Throttle Position Sensor TPS Part Number

A new battery should not be taking 10 Amps continuously.
These small (12-14 AH) batteries normally only take a small current.
It should drop to 1-2 amps quickly.
Is it possible that there is a problem with the new battery?

Did you measure the TPS voltage at the ECU connector when the MIL comes on?
Perhaps it is possible that you have 5 volts at the TPS but the ECU is not seeing it!
As long as it is above 0.4 volts at all times it should be OK.

Macka
 
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It is possible there is a problem with the new battery but the old battery was also drawing 10 amps. O‘Reillys wasn’t able to test either one. My Battery Tender doesn’t indicate problems with either one but I’ll take the old one to another shop and see what they can do.

I have not caught the voltage value at the ECU TPS input during the act. That may be my next mission.

Thanks to all for your help.
 
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I suspect you have a rogue current draw from something. What accessories do you have connected to the bike?

Another thing to check is the earth point for the regulator/rectifier as that earth is typically used as a "reference point" for the regulator/rectifier and if there is not a good earth connection it can cause problems.

One other vague possibility is the instrument panel could have a fault. One other member had nearly every other electrical component replaced by Honda (including the wiring harness from memory) and it turned out to be a faulty instrument panel. I cannot remember the exact symptoms BUT I do remember finding it very strange that the instrument panel was the cause.

Seagrass
 
You have an astonishingly high off draw. You can isolate the off draw somewhat by pulling individual circuit fuses until the off draw disappears. That narrows it down somewhat. Hopefully you have a schematic which will show you what is on each fused circuit.

Mike
 
Tourguy,
Seagrass may have a point there!
Do you have anything non standard connected directly to the battery rather than the fused circuits?
Forgive me if you pointed this out before. I have not gone back to re-read earlier posts.

Macka
 
Yes, Macka, I do have a 12v outlet connected directly to battery, but nothing is in it unless I am on a long trip.

BTW:
I've been working on that idea of "waking up" the TPS by exercising the throttle when the ignition /and/or motor is off to see if this will help get something working internally to the sensor. The "jury" is still out on this idea. I have been able to convince the MIL to stay off by this method and ignition off/on but it's not really consistent. When I follow this procedure, the sensor eventually starts working on the several test rides I've tried over the last 2 weeks or so.
 
Does it help to know that if I have not ridden for a week or more, the battery charger tells me the battery is still at 95% when I connect it for a charge? My thought is that if I had some rogue current draw by that direct wired outlet, it would cause the battery to be much less than 95%. The charger is an "automatic/smart" unit with a basic readout.
 
It wouldn't hurt to disconnect that 12v outlet just to see if that changes the picture.
 
Does it help to know that if I have not ridden for a week or more, the battery charger tells me the battery is still at 95% when I connect it for a charge? My thought is that if I had some rogue current draw by that direct wired outlet, it would cause the battery to be much less than 95%. The charger is an "automatic/smart" unit with a basic readout.

As a Mechanic, I can tell you that 95% is a bit of a "Red Herring".
I have a couple of similar "Smart" chargers that will show the same (95%) but it still takes a long time and lots of Amps to reach that 100% State of Charge.
When yours shows 95%, how long does it take to reach 100% and switch off?
If it is more than a few minutes the battery may be lower than you think it is.
A smart charger will bring the battery up from, say, 75% very quickly to 95% but the last 5% from 95 up is really the part that the battery needs.

This is a subject that I spend a lot of time trying to explain to my customers about "half or part flat" batteries.
It is long winded so not now. Maybe some other time.

I would have thought that, if the battery is near new, it should still be at 100% after a week or so!
Have you tried disconnecting the battery from the bike (earth lead) for a week and then see what it shows?
I don't expect that your extra outlet on the battery is a problem if there is nothing plugged in to it.
It doesn't have an LED "advisary warning" or similar does it? Just a "dumb" socket?
Some LEDs can draw enough to pull a small battery down over time.

I was away "up the bush" last night and when I started the bike this morning at 5 degrees C (my battery is 9+ years old) the fuel gauge needle DID drop to E during cranking but the bike did not log any codes. I actually made a mistake as the bike was still in 1st gear, as parked, and when I started it (with the clutch pulled in, as always) the bike pulled forwards a bit due to cold oil and clutch drag. It cranked slowly but still started without struggling too much.

Macka
 
I’m still battling my MIL 8 issue and also my alternator wires overheating problem. I now understand the alternator issue and will discuss that at another time but here is what I’m finding on the TPS.

I connected a data acquisition system to the TPS excitation, the TPS wiper, and the TPS return wiring at the ECM connector. I rode the bike for 16 minutes and collected over a hundred thousand rows of data at 100 samples per second trying to catch the MIL 8 event.

