battery.

Not to mention, in order for the regulator/rectifer to have become hot enough to short those two channels together, it would have melted the wiring harness and probably the connector, as the R/R is designed to operate at a much higher temperature than the wires and connectors can handle.

There are several relays on these type bikes, they all have moving electronic parts.

 

I would say, no. Although it is arguably not well defined, electronic generally means devices without moving parts or devices that use active parts such as semi-conductors or vacuum tubes. I would say relays are electrical but not electronic.

Anyway, as I understand it, your theory is that the R and Br are shorted together somewhere in the harness. Mine is that one of the rectifier diodes in the rectifier/regulator itself is short (thus jumpering R to Br). I don't see why you think shorting out one of the rectifier diodes is so unlikely... it can happen pretty easily if someone hooks up a battery or jumper cables backwards.

There's also the third (and fourth) possibilities that we are both misunderstanding the issue described by the owner, or that the owner is not correctly describing what's happening.

Until he posts an update, we'll just have to wait and see.

Paul

 

Thanks for all the help.

The problem turned out to be a short in the ignition plug on the harness side between the red and the brown. The plug looked fine from the outside but the two were making contact inside the plug. I don't think they were actually touching, just close. I fixed the plug so that I now have insulation between the two connectors.

I tested the battery and got a reading of 16.8 volts disconnected from my bike.

I hooked the battery back up and fired up my bike. At 1200 rpm it was holding steady at 19.2 volts.

I pulled the battery and there was hardly any fluid left in it. I topped it up.

I went to pull the regulator and the plugs were all melted. I had to pry them apart with a screw driver.

Here are some photos:

http://picasaweb.google.com/felixmcc/RectiferPlug#

The plug on the wiring harness is a little worst.

I tested the rectifier and if I am doing it right it appears to be fried. The service manual (charging system - page 7-23) tells me I should be getting continuity from red to all three whites. I am getting a value of 1 on all ( no 0's).

So I guess I'm shopping for a rectifier / regulator tomorrow.

Regards;
Felix - 85 XJ750XN (Maxim X)

 

I would say we aren't exactly discussing solid state electronics on a 1980s motorcycle. On the type bike being discussed, there are electro-mechanical devices in play. Time and technology has advanced while the bike has not, so that is a moot point. It doesn't matter how you try to technically define it.

And I never posted a theory. I simply stated that your theory was not likely while offering feasible alternatives. Fact of the matter is, compromised wiring insulation, or sticking relays, or bad connections at other parts of the bike are for more likely to be the cause of the problem than a short in the R/R.

 

Does your meter have a zero feature? Your voltages sound correct respective to each other, just on the wrong scale.

Also, you have to do two different checks in order to properly test the both the regulator and the rectifier sides of the R/R. You should have little to no resistance between each of the white wires and the black wire, and again, little to no resistance between each of the white wires and the red wire. But when you swap the polarity of the test leads you should get high resistance between the same wires as before. On my bike, I get close to 300 ohms in one direction, and 0 in the other. In order to test the regulator side, you need to check both the brown and green wires while using black as the common. If you are truly getting 16 to 19 volts coming out of the green and black wire check, you do need a new R/R as the high reading should be between 14.4 and 14.8V at higher revs.

 

I am new to multi-meters. I am setting the meter to Ohms and using a setting of 20k. I am attaching the red lead to the red wire and the black lead to the white wire. Here are some photos:

http://picasaweb.google.com/felixmcc/Dr ... NjdpI2OBg#

I am getting a value on 1 on the meter. Shouldn't I be getting 0 for no resistance?

When I tested the volts while the bike was running I did it right on the battery terminals and received 19.2 volts at 1200 rpm's. Should I have tested it somewhere else?

 

The 1 is actually an I which stands for infinite resistance. That is what you want when checking for very low or no resistance. The sensitivity of your meter can determine your readings when checking for very low resistance.

At this point, If you are setting your meter to Volts and truly getting 19.2 volts, your R/R is defective and the resistance measurements I described earlier don't matter. Double check your meter by checking the voltage in one of your electrical power outlets. It should read about 120 V depending on the capabilities of your meter. If it is anywhere near that, I would say it is working properly and your 19.2V reading accurate.

 

Check out my project page... I understand these electrical systems quite well. Not only are we talking solid state, we are even talking computers in the 750 SECAs. The ignition system is completely solid state and somewhat integrated.

I also understand that there are relays used in this system, which are, as you say, electromechanical (not electronic) devices, but in this context that's somewhat irrelevant as, per the wiring diagram, there are only two places where Red and Brown come together, and neither of them is a relay.

Felix, if you are using a digital multimeter, which I expect you are, then you are reading WAY too high voltages, and you're likely correct that your rectifier/regulator is blown.

