@TTUdude

Okay hopefully this is simple-ish.

Code 42, CEL on, no speedo, puff of smoke.

Most likely it's the pesky neutral switch, but it could be a wire between the speed sensor and the motor.

Check the e-copy of the service manual chapter 6 for how to read error codes in memory. Let's be certain its just the one Code.

Then run Diagnostics (also chapter 6). For this, raise the back wheel off the ground and stabilize.

If Diagnostic Code 07 displays numbers from 0 to 999 incrementally rising each time the rear wheel is manually spun (off ground and stable) then your speed sensor system is okay. This can be done by pushing the bike forward, but be certain you are safe and have plenty of room to go straight so no chance of dropping the bike.

Then, if Diagnostic Code 21 displays 'on' when the bike is in neutral, and 'off' when the bike is in gear, then it's working.

These can both be done same time in sequence.

For clarification, Code 42 causes the ECU to assume the bike is in 5th gear as a default method of allowing the bike to run with a speed sensor issue, so we cannot arbitrarily take it out of the test. This could explain smoke. But it would point to the speed sensor (or its wire on the motor-side, which will make sense when you are doing the work if it goes that way). Because you don't see smoke anymore, it points to the neutral switch being the trouble. We will see.

If it were me, I would check Code history, and I would run both tests to verify which is the culprit. Then I would use Chapter 7 to look inside their associated electrical plugs. Only then would I dig further into the wiring on the bike beyond these easy checks.

 

Thank you so much for your reply! You're incredibly knowledgeable!! I'll be running the tests and checks this week and will get back to you! It's so amazing how much knowledge you guys have!!

 

So I just ran the diagnostics as suggested. Went in diagnostic code 07, the numbers do not change when manually pushing the bike. I assume the motor does not need to be running in order for this check to work? The other code 21 says 'on'. So this mean that my speed sensor system needs to be addressed, I guess... I hope that's not too hard of a fix.

 

I saw some old posts talking about and indicating where the speed sensor is but all those photos seem to be dated and no longer available

 

No worries. The motor will not start while in Diagnostics mode. Sort of a safety and practicality thing.

For fun, on 21 did you shift into gear then back out of year and watch for the related 'on' and 'off' to change in the display?!

Just to be safe. When you entered 07 and operated it, did at least a zero '0' display in the correct window? I should go check but it might be the odometer display that should have a 0 until the rotations cause the shaft to rotate past the sensor inside the Motor/Trans case. Turning the rear wheel forward turns the belt which turns the front pulley which turns the shaft and right side gears and that shaft etc and finally the sensor picks-it-up inside the case.

If the 0 displayed and you checked each step in operating 07 then the first thing I would do is check the manual for the electrical connector for the speed sensor. Plus follow the wires looking for damage. Hall sensors are robust and seldom fail. If no wire or plug damage then there is also a test in the troubleshooting section. Sorry I'm not near my manual.

Candidly, the first time I played with operating this diagnostic item it did not work. I did it while I had the rear off the ground anyway. I re-read and re-tried and it worked. I honestly don't think I did anything differently the second time. But I guess I must have.

Someone here told me they pushed the bike in neutral and got numbers so I believe that works.

Obviously the sensor could be bad, or the wire broken where it enters the sensor. But its not very common. Its more commonly corrosion in a plug, or wire abrasion in between.

 

I just checked all my connectors and everything looks really nice and clean. I did try the diagnostic code 07 again and It still read 0. I'll have to look for that troubleshooting section if there are no wire plug issues. Thanks so much for your guidance on this!

 

I went ahead and ordered a new speed sensor from partzilla. Hopefully it will be in a few days and I can try to tackle this project on my own without taking it to the shop. My biggest question is, where is the speed sensor? I get a strong impression that it's behind the oil tank and I'm trying to figure out where and how to access it. Do I go from the exhaust side or the clutch side. Do I need to remove anything particular in order to be able to see it and work on it? I know there was a thread years ago that had pictures but unfortunately the pics don't exist 😤
If I'm able to get to things and work on it I'll definitely take pictures and update for future folks like myself.

