Brake fluid sensor

[XJ Rob]

I finally got the XJ on the road. Woo Hoo!! What a ride! There is only one thing I need to take care of now. The Brake light is on, on my monitor.
Is there a way to check the sensors? I traced the wires from the rear master to the headlight bucket and they are in good shape (no breaks in the wires) Both wires coming from there are white with a black stripe. The ones coming from the rear master are white/w black stripe and just plain black. Is there a certain way they hook up to the two W/B wires coming back to them?
I've looked at the Electrical diagram in the manual and it has a (NC) in the diagram. What does NC stand for?
I searched it the tec tips but didnt find anything there.

I rebuilt both masters and took the floats out but didn't think it made a difference which way they went in,as far as upside down.
Any help to point me in the right direction would be great.
Thanks

[0011mixam]

NC stands for "normally closed".

When I re-built my XJ1100, I'm pretty sure it made a difference which way the floats went on the sensors. The floats have magnets in them which operate a reed switch, depending on their position. According to the wiring diagram, the front and rear sensors are in series, so if either one goes open the brake warning light will come on. You can check the sensors with a multi-meter; you should have continuity through each sensor when the float is up (ie when the fluid level is where it should be).

[Lamric]

Hope this info helps, it's from the XJ1100 "Computerized Monitor Troubleshooting Manual"

XJ1100 Brake Fluid Monitor Circuit Diagram


XJ1100 Brake Fluid Monitor Testing
Pic 1
Pic 2

[XJ Rob]

I checked the rear sensor with the float in every position. I do NOT have any continuity through it. Nothing, zip, zilch. Not quite sure how the reed switch works but I know the magnet is good on the float. I put it to another magnet and it attracts one way and repels the other. Maybe the switch is bad or just stuck. Either way it's not good. Is there a way to pull these switches apart? Is this something that just stops working?
When you say "reed" switch, I think of something like a squeaky toy with a small metal reed to make it squeak. The float slides up pulling the reed outward and makes contact therefore having continuity. Or am I way off??
I found a NOS for 47.00 plus shipping but I don't want to spend it if I don't have to. I know that it only monitors the fluid level but I'm anal about checking fluids and having things work correctly also.
When I rebuilt the masters I tried to pull the sensors out but I didn't want to break it,so I left it alone. It was pretty tight. I was afraid of a leak after I put it all back together. Bike masters are new to me so I wasn't pressing my luck.
I'm more afraid of NOT being able to ride than breaking the part. I've already had to replace a couple parts (I broke) do to ignorance. But that was before riding season. Could have saved a few bucks if I had slowed down and not be in such a rush to get it done. But the season was approaching and it seemed I was never going to finish.Turns out I was wrong.

[0011mixam]

I call it a reed switch, but it's hard to see if there are any moving parts. Similar magnetically actuated switches are also used in the two buttons on the bottom of your gauge cluster.

Since both brake fluid level switches are in series, if either one goes open circuit your brake warning light will come on. You can verify this by jumping across the two wires in the wiring harness that connect to the rear brake fluid sensor. If your warning goes away, then the problem is definitely in the switch. Then your options are to either replace the switch or permanently jump that circuit and lose the ability to monitor your rear brake fluid level.

[Yahman]

I checked the rear sensor with the float in every position. I do NOT have any continuity through it. Nothing, zip, zilch.

Then the sensor circuit wire must be grounding somewhere. The light only comes on when there is a connection in the sensor (fluid empty). when the fluid is full there should be "no continuity" and "no light".

The reed switch is much the same as the pickup for a digital bicycle speedo.

Larry

[trbig]

On my XJ, if I don't put the bike on the sidestand, and fill the resevoir completely until it is running out.. then throw that screw in really quick.. my light will come on sporadically. It comes on and makes the warning light flash. I turn that off.. then a few minutes later it comes on and makes the light flash again. Annoying as heck.

I know you say you want stuff to work right.. but sometimes, with old parts, you gotta do what you can do. Jumping the wires is an option. Brake fluid levels aren't as critical in my opinion as engine fluid levels. You should be able to see if you are losing any brake fluid, and they will get spongy before they actually quit working.. except in a rapid loss situation like a hose break or something.

I went to an XS rear M/C for a while, which has no place for the sensor wires to connect.

Tod

[Yahman]

However after studying the bad photo in the manual, I am led to believe that they may be back-wards.

Now I guess I will have to go check my bike to clear this up in my head.

Larry

[Yahman]

WOW!!! am I confused today...

After reading the manual (page 6-28) I had the impression that the reed switch had continuity when the fluid level was low. WRONG!

After testing the brake fluid sensors on my XJ, I will tell you that there is continuity when the fluid level is full. There is no continuity when the level is low.

So my now corrected and official opinion is that one or both of your sensors is bad , or you have a broken wire or connection. That is just MHO and I'm sticking to it.

I will now go back to my corner, sorry for wasting your time.

Larry