[ThePass]

So, this is a continuation of a thread I made a month ago. I still haven't figured out the problem and so the bike is still down.

Long story short, the bike just shut off while idling perfectly normal after riding about 40 miles with no apparent problems. Went to turn it back on, and fuel pump would not prime.

So, I've gone through the checklist - the fuel pump is OK. fuses are OK. Relays are OK. All that is left is the Bank angle sensor (called lean angle sensor in the wiring schematic) and the ECU. I performed the test to see if the bank angle sensor was working properly, and it is not i.e. with it plugged in and key to ON, if I tilt it 60 degrees, it does not click like a relay. At first, this made me think I had found the problem - bad bank angle sensor - then I found out they were ~$100 and I put off buying a new one. Good thing.

I thought to test the wires going into the sensor. Attached below is the wiring schematic if any of you know how to read it better than I. The green wire should be ground. It is a ground that is shared with other things like all the lights, etc. The other two wires that go into the sensor are power wires.

When I tested these wires, I was very confused to find that with my multimeter's negative lead on the neg. lead of the battery, if I checked for voltage on the green wire (ground) it sees 12 volts!!! I then realized that all of the other things which also use the green wire for ground - like the turn signals and headlight and taillight - also do not work when key is ON.

So, what the hell could be causing this? A problem inside the ECU?? Please help me out. I feel like I've gotten to the point where I don't know enough to be able to fix this.

-Ryan

 

[bladeracer]

When I tested these wires, I was very confused to find that with my multimeter's negative lead on the neg. lead of the battery, if I checked for voltage on the green wire (ground) it sees 12 volts!!! I then realized that all of the other things which also use the green wire for ground - like the turn signals and headlight and taillight - also do not work when key is ON.

So, what the hell could be causing this? A problem inside the ECU?? Please help me out. I feel like I've gotten to the point where I don't know enough to be able to fix this.

Battery connected backwards?
Are you sure you've got the negative lead?
It's on the right side of the bike and connects to the starter motor.
You should see continuity (not voltage) between the green wires and anywhere on the frame or engine.

 

[ThePass]

This is the negative lead and the battery isn't backwards. The bike was running perfectly up until it just shut off when I pulled up to a gas station.

 

[sheepofblue]

It would seem that if there was a short on that line you would get 12V (potential at the bank angle without a ground) Look for a short.

The preceding was a thought so don't quote me

EDIT: oops I meant break not a short, in other words your ground wire is broken somewhere and when you hook the meter up it is just reading potential.

 

[Jason-K]

As above, it has to be an open circuit between the chassis/earth and the point where you are testing for voltage....if you are measuring the correct wire that is.

Instead of using the -ve battery terminal as negative, try tracing the green wire back to the earth point and testing again. If you still get 12V, your problem is going to be in the wiring between those two points. However, I suspect you will get 0V, indicating a very poor earth.

It looks as though (If the schematic is actually correct, quite often not....) there are only 2 earth points, one that should have a fair bundle of wires, and one directly from the ECM. Basically everything is earthing to the main earth point, so I wonder myself how you have the instrument cluster working, unless it has found an earth back through the ECM.

Would be interested to find out how you go with it.

Godd luck,

Cheers

 

[cbr lonner]

is there an alarm immobiliser fitted?

you can also bypass the fuel pump re-lay (get pump running)but you will need the Haynes for that info

also check the connector blocks at the rear of the dash clocks aren't lose

 

[denzee]

If you see voltage on the ground wire while everything is still connected, sounds like a bad main ground, where all the green wires attach to the frame or another ground connector. You are basically doing a voltage drop test. Check all your grounds and ground connectors.

Simply check a ground by putting your voltmeter on each side of the connection you want to test. If the connection is good, your voltmeter will read less than a volt. The worse the connection, the higher the voltage.

 

[ghbzorro]

If you see voltage on the ground wire while everything is still connected, sounds like a bad main ground

By definition, if you are measuring a 12 volt potential, then that cluster of wires is not a ground any more. So either its connection is messed up, or the connection at the battery is messed up. Period.

 

[ThePass]

It's raining pretty hard today so I am sitting inside thinking of ways to possibly fix this, and I'm wondering: could I take a new wire, splice it in with the green wire right by the bank angle sensor, and run it to a good ground spot, basically making sure that the ground is solid? Or would this be bad for some reason?

This whole idea that connecting the voltmeter between two points on a ground wire actually shows more voltage as the worse the connection is is new to me - I figured it literally had to mean there was a positive wire somewhere crossed wit the ground giving it positive voltage.

 

[Jason-K]

ThePass - The reason you are measuring the 12v on the green ground wire is because it is no longer a ground...you are measuring a "potential difference" between those two points.

In a very basic nutshell, you have 12 volts at the positive battery terminal. You will ALWAYS measure 12 volts between the end of that wire, regardless of the components connected to it(except open-circuit components like a switch) and the negative battery terminal, until the end of that wire is connected to the negative terminal. Once it is connected, you will then see 0 volts between the negative and the earth-side of the last component, as it should be almost no resistance in the wire itself.

The worse the ground is, means the more the "voltage drop" across it. Which in turn means a higher resistance. If you measure the full battery voltage, it means infinite resistance, which means a complete open circuit...eg broken wire.

If you had a positive wire connected with ground, that would be a dead short, meaning a huge current and some serious melting of wires would be apparent.

You could, as you say, connect a wire between the earth side of the lean angle sensor and earth, but it would be much better to fix the actual cause of the problem. Depending on where the open circuit is, your idea may only fix the earth issue to the lean angle sensor, not the rest of the symptoms that go with it.
Look for the main ground bolted into the chassis, unbolt it and you will probably find some extreme corrosion, or you might not find the bolt at all and just a bunch of green wires hanging loose. You just need to earth them properly.