Although the error never displayed, I believe I captured a span where the anomaly occurred about half-way through the ride because the TPS voltage fell to 0.32V for about 3 seconds and rose back to 0.458V in about 1/3rd of a second. It never fell below 0.458V before the anomaly or after it. I believe that the data acquisition system’s input impedance may have influenced the circuit enough to prevent the MIL 8 from occurring.

During the 16 minute ride, the TPS excitation voltage always read between 5.016V to 4.994V referenced to the TPS return, that includes during the anomaly period.

I varied the throttle position over and over and coasted often during the ride. The anomaly occurred at the end of a coast/idle and ended while accelerating (picture attached).

I then took another 16K samples of data with the engine off. I twisted the throttle on and off numerous times and the TPS voltage never fell below 0.479.

I really want more data but nothing that I see so far points to TPS sensor, battery, or voltage regulator (especially since I have replaced them all).

I was beginning to suspect an E3 problem. Does anyone know if Honda gave a reason for the spark plug cap recall? It notes on the box that the 5K ohm resistor caps are to reduce RFI emissions. However, a seemingly random 3-second long EMI/RFI event is possible but doesn’t seem likely and it would likely show on all three TPS wires.

Although the small amount of “engine off” data I took doesn’t support this, I wonder if the throttle stop could possibly allow the throttle to close a little further on occasion (burr, debris, FOD, cable issue, ...)?!?

**** edited/added this “come to think of it, I never saw the MIL 8 before I had the local dealer install the Heli-bars riser that includes both new/different throttle cables” ******

The ECM TPS input could have an issue so I may replace that next but I may try to figure out how to bias it to 0.5V first to see if that helps.

Still accepting suggestions

Thanks,
Mark

C9935354-2194-4660-8C8F-6FDAE44E0965.jpg
 
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The service bulletin for the spark plug caps states:
The bike may experience misfires at idle during high ambient temperatures and stop and go traffic. The original resistor caps may discharge to ground while idling, causing a misfire.

It sounds as if both the original and replacement spark plug caps are resistor type to reduce RFI which I think has been standard for a long time. I suppose the caps sparking to ground could generate noise to cause your issue but not likely.
I'm interested in your alternator issue. You can measure a problem there. It may be somehow related to TPS codes so I would focus on fixing it 1st then moving to the TPS if it is still throwing codes.

----Edit----
I notice your trace lists ground at 1.862 volts if I read it right. That sounds high, what is the reference side of the DAC tied to?

Brad
 
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Hey Brad,
I should have mentioned that the ”Motorcycle GND” channel wasn’t connected. The low side was connected to a bolt on the engine but the high side was floating. I was going to tie the high side to the negative battery terminal but didn’t so just ignor that one. All channels were referenced to that bolt. The numeric values I gave came from an excel spreadsheet I dumped the data into and sorted. I subtracted the TPS return from the TPS wiper channel in another column and sorted from low to high, and several other ways while evaluating the results, and that column provided the values that I reported. They were very very close to the “TPS wiper” values but probably more like what the ECM input was seeing.

Thanks for the recall info. And yes, I do intend to deal with the alternator issue first but I will be pleasantly surprised if there is a relationship.

Thanks,
Mark
 
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Mark. I think that the Throttle Stop Screw is unlikely to be the cause of your problem unless there was significant wear in the shaft or bushes.
This is a really interesting but frustrating problem.
Three seconds at .32 volts should be enough to trigger a Fault Code so it is probable that you have found the reason.
Now you have to find the cause.
At this stage I have no idea as the supply side is steady at around 5 volts.
As an experiment I would try setting the closed throttle voltage a little higher, about .6v or .7v and see what happens.
I think that as long as it is under about .8 or .9v it should not upset anything too much.
This will not find the cause of the Code but may confirm that the .32 volts is the cause of the Code Logging.

We are all waiting to hear what you have found on the Charging problem.
Don't keep us in suspenders too long!

Macka
 
Now back to the alternator wires overheating. I finally realized that the alternator and regulator do not operate the way I would have expected them to. The alternator has no field coil and therefore it’s output cannot be varied, other than by varying the RPM. It basically puts out maximum current and voltage based on the RPM, although the load from the bike’s systems and accessories has an effect, it may not be what you might expect. The service manual doesn’t say much about the alternator but it does state that the regulator/rectifier is “SCR shorted/triple phase full-wave rectification”. The “SCR shorted” is the operative phrase.

