Anatomy of Gen III Fly By Wire TPS

[Fred W]

Ugh...

Did my 20k mile service this morning in prep for EOM in 2 weeks. Since I had the time I lifted the tank and checked the TBS (which was only off a tiny bit) which exposed the TPS on the left end of the throttle body. My TPS has a code of 4314E and a blue dot also. Not that I've noticed any problems caused by it (yet), but that would appear to put me into the affected series based on the single confirmed sample we have so far.

edit: This can't be a date code. Week 43 would be in October and I picked my bike up in September of '14.

My bike's VIN ends in 000457

 

[ionbeam]

edit: This can't be a date code. Week 43 would be in October and I picked my bike up in September of '14.

Ahh, that's good info. The week/year date coding is almost universal in the electronics field. It just seemed to fit so well into that pattern. Time warp?

Original post has been edited.

 

[RaYzerman19]

V-max forum seems to have nothing much going on with TPS issues.

Date codes can take many forms and sometimes are codes known to the supplier..... I could speculate 4314E might be 2014, 31st day of April, line E. Who knows.

Yamaha will most likely track warranty numbers and cost, we don't know tip levels..... so far we have one which isn't in their database and one suspect TBD. Relatively speaking, those aren't going to hit any radar that would drive a change. Only time will tell if we get more failures...... it would help if the failed one made it to Yamaha, but as has been said, it's sample size one (to the best of our knowledge). An actual dealer warranty claim/repair helps, but again, we'll have to see some numbers.

 

[Fred W]

In the photos (and on mine in situ) I do not see any markings indicating the part manufacturer, just the code and blue dot. I also looked back at the 1st Gen TPS recall and there was no manufacturer info released in that campaign either.

Oh well, we'll just have to stay on top of this going forward.

 

[RossKean]

If I had a Gen III, I think I might just keep a spare in the tool kit.

 

[Uncle Hud]

As an extra data point, I have a little over 41,000 miles on my Gen3 2015. No herky-jerky throttle response. Yet.

I also try to operate the throttle smoothly, so perhaps the gentle "backwards" throttle movement doesn't cause the wipers to gouge the resistive surface as harshly. (?)

Notes:

1. I don't hot-rod, and by that I mean probably fewer than 12 ionbeam drag racing starts in 24 months of ownership.
2. Shouldn't matter, but well over 95% of my miles have been in T-mode. (Goes hand-in-hand with note #1.)

 

[mikerider]

If I had a Gen III, I think I might just keep a spare in the tool kit.

I guess it's still better than carrying a final drive in the tool kit...

How easy/hard to replace the TPS? Is this something that can be done in the parking lot with simple tools?

 

[RossKean]

Based upon the parts fiche, the Accelerator Sensor A (1MC-85884-00-00) appears to be very similar to the TPS. I wonder if the construction is essentially the same and if it is also subject to premature wear and failure? I suppose that this might be a possibility if a TPS replacement doesn't fix things. I assume it would have a similar effect - maybe even worse!

 

[ionbeam]

To access the Accelerator Sensor the entire throttle body rack has to be removed. This is so much work that the Accelerator Sensor shouldn't be considered when troubleshooting

It's interesting to note that the schematic for the TPS and Accelerator Sensor shows two circuits in each sensor, but in the Electrical Components section of the FSM, it only tells you to check only one circuit in each connector. Worse, the FSM only has you check the overall resistance of the sensor and does not instruct you to check the wiper resistance of either sensor.

 

[RaYzerman19]

You guys gotta relax..... first of all it's a gradual failure. Where's the evidence to say we have an epidemic and we have to carry spares? We have 4 model years on the road, one report and one maybe. What if the unkown problem turns out to be a servo, are you gonna carry a spare throttle body?

 

[ionbeam]

You guys gotta relax...What if the unkown problem turns out to be a servo, are you gonna carry a spare throttle body?

Ask Bill Lumberg about that....

 

[Viper Pilot]

LMAO!!!

 

[Bill Lumberg]

As we all know, the rarity of a particular problem is not usually appreciated by the one experiencing the problem.... I had a gent PM me last night who had the same problem, with the same Yamaha fix. They were just lucky enough to get the part shipped from Gojira much more quickly than I have been able to.

 

[mcatrophy]

...

if (mod(voltage1-voltage2))>ALLOWED_TPS_DIFFERENCE) {

error(TPS_ON_THE_WAY_OUT);

}

What's that funny stuff? Write that in assembler and I might understand what you are saying.

...

