TCI voltage readings

[nikonyamaha]

Does anybody know what the voltage readings ought to be at the ignitor unit? With the battery showing 12.6 VDC w/ no load, the following readings were made:

Ignitor unit pin numbers, looking at unit
[ 1 2 3 4 ]
[ 5 6 7 8 ]
Key on - figures in VDC. Voltage read at the TCI connector.

connector pin# / wire color

1 Gry - motor off: 11.1, motor on: 7.0
2 Red/Wht - motor off: 11.1, motor on: 8.0 - 9.0
3 Blk/Wht - motor off: 6.1, motor on: 6.0
4 Blank
5 Red/Wht - motor off: 11.1, motor on: 11.3
6 Red/Ylw - motor off: 0.0, motor on: 10.8 at start up then back to 0.0
7 Org - motor off: 11.0, motor on: 7.0
8 Blk (ground)

Are these good readings? I'm assuming that wire 6 is an output signal. If the readings are off, is the ignitor bad? Or is there something else that feeds the TCI?

[bikerphil]

Copied from the Yamaha service manual.....

[dbeardslee]

Readings are supposed to be taken with the ignition on, but not running. If that's the way you took the readings, those 11v numbers are pretty low. If it drops below 10.5v the TCI won't fire the coils. Looks like it's time to start cleaning/replacing electrical connectors. I went through and cleaned my connectors when I first got Betsy, but I was still only getting around 11v at the TCI. I went back through them, clipped of the wire ends and crimped new connectors and in some cases replaced plastic housings. With each one I did I recovered 1 or 2 tenths of a volt at the TCI. By the time I was done I was back up to a full 12v.

The problem with just cleaning connectors is that you can get corrosion that works it's way back inside the wire sheaths, and no amount of cleaning is going to get it out. That corrosion causes resistance, resistance generates heat, and heat can leave you stranded on the side of the road. Geezer sells a nice compound double crimper for around $25 that will do a perfect factory crimp. I'm pretty sure he sells the wire ends and housings too. Pay particular attention to the red/wht wire as that's the one that carries the juice to the ignition. And don't forget the handlebar kill switch and starter button, and the connectors that are hidden behind the fuse block mounting plate. Replacing connectors is a tedious PITA, but it pays off.

[Larrym]

Oh Fudge!!!

nikonyamaha,

Ahhh....The joy of technical specifications and the real world/real time verification(?) of those measurements. I'm assuming that you're doing these tests just cause of the fascination factor of owning an XS and having the opportunity to leave no stone unturned in your exploration of the XS and all it's wonders. Surely theres no electrical gremlin which prompted you to look into this area, right??

So....

With the battery showing 12.6 VDC w/ no load, the following readings were made:

Ooh. <Awkward silence...> So that's what the battery read when you measured it with the key in the off position? I'm ok with that. What I am a little uncomfortable with is that there is no reading/measurement of the battery voltage at the very end of your "tests" at the very moment you switched the key back from the On position to the Off again. Could be kinda important.

Thing is that if you hook up a meter to the battery and then just turn the key on....the voltage starts to drop cause the battery is technically under a load. Sure it's a small load (hopefully...) but still a load. How fast the voltage goes down is dependent on the "load" and the battery condition/capability.

The TCI is full of active components like transistors and such that do there very best to work with the input voltages they get and then output what they can. I mean they'll do ok up until the point where the input voltages are below what they can work with and then: OOPS!

So while you were doing those tests as properly and in a timely manner as possible <place probe here-read meter-write down reading-place probe there- read meter-write down reading-ad nauseum...):

The battery had to have "dropped". A good battery properly sized and in excellent condition would hopefully not drop below the "acceptable" voltage level (in the eyes of the TCI...) during the real world and real time that it took you to do the measurements, right?

That's the question: since you had your meter in/out of those test points you couldn't have been monitoring the actual battery as it supplied the voltages at the source.

<More awkward silence....>

It may or may not have dropped far enough to to sorta give you misleading information/data from the tests at the TCI test points.

Proposed Action: Hook up a meter to your battery. Take a reading. then turn on the key and watch for a time interval similar comparable to the time that it took you to perform your exploration of the wonders of the TCI test points.

If the results are that the battery "wimped" on you??? Then I'd say while addressing the wires/contacts of, at, to/from the TCI (or anywhere on these marvelous machines for that matter) is a good thing....

Make sure the battery is OK before exploring elsewhere. It's part of that whole "make sure that you're sure" before reaching a conclusion based on the data you gather.


HTH

[Larrym]

Advice or Answers. (Chicken or the Egg.)

nikonyamaha,

Yeah....The previous post of mine had some advice and well, you did actually ask a question. So I prob'ly should try to provide a genuine answer eh?

I'm assuming that wire 6 is an output signal.

Umm....uhhh. It's all relative. Really, I mean that. As far as I understand it, TP(Test point #6/the redand yellow wire) is an output signal from the starter soldenoid and an input signal to the TCI. (Crap!!!! I NEVER spell solidenoid correctly.)

