electrical weirdness - CX100 battery light

[vents]

Hey guys,  I just re-installed the battery on my CX100 and for whatever reason , the battery light is now on constantly. It's even on with the key turned off . Electrical stuff is my weakness so any idea you may have is greatly appreciated !

btw, I was planning to ride tomorrow , so is my ride hereby cancelled ? The bike seems fine other than the battery light deal .

[Vasco DG]

How long was the bike inactive?

[Old Jock]

CX 100 a model I'm not that familiar with but is it the Bosch charging system?

If it is is the reference to generator charging light?

Did you measure battery voltage?

If Bosch then the first thing to check are the brushes on the alternator, that they are not worn, that the slip ring is clean and the brushes are making contact with the ring. I'd start there, next resistance checks on both generator stator and rotor.

I wouldn't go on a ride with the light I'm thinking of lit.

The bike will be running its ignition circuit off the battery and will continue to let you do so until you are in the most remote inconvenient place possible, with no cell service. At this point it will misfire then stop, if the bike is feeling magnanimous it will still be daylight.

Just my experience, Roy or Wayne are the God's whose advice is to be followed

John

[acogoff]

     It being on with the key turned off is a clue that maybe your ignition switch internals needs a look see.

[Kiwi_Roy]

     It being on with the key turned off is a clue that maybe your ignition switch internals needs a look see.

First of all I see you just recently joined, welcome to the madhouse.
 
I think Acogoff is probably right, something is wrong with the switch or a wire is shorted out near there.
If it was my bike the first thing I would do is remove the red wire off the battery and add a nice big in-line fuse 40 or 50 Amps, I add it to all my bikes in case a short let's out the magic smoke.
A trick I use while working on something powered by a large battery is put it in series with an old headlamp, the lamp when it's cold is almost zero Ohms and will provide enough current to power things up but if you accidentally short a wire to ground the lamp lights up giving a visual warning without taking out a fuse. In this case I would put the lamp between battery and red wire. 

Check at the fuse box F1,F2 & F3 should be dead with the switch Off, unplug the fat brown wire and see if it's livened by the key.
F3 is the one that's supposed to feed the light but often the wires at the fuse-box get moved around over the years.
BTW if you look at the schematic item 8 (ignition switch) the 3 different circles show the switch contacts in it's different positions On, Off & Park

Update: So it's a LeMans II then, we need pictures 
http://www.thisoldtractor.com/guzzi007/schematics/1978_LeMans_II.gif
I wouldn't be able to do anything without one of Carl's marvelous drawings to read and I do like to visit the lady at the top of page http://www.thisoldtractor.com/guzzi007/sportissimo.html


Arkansas, are you related to Bill the Eskimo spy by any chance LOL
It's all right, us Kiwis have a weird sense of humour

[dsrdave]

The CX100 is a lemans  2.  1979-1981.  Basically the same as a lemans 1 with a different fairing and 1000cc eng.  The diff. Fairing does result in a more complicated wiring as there are more warning lights and such.  Early ones had wires going the the warning lights.  Later ones had a circuit board.  If it has the circuit board I'd look there.  If it does not look at the ignition switch.

[vents]

the 1981 CX100 is probably most similar to the SP1000. Pretty sure it was a U.S. only and looks identical to a Lemans II.

[Old Jock]

Yeah I missed the fact it's on with ignition off.

As with Acogoff & instructions supplied by Kiwi_Roy

Sort that and then establish if its on all the time when the engine is running. It seems weird that you have both condtions, on when ignition off and also on when engine running, that appears to be pointing to 2 different faults.

But yeah deffo get the ignition off fault sorted first and progress from there

[oldbike54]

 Arkansas ? Where in that fine state ,over here near Oklahoma ? 

 Yeah KR is on to the problem .