 

Okay. I guess we will jump ahead.

The speed sensor is a brute to replace. Plus, it's a robust device, but it seems like most of the time when it fails its the speedometer that causes the failure. Maybe my perception over the years is skewed. But it seems that way to me, meaning you need to test the speedometer too. If you don't then you might go through the process of replacing the speed sensor only to have if cook again. So you really really really need to test the speedometer, and test the speed sensor at its three wire plug. I'll get the info for you.

There are a couple questions first.

When you are out riding, and you turn on a turn signal, does it auto-cancel or does it just stay blinking even past the distance in the manual (something like 150 feet)? Read up on the auto cancel function. If the speed sensor is working and if your bike has the stock Denso flasher, then it will auto-cancel to spec.

When you first turn the key on, does the speedometer sweep in the start-up test?

Thanks.

 

Okay. I guess we will jump ahead.

The speed sensor is a brute to replace. Plus, it's a robust device, but it seems like most of the time when it fails its the speedometer that causes the failure. Maybe my perception over the years is skewed. But it seems that way to me, meaning you need to test the speedometer too. If you don't then you might go through the process of replacing the speed sensor only to have if cook again. So you really really really need to test the speedometer, and test the speed sensor at its three wire plug. I'll get the info for you.

There are a couple questions first.

When you are out riding, and you turn on a turn signal, does it auto-cancel or does it just stay blinking even past the distance in the manual (something like 150 feet)? Read up on the auto cancel function. If the speed sensor is working and if your bike has the stock Denso flasher, then it will auto-cancel to spec.

When you first turn the key on, does the speedometer sweep in the start-up test?

Thanks.

I agree and appreciate your approach to addressing this issue! Start small before taking on big problems that might leave you back and square one.

I changed out the flash relay on the bike to address the hyper flash issues I was having last year and that killed the auto cancel function. So unfortunately I can't trouble shoot that way unless I happened to hold on to it- I'll search around, but doubtful.

The speedometer does do its start up sequence. One this I'll check when I take the bike out today is see if I'm getting any change on the odometer, since that should indicate tracking or not?

 

Keeping this separate from the above:

I borrowed this info from an earlier post. I'll reference later, but need to gather everything. I'm providing this info because it's accurate, and you're going to need to know wassup in order to become convinced to test everything first. The speed sensor is the most challenging electrical repair on the bike.

Borrowed text:

"The speed sensor is located between the frame and the transaxle just aft of the nuetral switch and behind the oil tank.

Everything under the seat has to be removed, the battery box, left side cover, fuel pump, fuel tank, and all connectors have to be disconnected.

Once everything is out, all the wiring running down the frame has to be removed from the plastic clips and pulled aside.

There is one allen head bolt that holds the sensor in the case. Even with everything out of the way, you can barely see the sensor, pulling it out and getting it out of the frame takes a little twisting, flipping and lots of patience."

More later. I need to assemble things and find pictures.

This work is one of just a few tasks that I almost recommend having a Yamaha dealer shop do. If you have smallish sized hands, basic automotive repair experience, a simple electrical meter, and hand tools, and if you know how to find the release pins on some electrical connectors, then it's possible to do this in a long day. Take pictures as you go along so you can reassemble correctly. The trouble is, it takes doing it once to understand everything. So those who do it are to some extent on their own. Looking at its location on the bike, holy cow.

 

Keeping this separate from the above:

I borrowed this info from an earlier post. I'll reference later, but need to gather everything. I'm providing this info because it's accurate, and you're going to need to know wassup in order to become convinced to test everything first. The speed sensor is the most challenging electrical repair on the bike.

Borrowed text:

"The speed sensor is located between the frame and the transaxle just aft of the nuetral switch and behind the oil tank.

Everything under the seat has to be removed, the battery box, left side cover, fuel pump, fuel tank, and all connectors have to be disconnected.

Once everything is out, all the wiring running down the frame has to be removed from the plastic clips and pulled aside.