Well, if you want to go archaic in coding (as well as off topic), let's go archaic in microprocessor as well, try Motorola MC6809 assembler:

* subroutine to check TPS voltage differences
TPS_CHECK_VOLTAGE_DIFF
LDD TPS1_VOLTAGE pick up the measured voltage from TPS #1
SUBD TPS2_VOLTAGE subtract the measured voltage from TPS #2
BPL TPS_DOFF_POS branch if result is positive
COMA negate D by complimenting A ...
COMB ... and B ...
ADDD #1 ... and correct
TPS_DOFF_POS SUBD #ALLOWED_TPS_DIFFERENCE subtract the maximum allowed difference
BMI TPS_NO_VOLTAGE_ERROR if negative result, diff not too big, branch round
LDD #TPS_ON_THE_WAY_OUT else get the appropriate error
JSR ERROR call the error routine
TPS_NO_VOLTAGE_ERROR
RTS and return

I would presume the ECU code was written in something more modern than that, and the CPU would be a slightly more modern processor, though I don't know what.

 

[ionbeam]

I wouldn't be surprised to see that he ECU has modern DSPs which are real workhorses. Something that Mcatrophy knows a little about

Yamaha brags that the response of the ECU to implement FI actions is 1mS of faster (1 thousandth of a second). That assembler code is a fond memory of days past, and a reminder that the future can be better.

In any case we are talking about the ECU having the information to set a TPS error code but for some reason is only programmed to flag OPEN, SHORT and STUCK failure modes. It seems an oversight that the ECU can't also set a voltage anomaly failure code too. The '13 and up does have data logging capability which should clearly show TPS error voltages. Because the ECU FI routine reacts to the voltage drop-outs is proof positive that the ECU is receiving the erroneous voltages. If I were to guess why Yamaha people haven't been flagging failing TPS via data logging is either the Yamaha Diagnostic software doesn't offer a CLICK-IT report for the TPS voltage or the tech isn't trained well enough to know what he is looking for. I have seen YouTube videos (groan, ya, ya, I know...) of Yamaha techs explaining FI issues, at least some Yamaha Techs seem to be well trained.

 

[audiowize]

On a fishing trip to Alaska some years ago, the TPS on a 3 month old Volvo diesel gave up, with the wiper on a ten turn pot just giving up on life. The only solution that I have ever liked for this is to go with an optical encoder, but damn are they expensive!

 

[@rjen]

Interesting reading this. On august 26, 2016 one of the Technical expert in our FJR community (NL) reported that Yamaha has released an updated TPS...

It is now supposed to be electronic rather than mechanical adn should give a more consisent signal to the ECU (his words not mine)

New one on the left, old on the right.

3P6-85885-00-00: Yamaha Throttle sensor assy 81,99 euro

 

[@rjen]

Never mind that. This was related to the previous model. Sorry.

 

[Fred W]

Still of interest as TPS devices in general are of the same type and have the same failures more or less universally. It would be interesting to learn what the new "electronic" device is. Of course the old device was electronic as well, but we know what your friend was getting at.

Some sort of a digital, optical encoder would likely be more accurate and less prone to the type of failures the rheostats we now use would be, but that would require a completely different ECU with an input that could track and digest the encoder pulses.

 

[Fred W]

Dredging this old thread up because I seem to finally be affected by the throttle position herky jerky. I’m sitting at 65k miles on the 2014 (miles are being split with three other trusty steeds).

My present symptoms are slightly different from those previously shown. For one thing, the herky jerky throttle happens only when the bike is cold. The jerkiness is right off throttle stop, but only when cold. Most other reports, and my own prior experience, is that TPS’s go wonky when they get real hot. Mine actually seems to improve after everything comes up to temp.

I’ve gone through the diag screens, and have noticed something happening that I don’t recall from prior messin’ around: At rest, both of the TPS signals (diag #1 and diag #13) show good nominal numbers near the center of the acceptable range. But, as soon as I roll the throttle off of the stop I hear a “click” from down below, and the diag numbers increment by about 4-5 counts. This is 100% repeatably, and is occurring on both TPS signals.

I’ve also looked at the APS diag locations (14 and 15) and they also have an increment at the clicking sound, but only by 2-3 counts. At first I thought the click was a relay, but I can’t find any switches or relays that monitor the throttle home position. So now I think that what I’m hearing the rapid twist of the throttle servo motor when one of the sensors glitch.

So now I’m looking at a chicken vs. egg dilemma. Is this caused by a bad spot in the APS (command signal) or some sort of feedback to the APS by the TPS?

My gut instinct is that this is an APS problem. I’ve never felt any issues with cruise control active, but that is usually after everything has warmed up. And I can’t come up with a good reason for the APS signal to glitch at all when the throttle motor apparently jerks.

I’ll lift the tank soon and do more eye-balling of what happens during these diagnostics, and also put a volt meter on those sensors to see if I can see anything, but past experience is that it’s really hard to catch one acting up.

 

[RossKean]

So now I’m looking at a chicken vs. egg dilemma. Is this caused by a bad spot in the APS (command signal) or some sort of feedback to the APS by the TPS?

Tough call. Maybe you can remove the parts and put an ohmmeter across them to see if they test as they should (assume specs are available). Might be able to tell if there are any dead spots as you move the wipers. About $200 for the two sensors...