When I first glanced at a schematic of a supposedly similar R/R that I found on the internet, I thought I knew how it worked. It looked like a 3-phase bridge rectifier, with switching SCR’s similar to the circuits in a household light dimmer. I should have looked closer because the light dimmer circuitry delays turning on the SCR each cycle to dim the lights. In other words, the more you delay turning on power to the light bulb, on each AC cycle, the dimmer the light. When the SCR is off, there is no current flowing.

Now with the R/R, full available current is always flowing. It starts out flowing to the battery, and bike systems, until their voltage levels reach the reference level (13.1V < Charging Voltage < 15.5V). Then the SCR’s shunt the alternator current back into the alternator through the bridge low side rectifiers (it can’t just turn off the current because a fly-back would occur in the alternator coils and they would arc or get even hotter from the current oscillating back and forth in them). When the SCR’s Short, the excess/wasted energy is then dissipated as heat. There is a voltage drop across the wires, the diodes, the SCR’s, and the connectors. Measure the voltage drop across any of those and multiply it times the current passing through it and that gives the power in watts that must be dissipated as heat by that component. The manual states that the alternator produces 0.438KW at 5000 RPM. Think about how hot a 100W incandescent light bulb gets and then put 4.4 of them together. The current is not continuously being shunted but if the battery is charged and there are few systems powered up then there is a lot of heat being dissipated by the R/R, the alternator, the wires, and the connectors connecting them.

I found this post by DirtFlier from 1/10/2012: “With the engine running, a normally functioning reg/rec is typically too hot to touch with an ungloved hand.” I assume he has touched a good one and it was hot. When I found my alternator wires were hot, I disconnected all of my accessories and the headlight. Not only did it not help, it made it worse because all of those items were no longer dissipating any heat, or using any energy. In fact, when the SCR’s short, the alternator sees the highest load possible, except for during a malfunction like a shorted alternator wire.

Control systems for automation equipment will shunt left over energy through external high wattage resistors called “braking resistors” so that the controller doesn’t overheat. Unfortunately, these R/R’s don’t give you access to the connections between the SCR’s and the diodes which is where the resistors would need to be inserted in the circuits. To make the situation even worse, the new R/R I installed uses FET’s instead of SCR’s. These FET’s supposedly have a lower forward voltage drop than the SCR’s. That makes the R/R run cooler but forces the alternator wires, connectors, and alternator to get even hotter. I cannot touch the crankcase cover for more than a half second it is so hot… but the R/R is cool.

Now I am going to hook everything back up and get serious about voltage and current readings and go from there. I’ll post what I learn and then get back to the MIL 8 issue again.

Sorry for the novel,
Mark

IMG_2472.JPG
 
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Now back to the alternator wires overheating. I finally realized that the alternator and regulator do not operate the way I would have expected them to. The alternator has no field coil and therefore it’s output cannot be varied, other than by varying the RPM. It basically puts out maximum current and voltage based on the RPM, although the load from the bike’s systems and accessories has an effect, it may not be what you might expect. The service manual doesn’t say much about the alternator but it does state that the regulator/rectifier is “SCR shorted/triple phase full-wave rectification”. The “SCR shorted” is the operative phrase.

When I first glanced at a schematic of a supposedly similar R/R that I found on the internet, I thought I knew how it worked. It looked like a 3-phase bridge rectifier, with switching SCR’s similar to the circuits in a household light dimmer. I should have looked closer because the light dimmer circuitry delays turning on the SCR each cycle to dim the lights. In other words, the more you delay turning on power to the light bulb, on each AC cycle, the dimmer the light. When the SCR is off, there is no current flowing.

Now with the R/R, full available current is always flowing. It starts out flowing to the battery, and bike systems, until their voltage levels reach the reference level (13.1V < Charging Voltage < 15.5V). Then the SCR’s shunt the alternator current back into the alternator through the bridge low side rectifiers (it can’t just turn off the current because a fly-back would occur in the alternator coils and they would arc or get even hotter from the current oscillating back and forth in them). When the SCR’s Short, the excess/wasted energy is then dissipated as heat. There is a voltage drop across the wires, the diodes, the SCR’s, and the connectors. Measure the voltage drop across any of those and multiply it times the current passing through it and that gives the power in watts that must be dissipated as heat by that component. The manual states that the alternator produces 0.438KW at 5000 RPM. Think about how hot a 100W incandescent light bulb gets and then put 4.4 of them together. The current is not continuously being shunted but if the battery is charged and there are few systems powered up then there is a lot of heat being dissipated by the R/R, the alternator, the wires, and the connectors connecting them.