Functionally, it is used to tell the TCI that you've pushed the starter button and are trying to get the air/fuel to ignite in the cylinders. (What a glorious feat that is when it does happen.) During this pressing of the button and starting attempt the TCI sorta does it's own magic of increasing the supplied voltage to the coils: Hotter and more reliable(?) spark in order to get the beasty to run on it's own. Release the button and then the coils get the supply volatage reduced through the use of something called a "Ballast Resistor". Sorta to extend the life of the coils by matching their "continuous" current/voltage load rating.

Yah...I know. Kinda complicated. But for more wonders and amazement take a look at this:



http://farm5.static.flickr.com/4054/...1ae5cbd4_o.gif
(Courtesy of Member 3Phase)

It is a 1980 XS1100G were talking about, right???

[nikonyamaha]

Larrym,
Yes it is a 1980 XS1100G.

The electrical gremlin is that the starter will spin but no spark at the coils when the bike sits in the sun at 95 degrees for 7hrs. In the morning and in the cool of the day it starts like its suppose to. So it seems it might be temperature related and with 116,000 miles on the clock could it be with corrosion under the wires and coupled with the Texas summer heat I might have high resistance which leads to the starting problem?

My testing method: with ignition on and motor not running, initial battery voltage was 12.6V when I started and dropped down to 12.3V when I finished.

When starting the motor, voltage drops to 11.8v, moves to 13V at 2000rpm, and 14-15V at 3000+ rpms. I think the rectifer is doing its job. All ground terminals are clean, fuses replaced with blade style, coils ohm correctly (NOS replacements), ballast resistor OK, pick up coils in spec, handlebar kill switch and starter button contacts cleaned. The only thing left is fresh connections like dbeardslee suggested. And that might mean a new battery ground cable as well. The cable, not the rings, look really oxidized.

[dbeardslee]

I've seen ignition coils exhibit sensitivity to heat, but otherwise check out OK. Unfortunately it's hard to confirm unless you've got a spare set of known-good-coils sitting around that you can swap in. You might try testing them for internal shorts by testing the continuity between the feed wires and the high tension wires. Should show no continuity or real close to it. If you get continuity between them, that's a bad thing.

If it was mine, the first thing I would do is find out what happened to the missing volt at the TCI. Temperature extremes aren't good for batteries - maybe the extreme heat is causing a drop in voltage? Don't know - just cogitating out loud. From the readings you originally posted you're only 1/2 volt from not having enough juice to fire. Corrosion may be robbing voltage at the connectors, or it might be the battery itself, or a combination of the two. How old is your battery? Has it got water in it? Have any of the water levels in the cells ever dropped low enough to expose any cells to air? Will it take a charge from a charger?

[Larrym]

Step Right Up and See the Electronic Brain: 5 Cents

nikonyamaha,

The battery drop of .3VDC is not enough to be a "dealbreaker" as far as your measurements of the TCI voltages. (Usual disclamer/weasel clause: "In my opinion".)

I'd agree with you that the starting/charging system is doing all right according to the readings and what the bike is doing. (Gosh. It's a real treat to have that one-stop-shopping where someone provides all the right data right there for easy consumption. Thanks!)

Along with chasing the green corrosion off those connectors I'd suggest that you actually remove your TCI assembly and take a peek inside.

From what you're describing, I'd say that it just may be possible that your TCI printed circuit board may have a small crack in one of the "traces". Either that or maybe one of the pins that connect from the circuit board to the outside world has vibrated loose.

The connection is ok when its one temperature and when the temp changes the "joints" (There's humor here......wait for it....) make or break according to their own "expansion/contraction" preferences.

I's say open up the TCI and take a look at it. If you're like me you'll use a magnifying glass and spend way more than 5 minutes giving it a thorough evaluation. (Twice, right?? Just to be sure.) Use good lighting. Don't be afraid to touch stuff and try to wiggle what you know shouldn't move. Maybe you'll have that "Eureka" moment. Maybe not.

Then you prob'ly know your way around with an electrical soldering iron: overheating stuff and "the bigger the blob-the better the job" will get you in trouble. I mean just for fun go to the Yamaha dealer and ask them kindly for another brand new TCI unit.

If you don't find the problem there then at least you've taken the nickel tour of the guts of a TCI.

I dunno...I thought it was fascinating and time well spent.

Besides...if your TCI does a "hard Fail" then theres a test to confirm that. (I mean other than just cranking the starter till the cows come home...)

[3Phase]

Nikon, I see LarryM beat me to the rest of my questions/suggestion! Nice work, Larry!

You may need more than two hands to hold the voltmeter probes and push the starter button at the same time but check the voltage drop across the suspect cables when you start the bike. If there's anything but a couple of millivolts across the cables they're bad or a connection is bad.