  Dusty

[Kiwi_Roy]

If you haven't done it for a while remove the pointy fuses and polish up the tips, I usually dip the points in Vaseline.
Make sure the clips are holding the fuse tightly by bending them in a little.
Make sure all the wires are on the fuse block in the correct spot and the jumpers are correct.
If the Brown wire is not switching Off with the key, you need to check out the switch.

[vents]

Here's what I've gathered after checking this morning and re-checking just now . . . double ck'd this so my intial post isn't totally accurate .   

1.With the brown wire unplugged, the  battery light stays on regardless of key position. 

2. With the brown wire plugged in ,
    a.   the  battery light goes off when key is in running position , but
    b.   the  battery light comes on with key in the off position

3. The bike starts and runs normally , but the voltage at the battery is the same with engine running or not. 

4. I could not read any ( zero ) voltage at the fuse box at all .

thanks guys ! I appreciate the interest in this otherwise boring thread .

[oldbike54]

 Problem solving is never boring . In April my Jackal had an electrical issue on the road  These guys stepped up and helped solve the issue 

 Dusty

[Vasco DG]

Check the exciter feed to the stator isn't earthing out otherwise diode or ignition switch.

Pete

[Kiwi_Roy]

4. I could not read any ( zero ) voltage at the fuse box at all .
 

Only the top 2 should be alive with the key off
http://www.thisoldtractor.com/guzzi007/schematics/1978_LeMans_II.gif

With the brown wire off check it for Voltage, the brown wire should only be alive with the key turned on.
Fuse 4 is fed from a different contact of the switch, its for the tail light which alive in On and Park positions


From your findings 1, 2a, 2b I'm starting to think you have the wire for the charge light on the wrong terminal of the voltage regulator, it should be on the 61 terminal
I think you may have it on a terminal that is Hot with the key Off Check the 61 terminal on the rectifier, it should be dead with the key off.
If you find 61 is alive pull the wire of D+ and report back.
You might have a bad diode as Pete suggests but let's not go there just yet.

Here's my interpretation of your findings
1 With the brown wire Off the light is trying to liven up the fuses, it doesn't care where the switch is.
2a With the brown wire On and the key Off the light is tying to power the fuse as above.
2b With the brown wire On and the key On the brown wire is powering the fuses instead of the light so it goes out.

[guzzimike]

I  have owned my 1979 CX100 since July 1997. I have had three battery indicator light "ON"  issues over these years.

Invariably on these three occasion ( for me at least), it was the Rotor which turned out to be the culprit. Shorted windings.

If you think about it, it makes sense, considering that a rotor is a device directly related to your charging system, which operates under some fairly violent mechanical stresses.


More to the point, let us count the strikes against you ( your Rotor, that is .. ) .



Your Rotor happens to be designed as a fast spinning, electro-mechanical assembly made of tightly wound, thin Copper wiring.

<  Assembly Components = Strike One >



Your Rotor is located located at the front of your engine - This a physical location which gets HoT when the engine is working. If we factor in Heat Cycling ranging from Cold engine start to hot Engine cool down, and repeat this sequence ad-infinitum, we can easily visualize how we can have minute stress fractures forming in the thin Copper wiring.

<  Hot / Coid Cycling copper wiring = Strike Two >




The Rotor Assembly, as  implied by it functional name, is a spinning core of iron wrapped in that fragile, thin copper wire, and ALL of this mass is rotating longitudinally at an average 4500 RPM ( give or take a few..)  These Rotational forces impart their own adverse brand of mechanical stress  loads onto the thin copper wires, which we've already seen are an integral part of the assembly, and also may developing to some extent or another those Heat Cycle-induced minute stress fractures.

 < Centrifugal Stressing =  Strike Three >


And  YER OUT!


 
 
This is why, If I had to take a shot and pick any part of the Guzzi CX100 Le Mans Electrical System which would be most likely to fail and to exhibit the dreaded "Not Charging"  Light; I'd have to call it a Rotor with wirings in short-circuit.
 

So, How do we Test to see if our Rotor is  Kaput..?