There is one allen head bolt that holds the sensor in the case. Even with everything out of the way, you can barely see the sensor, pulling it out and getting it out of the frame takes a little twisting, flipping and lots of patience."

Reference:

Speedometer pickup location ????

Where is the speedometer pickup loacation at? I looked today for about 30 minutes and could not trace it down. Thanks.

www.rswarrior.com

This work is one of just a few tasks that I almost recommend having a Yamaha dealer shop do. If you have smallish sized hands, basic automotive repair experience, a simple electrical meter, and hand tools, and if you know how to find the release pins on some electrical connectors, then it's possible to do this in a long day. Take pictures as you go along so you can reassemble correctly. The trouble is, it takes doing it once to understand everything. So those who do it are to some extent on their own. Looking at its location on the bike, holy cow.

 

Keeping this separate from the above:

I borrowed this info from an earlier post. I'll reference later, but need to gather everything. I'm providing this info because it's accurate, and you're going to need to know wassup in order to become convinced to test everything first. The speed sensor is the most challenging electrical repair on the bike.

Borrowed text:

"The speed sensor is located between the frame and the transaxle just aft of the nuetral switch and behind the oil tank.

Everything under the seat has to be removed, the battery box, left side cover, fuel pump, fuel tank, and all connectors have to be disconnected.

Once everything is out, all the wiring running down the frame has to be removed from the plastic clips and pulled aside.

There is one allen head bolt that holds the sensor in the case. Even with everything out of the way, you can barely see the sensor, pulling it out and getting it out of the frame takes a little twisting, flipping and lots of patience."

More later. I need to assemble things and find pictures.

This work is one of just a few tasks that I almost recommend having a Yamaha dealer shop do. If you have smallish sized hands, basic automotive repair experience, a simple electrical meter, and hand tools, and if you know how to find the release pins on some electrical connectors, then it's possible to do this in a long day. Take pictures as you go along so you can reassemble correctly. The trouble is, it takes doing it once to understand everything. So those who do it are to some extent on their own. Looking at its location on the bike, holy cow.

😵😵😵
I love being able to do the work myself, but I don't think I have the ability to tackle this ask based on the information above!! The bike is still do for it's recalls so I may just bite the bullet and get it all addressed at once 😩
Certainly sounding more like a winter project when i have the time and patience to do it myself, sadly.
I've got sizable hands and have a smaller work space than I used to for maintenance now. Looks like it's off to the shop.

Thank you for your wisdom and help in this matter!!! I'll make a note to follow up and share what the shop says was the issue once I get it back!

 

Understandable.

But be certain they investigate the speedometer too. Doing that, it tips them they could sell you a new speedo too. So you should at least observe so can answer the remaining prior question. Then we might walk you through testing the two devices. At least you will have some knowledge before going in.

Speed Sensor see 6-7 item 42 and 7-60 and 2-23 and 2-38 and 2-42 and 2-45 item 16 (similar to supplements below). Then use page 5-5 for the generic approximate speed sensor location. Use prior info to dial-in true location. Take into account results of Diagnostics results but still meter the connector plug as shown.
Also see 2006 supplement page 9 items C and G plus page 11 item 18 and page 16 item U.
Also see 2003 supplement page 5 item C and page 8 item 16 and page 10 item P.

Speedometer see 7-3 for coupler and be familiar with 1-30 and 1-31. See 3-5 to disassemble. More speedo info later. The manual is less than comprehensive. I hopefully still have some info on my computer.

Also:
ECU pin 18 receives the speed sensor's signal, it could be corroded who knows. I'm uncertain if this is likely to play a part.

I'm added the earlier reference link into my post above as mentioned earlier.

 

Wow! So much information! I'll have to slowly go over this in the next week or 2. Thanks so much!! I can confirm- went to get my inspection done just now and the odometer isn't showing the miles I've traveled (stuck at 3579). Don't know if that helps deduce anything, but wanted to share.
Thanks again!

 

@V8mustang_gt also the OP hasn't been on in almost 2 years. What kinda problems are you having as we need more background on what is happening with your situation.