What's the voltage at the + side of the coils at the ballast resistor connection when cranking the engine in the cool morning? The hot afternoon when it won't start? What's the voltage when the engine is running? It should have full voltage when cranking the engine and the ballast resistor is bypassed by the TCI.

Are you absolutely certain there is no spark after the bike has been left in the sun or does the engine just crank for a long time and fail to start?

Is the bike parked on the sidestand or the centerstand? Is there any sign of gasoline in the engine oil? It'd be more likely the fuel is leaking out of the float bowls and flooding the engine than sunlight causing the ignition system to fail.

It's not entirely impossible but if sunlight is able to kill the ignition you should notice problems as the bike warms up. Unless you're parking under a magnifying glass everything gets a lot hotter when the engine is running and the bike is moving than just leaving the bike sitting in the sun for 7 hours!

[crazy steve]

I dunno, I kind of like Larry's idea of maybe a bad connection in the TCI. It's under the seat, so engine heat wouldn't affect it, but roasting under the Texas sun with that black seat above it might be enough to cause components to 'move around'. Next time it does it, maybe pull the TCI and stick in the freezer for a few minutes.

I had a TV that did exactly the same thing; intermittent problems that would come and go for no apparent reason, and we didn't make the heat connection until the very end (summertime, and hotter days caused it to act up more). The set was under warranty, and drove the techs crazy until they sent the 'old guy' (all of 45! ) to fix it. He spotted some not-soldered-quite-enough connections, re-did them all, and the set worked great until the projectors went south...

[Larrym]

Down the Rabbit Hole He Went...

Nikon, I see LarryM beat me to the rest of my questions/suggestion! Nice work, Larry!

3Phase,

C'mon. You know that I never actually read what people write in their "presenting Problems" posts or even pay attention to anything with Numbers in it. It's all just random guesses on my part with my Magic 8-Ball providing direction when I lose my focus.

Now you've gone and done it f'sure: Asked him for more data. You know that they go rabbit 90% (Thanks magic 8-Ball) of the time when anyone does that.

Darn. And we might have been able to actually appear that we DID something useful....

[3Phase]

I dunno, I kind of like Larry's idea of maybe a bad connection in the TCI.

Yep, it's possible but Larry covered the TCI/solder/cracked board part!

It's all just random guesses on my part with my Magic 8-Ball providing direction when I lose my focus.

Ask The Magic 8 Ball

Me: "Is it the engine flooding when the bike is parked in the sun for 7 hours?"
8-ball: "Hmmm.... My sources say no."

I guess that's it then, it's the TCI!

[Larrym]

Place ya bets...

Me: "Is it the engine flooding when the bike is parked in the sun for 7 hours?"

I'm in for a part of that action.

I'll "see" your flooded engine and raise you a pressurized fuel tank due to a Plugged Gas Cap Vent.

<Note to self: Do NOT bring CC along on Vegas trip...>

[Larrym]

Duplicate/Recreate the Conditions

3Phase: Are you absolutely certain there is no spark after the bike has been left in the sun or does the engine just crank for a long time and fail to start?

Jeez....It's answers to questions like these which could unravel my whole "working theory"(Translation: Wild A$$ Guess) about the TCI being the "problem".

I mean all nikonyamaha would have to do is pull his plug wires off the installed spark plugs, stick some known good plugs in the ends of the high voltage wires, and lay them casually on the engine head against the metal.

<Jeopardy theme Song for 5 hours...>

Nikonyamaha comes back in the heat of the day. He puts the key into the ignition. twists it to the right, and then pushes the starter button. He looks down at the sparking plugs putting on a light show.

My TCI theory blown sky high. (Sob....) It really was a good one..sorry to see it go.

It's so easy for me to get attached to'em. (Lower lip tremble...)

[3Phase]

Nikonyamaha comes back in the heat of the day. He puts the key into the ignition. twists it to the right, and then pushes the starter button. He looks down at the sparking plugs putting on a light show.

Yep, I was kind of assuming Nikon knows how to check for spark and wasn't finding any after the bike got left in the sun. It is also possible that it was bright outside in the sunlight. The spark got washed out by the light so he couldn't see anything and stopped cranking the starter so he didn't kill the battery or light the fumes from the hot gas tank on fire by running an open spark directly underneath it.

The XS is a relatively simple machine but it can be intimidating when you're looking at all those fancy petcocks; multiple fuel and vacuum lines; the sculpted aluminum cooling fins on the engine reminding you that it definitely is not a car engine; the fancy-colored spaghetti wiring that doesn't make sense until you've worked with it for a while and goes to the black boxes that make even less sense than the colored spaghetti but are supposed to make everything work!

The 'cold' voltage readings made at the TCI look okay; a little low on the battery voltages but good enough to start and run the engine. If there really is no spark when the bike gets left in the sun, the TCI voltages when the bike is 'hot' and won't start would be helpful.

The voltage readings at the ballast resistor/ignition coil/ballast start bypass function junction will show if correct voltage and current is actually reaching the coils when the engine won't start, not just the TCI.