Best way to check the integrity of the rotor is to pull it out. You need a special tool for this. It's akin to a Gear puller in general function, but different. I do not know where to source one ...maybe E-Bag, . Anyhow, Once the Rotor is out, use a VOM to check resistance of that thin copper wiring.

Choose Resistance in OHMS, set the dial in Autorange, or on a scale range where you have the ability to read up to 5 Ohms ( at least )

Your VOM will have two leads, One RED, One Black ( usual configuration )

Locate and identify the two copper rings located at the Front of the Rotor Assembly. These rings run Parallel to each other.

Place one lead on the front ring, place the other lead on the second ring. Make sure that they do not touch each other. We want to read the Rotor's Wiring Resistance, NOT red to black probe resistance..

A good Resistance read ( Ohms ) should be 3.4 Ohms. If it is not anywhere near that value, you need a replacement Rotor. If its close, but not exactly within that Ohms value , you need a new rotor.

Look, by its very nature, a Rotor will go bad , given enough time and exposure. And when they go bad , weird Shiite can occur, including some strange Battery Light signals.


At this point, we have both Good and Bad news..


The Bad first..


The Bad news is a replacement rotor runs about $70 - $80. ( The Rotor pulling tool is another $6 - $8  - by the time you factor in shipping, figure that you'll be into it to the tune of $100.00 - give or take    )


The good news is that  Here's a good source, with Rotors and Rotor Pulling Tool in stock

http://www.mgcycle.com/index.php?main_page=product_info&cPath=37_161&products_id=760

http://www.mgcycle.com/index.php?main_page=product_info&products_id=4631


Good luck to you... 








-

[Testarossa]

The rotor-pulling tool is just a tool-steel dowel. Make your own by cutting down a 6mm hex key. You need a rod two inches long.

Heat is the enemy in the alternator (though a leaking front crank seal won't help). Vent the housing by putting a couple of washers on the four allen screws that hold it onto the chain case -- the washers go between the housing and the case, of course, to make a narrow air gap. Or buy one of these: http://www.mgcycle.com/index.php?main_page=product_info&products_id=784

With some airflow through there the life expetancy of every alternator component improves. Without it the insulation melts on the connectors.

[Chuck in Indiana]

The rotor *is* the most common failure, but there's no need to pull it out to check it. Just pull up on the brushes and put a match or some other insulator under them and check the slip rings.

[vents]

Only the top 2 should be alive with the key off
http://www.thisoldtractor.com/guzzi007/schematics/1978_LeMans_II.gif

From your findings 1, 2a, 2b I'm starting to think you have the wire for the charge light on the wrong terminal of the voltage regulator, it should be on the 61 terminal
I think you may have it on a terminal that is Hot with the key Off Check the 61 terminal on the rectifier, it should be dead with the key off.
If you find 61 is alive pull the wire of D+ and report back.

I have no idea what the 61 terminal is you're speaking of . Don't see it on the diagram.

here's the latest .....

1. with the KEY OFF - the bottom 2 fuses are hot and the brown wire is dead.

2. with the KEY ON -  all 6 fuses are now hot and the brown wire is hot .

3. Battery light is ON when key is on or off.

would love to post pics if I could figure how. Maybe I don't have enough posts yet ? no idea.

[Groover]

Odd one. Be sure all grounds are connected and clean. Big ground cable to the frame, also check the smaller ground wires near the regulator and also at the rectifier. Black wires.

[Old Jock]

Terminal 61 is on Carl Allison's wiring diagram and its the feed for the light from the rectifier.

The fusebox and ignition sound correct.

Was any other work done on the bike other than the changing of the battery? Obvious I know but are all the cables on the battery, sometimes over the years stuff gets hacked about.

I'd check all the grounds as Groover suggests.

The only other thing I can think of is, as has been muted by Pete, a diode failure in the rectifier and its receiving a back feed via the rectifier.

[Guzzistajohn]

So vents, did you get this figured out? Being a cx owner myself, I was looking for a learning experience.