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Discussion Starter #1
I'm having a small issue with my 07 650. When I am running out on the highway I get a slight hesitation or flat spot when I make small throttle changes. I also get little stumbles when I am holding a steady throttle with rpms between 4,000 and 5,000.

I stripped the plastic off it and started running test on the ignition system. Everything was checking out OK until I started testing the throttle position sensor (TPS). I checked the adjustment using the dealer mode and it showed to be OK. I then went to the C14 error code section to see what the readings from the sensor should be. That is when I became totally confused.
Either my manual is messed up or my TPS has gone completely.

The first test of input voltage on the plug coming from the ECM came out good. I am getting 5.1 volts between the red wire and ground or the Red wire and the Black/Brown wire. That is inside the 4.5 V to 5.5 V range. On the plug to the sensor the continuity test between the yellow wire and ground was good.

When I moved to check resistance in the TPS is when things went off. First problem was the color coding on the wires. The manual says I should have a yellow wire and a green or red wire on the sensor plug. The yellow wire I have but the other two wires are blue and black. The blue wire on the sensor plug lines up with the red wire on the ECM side of the plug so I decided that was the one I should use.

The manual says it should have approx 1.1 ohms resistance throttle closed and approx 4.2 throttle open between the two wires. I'm showing 4.4 throttle closed and 1.9 throttle open. The manual says with the key on I should be getting approx 1.1 V throttle closed and approx 4.3 volts throttle open. I'm showing 3.9 volts throttle closed and 1.7 volts throttle open. It's like my TPS is working backwards.

I decided to check between the yellow wire and the black wire and results were similar although they varied a few tens on the readings. They still appeared to be backwards.

I was surprised that I did not have a C14 FI code. I checked the manual on what sets the code. It said that code would only be set if the sensor voltage was outside the range of 0.2 volts to 4.8 volts. Although I seem to be getting backwards readings they are within the acceptable range so no C14 code.

I'm still using the manual I bought for my 05 even though I have an 07. I do have copies of the blue pages that are suppose to show differences between the two years manuals. I can't find anything in those pages that show any differences in the test procedure or the wire color coding.

Now to my questions.

Has anyone else ever check the readings on their TPS. If so which wires did you check between and what readings were you getting throttle open and closed.

Could someone with a newer manual check theirs and see if the procedures for checking the TPS are still the same. In my manual the pages I am looking at are 6-31 and 6-32.
 

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I have manual # 99500-36116-03E manual says yellow green and red .

TheReaper!
 

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Discussion Starter #3
That is newer than mine. Mine has part number 99500-36111-03E.
 

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Discussion Starter #5
I've been doing some online research on TPS problems and symptoms. I found a GSX-750 rider whose bike was acting just like mine. Bogged down with small throttle changes and had trouble holding a steady rpm. Problem turned out to be the TPS. Guess what, the GSX-750 uses the exact same TPS as the Burgman 650. In fact Suzuki uses that 13580-40F20 sensor on a bunch of bikes along with some outboard motors and ATV's.
 

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Discussion Starter #7
I checked the adjustment yesterday and the little bar was right in the middle.

I've about decided to go ahead and order another TPS. One last thing I'm going to do first is drive into Robin's place in Dallas this evening and check what resistance readings I get on her TPS. If I get the same readings on hers as I do on mine I will go back to looking for something else that might be causing the issue. I've sent her an email to see if she will be home.

That is unless there is someone who can check the readings on their TPS and see what they get. I'm pretty sure the plug can be reached just by removing the maintenance access cover. You should be able to see it through the two holes at the front right above the throttle bodies. It's a 3 wire that goes across right to left and the plug should be visible through the left hole. All you have to do is undo the plug then use a multi-meter to take ohm readings between the yellow and blue wires on the male side of the plug. Readings would need to be done the throttle closed and again with the throttle open.
 

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Buffalo,

I just went through my entire service manual which has the add-on blue pages for the 05 through 08 models, there doesn't seem to be any new instructions on how to check the TPS.

here is a picture of the 07 TPS from the blue pages in the service manual:



I checked my TPS sensor position when I replaced my throttle assembly and it showed that it was positioned normally.

i haven't played with adjusting it.

but considering the high mileage on your scoot, it could be that the sensor has gone bad, replacing it should be pretty easy.

Suzuki does seem to be using a lot of the same parts/sensors on a lot of its bikes, the GSX models use the same water pump too.

all the best....
 

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Discussion Starter #9
Thanks for looking LeDude. In the picture you posted the wire that has P/B on it is the one that ends up connecting to the yellow wire on my TPS. The top one of the three wires is the red one from the ECM and it goes to the blue wire on my TPS. The center wire is the B/Br wire coming from the ECM and it goes to the black wire on my TPS. It is also the ground wire for the ECM. That is why I am pretty sure that I should be checking readings between the yellow and blue wires on my TPS.