Cheers,
Paul

 

I'm not sure why you keep trying to drift off on tangents. The bike is not a Seca, it is a Maxim, and the drawing that was posted does in fact include a relay in the ignition system.

Just face it, the short as you described it had a very low likelihood of occurring, and it apparently was not the cause of the problem at hand. I'm not saying that the R/R wasn't the cause of the overheating that might have caused the problematic short in the first place, but it surely wasn't a short between the red and brown coming together in the R/R that was causing the bike to stay on. And if you continue to look at the diagram, you can see that there is more than one place that power could have been shorted to the ignition system. It doesn't have to have been between the red and brown wires.

 

Felixmcc :
maybe you better hold off on plugging that meter in a wall socket just yet
till you get the hang of it

 

Not to fire up any argument but I'll respectfully disagree DirtyMaxim. A relay (as used on our beloved XJs) is an electro-mechanical device. As such, there are no moving parts in the electronics, only mechanical solenoids (which is just another fancy word for a relay).
But you do have a point, there are no moving parts in the rectifier. This would tend to lend itself to your perspective of no parts getting stuck but I have seen for myself where diodes have burned through and transistors short (effectively a "stuck" component) leading to a shorted assembly that would allow current to ramp up and melt wires. That said, I too am curious as to the outcome of this electrical conumdrum. As I am unfamiliar with the X electrical system, I will defer to wiser men than I concerning this problem.

 

BDM, please point out how +12V will be continually supplied to the switched (Brown wires) side of the electrical harness if it's not coming from the battery (Red wires) part of the electrical harness.

Felix, since your regulator is probably currently disconnected, could you please take an Ohms reading between the wire or pin on it that connects to brown and the wire or pin on it that connects to red and let us know what you find? Or, if your meter has a Diode Check function, please try that, with the red probe on the red connection and the black probe on the brown one.

Thanks,
Paul

 

You said it yourself earlier. "shorted".

 

Where!?

You said "It doesn't have to have been between the red and brown wires." I'm saying it does.

 

Paul;
I'm getting an I when I do this test. I'm setting the multimeter to Ohms and choosing the 20 k setting. When I turn the meter on it shows a I and when I touch the pins the resistance does not change. If I flip it around and go red to brown and Black to red it still reads I.

Polock;
I opted to test the meter on a 9v camera battery.

 

Hi Felix,

When set to Ohms, if you touch the leads to each other, it should read less than 1 Ohm. If it still reads I, that would be a problem.

As for the Red or Black lead going to one pin or the other, this only makes a difference if the meter is set to Diode Check (if the meter has this mode). That mode might also be marked with a diode symbol (a line through a triangle with a vertical line next to it).

Cheers,
Paul

 

Felix,

I actually need to correct this statement earlier, see all the way below, as I think it might be adding to some of your confusion on figuring out your meter. The 1 is actually an I which is what you should get as soon soon as you set your meter to the resistance setting, others show OL. As soon as you short, or touch, the probes to each other you should either get 0's or a number depending on the accuracy of your meter and what settings you have available. For instance, on of my meters I show zero when set to 20K but if I go down to the 200 setting it shows .5 ohm. If you are measuring for resistance, make sure you subtract that number from your actual reading.

At this point, if you are touching your probes together and the I doesn't go away, you probably have a blown fuse in the meter. It may not seem like it because it is still taking other measurements, but that is how the meter is set up. It is only fused on certain channels. If you tried measuring voltage with the meter set up for current reading, or vice versa, you probably blew the fuse at that time.



"The 1 is actually an I which stands for infinite resistance. That is what you want when checking for very low or no resistance. The sensitivity of your meter can determine your readings when checking for very low resistance."

 

I'm confused? Maybe I'm getting too old for this. Going back a few Posts there's some information there that don't compute.

More than 16 Volts measured at the Battery. Bike Off.
More than 19 Volts measured at the Battery. Running.

These Bikes are supposed to produce 14.2 -to- 14.5 Volts Running.
14.8 Volts being a RedLine for Indicating Malfunction.

Pull-apart the Quick-Connection joining the Voltage Regulator to the Wiring Harness.
Examine BOTH halves for a sign of overheating and melting.
Pay close attention to the RED Wire's placement and Terminal End.

If the Quick-Connection melted and RED and WHITE Wires are melted together ... Unregulated current is going to the Harness and can cause all kinds of problems to the Electrical System.

Open the Headlight Bucket and Disconnect the Quick-Connect Pigtails coming from the Ignition Switch to the Wiring Harness.
The Bike should go dead.
Measure the Voltage at the RED Wire on the Pigtail of the Bike.
The Red (Hot) Wires and the RED-White-Striped (Hot Switched) wires should read 12 Volts.
Red = 12V
Red/White = 12 Volts when Ign On and Switch Closed.

 

I had the same issue this helped me a lot thanks guys! here’s a picture of the red and brown melted together in the connector behind the headlight.