I found this post by DirtFlier from 1/10/2012: “With the engine running, a normally functioning reg/rec is typically too hot to touch with an ungloved hand.” I assume he has touched a good one and it was hot. When I found my alternator wires were hot, I disconnected all of my accessories and the headlight. Not only did it not help, it made it worse because all of those items were no longer dissipating any heat, or using any energy. In fact, when the SCR’s short, the alternator sees the highest load possible, except for during a malfunction like a shorted alternator wire.

Control systems for automation equipment will shunt left over energy through external high wattage resistors called “braking resistors” so that the controller doesn’t overheat. Unfortunately, these R/R’s don’t give you access to the connections between the SCR’s and the diodes which is where the resistors would need to be inserted in the circuits. To make the situation even worse, the new R/R I installed uses FET’s instead of SCR’s. These FET’s supposedly have a lower forward voltage drop than the SCR’s. That makes the R/R run cooler but forces the alternator wires, connectors, and alternator to get even hotter. I cannot touch the crankcase cover for more than a half second it is so hot… but the R/R is cool.

Now I am going to hook everything back up and get serious about voltage and current readings and go from there. I’ll post what I learn and then get back to the MIL 8 issue again.

Sorry for the novel,
Mark

View attachment 13207

Interesting reading there!
Two or three years ago I installed a 12v PC cooling fan onto the Reg/Rec to keep it cool during Summer commuting.
It is just held onto the outside of the Reg/Rec with a couple of cable ties and wired into the accessory circuit so that it runs all the time the ignition is on.
IIRC it only draws about 1/4 of an amp.

There is not a lot of natural airflow around the unit at low speeds.

Macka
 
This does make me rethink a few items. Also the service manual is not too helpful here either. It is very basic and the NT's charging system is also more basic than I realized (should have known, I have pulled the alt cover and at least seen the coils). I should have looked closer. I am now probably going to have to monitor my R/R temp out of curiosity, I don't recall noticing it that hot in there.

Brad
 
The manual states that the alternator produces 0.438KW at 5000 RPM. Think about how hot a 100W incandescent light bulb gets and then put 4.4 of them together. The current is not continuously being shunted but if the battery is charged and there are few systems powered up then there is a lot of heat being dissipated by the R/R, the alternator, the wires, and the connectors connecting them.
Appreciate you taking the time to write that up.

The base load of entire electrical systems is probably in the 150-200 watt range at 5000 rpm and the battery charged. Adding up all the lights alone is over 100W.
55 headlight
5 marker light
10 for 2 tail lights
42 for 2 front turn signals that are on when not flashing.

FI is probably the next biggest load based on it has a 20A fuse (same as headlight fuse). Not sure what the Watts are, but in the range of 20-60 watts seems reasonable considering fuel pump, fuel injection, ECM.
The rest is pretty small, but there is the meter panel (with lights), and ignition system, ABS (maybe), and relays.

Even worst case the RR isn't dissipating full 438W of load, but ~300W is still significant. It interesting that if you have installed LED bulbs as a "use less energy" consideration you are actually making the RR heat up more. It may be a good idea to keep the load (and heat) in the bulbs.
 
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Hey Macka,
Love the fan. I may go back to the original R/R and install one.

Hey Brad,
I have not removed the left crankcase cover before. The manual says to place a pan under it to catch the oil. Are the alternator coils immersed in the engine oil?

Hey Dan,
Thanks for the power tally. That will be handy.

Thanks to all,
Mark
 
Mark,
The alternator cover is not too difficult to remove. I stripped the hex on the inspection cover while adjusting valves so I later replaced the cover and removed the inspection cover from the old one later.
I believe there is no gasket, it seals with 3 bond sealant. There is oil inside, the starter clutch and gears reside there also. The oil would cool/control the alternator temperature and would also make the cover very hot to the touch as you noted. If you need to remove your cover if the bike is leaned to the right not much oil will escape. The magnet on the flywheel is pretty strong so you will feel it pulling as you remove the cover with the coils on it.
Attached are a couple pics.

Brad
 

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I have measured the alternator coil resistances with an accurate milli-ohm meter. Randomly calling the yellow alternator wires x, y, and z, they read: x to y = 150.6 mOhms, x to z = 150.5 mOhms, and y to z = 150.8 mOhms. The manual states 0.1 to 1.0 Ohms which seems like a pretty wide range to me but mine are within the limits.

I couldn’t find any data on the coils inductances but mine read: x to y = 0.709 mHenrys, x to z = 0.746 mH, and y to z = 0.735 mH. I was not sure what to expect but at least they are all fairly close to each other.

I did not hi-pot them but with a multimeter they read infinity to ground.

Unless anyone has other info, I’m going to assume the alternator is good.

Thanks,
Mark
 
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