Biggest problem with replacing it will just be getting my big hands in to do it. With the throttle bodies still on the engine in the frame the hole to work through is pretty tight. I looked at it last night and one of the frame rails covers about half of the sensor. I'll have to get in there and scribe a mark on the old sensor and the throttle body for alignment then transfer that mark to the new sensor so I can get it on in the right position. That should give me a good starting point for final adjustment.
 

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The sensor color codes you are seeing seem to correspond to the colors in the shop manual for the C50 Boulevard. On that bike RED is VCC (+5VDC) and connects to the Blue sensor wire, B/Br appears to be the Ground connection and connects to the Black sensor wire. Bl/B is the TPS output and is the Yellow sensor wire.

Based on this I would expect you need to be measuring from the yellow (+) to the Black (-)
 

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MEasuring it the way you did would result, oddly enough, in readings that seem to be opposite what is in the manual.

Does your meter have any typoe of analog display (bar graph or such). If so you might try to see how smoothly the sensor output follows the throttle plate movement. Sensor might not be completely off but might have dead spots in the span.
 

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Discussion Starter #12
Thanks for the info Chapman128. The C50 uses the same TPS part number as the 650 so what you mention should be applicable. However I think I did do a test between the yellow and black wires with pretty much the same results. I will go check it again though.

My meter does not have any kind of analog display.
 

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Discussion Starter #13
I went out and checked again between the yellow and black wires. I got numbers that made more sense but it still looks like I have a problem. I think what happened yesterday morning was that I only did a check between the yellow and black wires on closed throttle. When I saw a reading around 4 I assumed it was working just like between the blue and yellow wires so didn't bother to check wide open throttle.

When I did a check at wide open throttle I got a steady reading of 4.41. A little above the 4.2 spec but within reason. When I did a reading on closed throttle I could not get a consistent reading. The meter gave a different reading each time I checked it. They varied from as low as 3.18 to as high as 4.11. All the readings were well above the 1.1 spec.

I clicked on my throttle lock so I could check various throttle settings. I did a check at about 1/2 throttle and had a reading of 2.86. I did a few more test at different throttle settings and also got steady readings until I hit one spot where it went haywire. The numbers bounced up and down from as low as 0.9 all the way up to 11.35 and would not hold steady. I changed the throttle setting a little and it went to a steady reading of 3.03. I tried to find that one spot again but could not hit it. However the throttle was at about the same spot where it would be when I was having the surging issues cruising at around 60 mph.

Looks like at best I have a TPS that is starting to fail so I should go ahead and replace it. Don't know if it will fix my problems but it can't hurt anything except my pocket book to find out.

With the readings I am getting at closed throttle I don't know why it is idling OK. I guess the ECM sees the readings from the other sensors that show I should at idle and ignores the TPS sensor.
 

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OK sports fans, I think you got it. :blob4:
On all the input sensors, both being in range and a smooth up and down reading are critical.
If you get any bounce in the resistance or flat spots, it will cause all kinds of problems.
I have not had any problems with mine but this is based on years of working with electric forklifts in warehouse setting.
The man up electric forklifts have all kinds of sensors, both input and feedback. If you get any fluctuation in the readings, either a flat spot or a up and down jump, the equipment will code out and not work. Even if the high and low readings are in range, it will still code out.
I would go with a new TPS.
.
 

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Craig, sometimes an old things are not bad. :p I have about 4 digital VOM's and 3 analog ones. At work I use analog everyday to check telephone cables. To do a sensor sweep, most times you need an analog VOM.
 

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Discussion Starter #17
I actually have an analog meter but it is 48 years old and doesn't work worth a hoot anymore except on the volt setting. I bought it when I was a teenager building hot rods.
 

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At a guess, I'd bet the sensor is nothing more than a potentiometer. You could probably skate by with some contact cleaner while waiting for a part. Then again, I just looked and Ron Ayers has the part for about $160. For that much I'd hope there's something more in there than a pot. I hit it with some cleaner anyway. If that part's been around since the dawn of time, I don't think they were doing much with micro machining in those days.
 

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As Chatman128 says, the sensor is a poteniometer, it works like a radio volume control - but with a narrower span - and the wiper sweeps from practically zero ohms to maximum. As long as there is not a physical break in the track a few rotations in a switch cleaner (WD40 or similar) should clean it out ok.
(I know some people discourage using WD40 for electricals but I have always had great results using it.)
 

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Discussion Starter #20
I've already got a new one on order so I likely won't mess with trying to make this one work.
 
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