 

[thatguy21]

i am having problems like this on my 2003 cbr954rr but the taillight still comes on and the display shows up but there is no backlight and the headlights dont come on and the fuel pump doesnt prime i have no clue what the problem is on mine

 

[ThePass]

ThePass - The reason you are measuring the 12v on the green ground wire is because it is no longer a ground...you are measuring a "potential difference" between those two points.

In a very basic nutshell, you have 12 volts at the positive battery terminal. You will ALWAYS measure 12 volts between the end of that wire, regardless of the components connected to it(except open-circuit components like a switch) and the negative battery terminal, until the end of that wire is connected to the negative terminal. Once it is connected, you will then see 0 volts between the negative and the earth-side of the last component, as it should be almost no resistance in the wire itself.

The worse the ground is, means the more the "voltage drop" across it. Which in turn means a higher resistance. If you measure the full battery voltage, it means infinite resistance, which means a complete open circuit...eg broken wire.

If you had a positive wire connected with ground, that would be a dead short, meaning a huge current and some serious melting of wires would be apparent.

You could, as you say, connect a wire between the earth side of the lean angle sensor and earth, but it would be much better to fix the actual cause of the problem. Depending on where the open circuit is, your idea may only fix the earth issue to the lean angle sensor, not the rest of the symptoms that go with it.
Look for the main ground bolted into the chassis, unbolt it and you will probably find some extreme corrosion, or you might not find the bolt at all and just a bunch of green wires hanging loose. You just need to earth them properly.

Thank you so much for taking the time to explain this to me.
My main ground - the collection of several green wires meeting together with a bolt in the frame under the tank - is intact and tightened sturdily. I remember checking for voltage at that main ground and saw only ~0.5v so I'm guessing that means the ground point is good and not corroded... so the big question at this point is, where else could there be a failure in the ground...?
Whenever this storm lets up I will inspect further..

 

[cbr lonner]

i am having problems like this on my 2003 cbr954rr but the taillight still comes on and the display shows up but there is no backlight and the headlights dont come on and the fuel pump doesnt prime i have no clue what the problem is on mine

id check the connector blocks at the rear of the clocks as i had this with my 900rrs.

 

[Jason-K]

No probs mate.

I'd just trace those wires back up from the main earth point, and there should be several connectors. Re-seat those connectors, make sure they aren't melted or anything. Measure the voltage between both sides of the connectors and that should tell you if it's OK or not. Other than that, it will be the wires themselves. Good luck

 

[ThePass]

Ok, big news:

I went outside during a lull in the weather. I decided that I wanted to make sure that the problem really was the ground wire not grounding. So, I did what I asked about above and jumped a new wire from the main ground to the green wire right before it goes into the bank angle sensor. Turned the key to ON and EVERYTHING WORKED - lights, turn signals, the fuel pump came on, everything!

So, obviously this is not a fix, just a test. The big problem I have now is that that green wire leaves the bank angle sensor and dissapears into the wiring harness. I have no way to actually physically trace the wire and find where the discontinuity is.

As far as I can tell, I need to clamp the fuel lines, take the fuel tank off, take a razor blade and cut open the wiring harness and follow that green wire it's entire length to find the problem area. What do you guys think? Is that what must be done? Is there another way? I'm not looking forward to this..
'
-Ryan

 

[sheepofblue]

To start take the wiring diagram and see what is between it and ground. You may be able to test points along the way to narrow it. If that works and you have it narrowed visually trace that section of the wiring harness. Look for a worn though or crushed section. Give special attention to any area you worked on before this issue occurred (I find I am my own worst enemy). If that fails try feeling the harness and only as a last resort cut.

To illustate:
The first point I see tied is the headlights so see if you have 12v on both sides. If so procede to the horn for the next test. If still have 12v on both sides test the kickstand switch. Continue checking each dot until you find a good ground, the issue is likely in between there and the previous item tested.

Hope this helps.

 

[ThePass]

I get what you are saying and that was my first idea but it seems that while the wiring diagram is accurate as far as what components use what wires, it would seem that the diagram was drawn with the intent to fit everything on one page of paper and therefore does not accurately show the series in which the wire travels - for example, In the diagram the rectifier is closer along the path of the green wire to the main ground than the tail lights but when I tested the grounds today, the ground for the rectifier is good, but the ground for the tail lights is bad. Odd.

 

[Jason-K]

You're correct in saying the diagram is arranged to fit the page, not necessarily in the correct order of connection.

Really, the only way you're going to get this fixed is to remove the tank, and anything else in the way....then start tracing the wiring.
Usually, I would disconnect the battery and actually test continuity of the wiring instead of testing for voltage drop. That way there's not going to be any arcing if you mess up and short across a +ve terminal somewhere.

Latch one of your meter leads to the negative battery lead, and use the other to poke through the insulation of the (suspect) ground wire all the way back to the main ground bolt, until you find the point in which you get good continuity.
If you come across a connector, test both sides (same wire, of course) for continuity. If it's not a connector fault, it is most likely to be visible damage to the insulation.
Check for cable-ties that may be too tight and worn through.

 

[sheepofblue]

OK so the diagram won't get you there but the process is sound so...

Find a fiche (I went to Ron Ayers) and it looks like they show 2 harnesses (they list it as a 900RR though) looking at the harness picture you should be able to get and idea of the sequence of items on the harness. This might save you some work but if not the previous post about pulling the tank/etc is your next step.

 

[rnareppa]

So, what was the final verdict on your issue Ryan? I might be having grounding issues too on my bike, wanted to know what you found.