[onewizard]

Vehicle Down Sensor

Hi guys,

Yesterday my bike (V650 2014) died on me while riding and now it doesn't want to start again. Well it starts but cuts out after a few seconds.

I checked the fueling, ignition coils and battery. All are fine.
The only thing that influences is if I disconnect the vehicle down sensor. My fuel pump cycles longer while the sensor is disconnected and the bike runs 5 seconds when it's disconnected.
When I connect it again, the bike won't start up again.

Is the sensor at fault? Or should I look somewhere else?

Best to read this older post, there is a test for this in the manual.
https://www.kawasakiversys.com/forums/170-technical-discussion-v-650/118866-engine-not-firing.html

 

[onewizard]

Thanks for the link, I already read it completely and tested a few things.
The voltage to the sensor is OK, but I have no way of reading the output voltage.

However when the sensor is plugged in, my fuel pump cycles 1 second and then stops when I turn my ignition on. The bike won't start with the sensor connected.

With the sensor disconnected, the fuel pump cycles 3 seconds and then the bike starts for 5 seconds and cuts out.

So should I just get a new sensor?

There is no out of circuit test, however I have drawn out what I think the internal connection looks like. Since you have followed 3-59 to 3-60 of the service manual, the BL ( blue) positive and BR/BK ( brown with black tracer ) negative are the input terminals and the center Y/G ( yellow with green tracer) is the output to the ECU.
Take the sensor out of the bike, it mentions not to drop it. Measure the input terminals ( outside terminals ) using a ohm meter, this measurement should be stable irregardless of what position you are holding the sensor.
Next measure from what would be the BL terminal with the sensor vertical to the center what would be the Y/G, note that reading, repeat for the BR/BK to center terminal , record your readings and post.

Since the ECU is looking for a positive 3.55 to 4.45 VDC input, you could try using a 100,000 ohm resistor between the BL and Y/G , try starting the bike and see if it runs for more than 5 seconds ( FYI you do this at your own risk and if it works you need to replace the sensor).

 

[onewizard]

Thanks for the help man!

These are my readings, tested with an Ohm meter on 20k setting:
* input terminals together: 16.03 stable
* BL terminal to Y/G terminal: 13.03 , sometimes 13.02
* BR terminal to Y/G terminal: 3.02 , sometimes 3.01

If all those readings are vertical, 3.02 K ohms ? that is 3,002 Ohms. That is what the BL to Y/G should be when vertical, did you try lightly shaking side to side and retesting vertical ? At this point it appears NFG ( not for good >)

 

[onewizard]

Sorry I mistyped. I switched BL and BR.

So readings are:

* BRterminal to Y/G terminal: 13.03 , sometimes 13.02
* BL terminal to Y/G terminal: 3.02 , sometimes 3.01

Sorry!

The manual calls for a special pin probe, I have used straight pins. Years ago there was a piecing probe made by Fluke, not something I encourage but two ways of doing this, one to take a straight pin and bend it, trying to slip into those terminals and follow the manual. The second way would be to take a straight pin or needle and pierce the Y/G wire ( about 1 inch from the connector , tape up later, if concerned use silicone and tape), connect your negative to battery negative, positive to Y/G pin , key on and note voltage.

One other thing, you may need to remove the seat/ tank mounting bracket and remove & check grounds, the ECU doesn't have a wired negative ground from the battery, but depends on the steel frame, many, including myself have found a corroded connection here on my 07, this is on the foot brake side of the bike just below and to the rear of the seat/ tank mounting bracket.

 

[onewizard]

Vehicle Down Sensor / Doing it's Job

Just pierced Y/G wire with sensor connected. These are the voltages:
* Sensor tilted: 1.043 volt (should be 0.65 - 1.35)
* Sensor dead vertical: 1.04 volt (should be 3.55 - 4.45)

So I guess it's time to order a new sensor?

Looks like the magic smoke escaped, thanks for going the extra mile. I would still check the ECU grounds, they are 18 to 20 gauge wires, approximately 2 on your model year, there may be more, I have no idea why Kawasaki uses the steel frame to power these connections. And judging by your findings you need a new one.:surprise:




FYI the ground on my 2015 even new was poorly done at the seat. I scotch brited and then used a copper based anti oxide coating that I have used for years in harsh environments ( gravel pit crushing plant , any connections , including fittings that don't get coated are like welded together in 3 months , the stuff I use is a T&B product called Kopr coat https://www.specialized.net/cp8-tb-thomas-betts-kopr-shield-compound-8-oz.html Jet-Lube, LLC. | Kopr-Kote Industrial - High Temp Anti-Sieze)

 

[onewizard]

ECU Grounds

Is the Ecu frame ground in the first picture circled in red? Of should it be somewhere in the second picture?

Thanks!

Looking at the photo, right side, you have the mounting bolts for the seat / tank bracket removed, just rear of the mounting bolt hole is a clear hole, if you look through that hole you should see the wires. Only way of accessing it is to use a piece of wood on either side of the rear of the gas tank, and remove the bracket, PITA to get at.

One other test I failed to have you make was to measure between the Blue and brown with black tracer while connected to the sensor, there is a remote chance the 5 volt power supply of the ECU has failed. I thought you measured the VDC of the input, however going back in the posts I couldn't find that, it should be around 5VDC while connected to the sensor. I have seen it where open circuit it shows 5 volts but under load much less.( connected to sensor it is a fixed value, far below 5 volts)
The sensor acts as a voltage divider, since whatever comes into the sensor as supply volts ,the input voltage will be equal to BR/BK & Y/G plus BL & Y/G . That is if you measured a input of 5 volts, with the sensor vertical you should get say 4 VDC at Y/G WRG ( with reference to ground) and 1 VDC from BL to Y/G. There could be a blocking diode in the output and also a fixed resistance . Since it is roughly 0.7 VDC in the manual difference, my guess is a blocking diode.

 

[onewizard]

That's great. I think there is no resistor/tension divider here. That's a great little mechanism to prevent wear and poor shock resistance otherwise found in variable resistors.

It looks like a hall effect sensor. The dented wheel would move in front of the tiny square chip (hall sensor with transistor I guess) and turn the base on, shorting to 1v instead of the 4v.

Still seems possible to hack a "always upright" hard wired version with a 3.3kohms + 12kohms...
Unless the chip actually sends a waveform like in garage door trip light sensors, to avoid unsecure hacks...
Someone would have to put an oscilloscope to see it in action, if the hard tension divider doesn't work.

Seeing a chip there make me think that it is not simple DC electronics.

I would check with a polarized magnet and a small steel screw driver, locate 1 or more magnets, identify if polarized ( one attracts one repels if 2) . Agreed, much more complex than resistors, if no magnet it could also be a proximity sensor.

 

[onewizard]

I did explain in post 24. If you want 4V out of 5V, the higher resistor need to be on the ground side. So exactly the opposite of what you wrote. 3.3kohms should be on the +5v (blue) side and center (yellow). To the casual reader, if you don't know what a tension divider is, stay away from electronics and the hacks discussed here. LOL!




Yeah, I gave it a fair 5+ seconds. Every test. With ignition off-on every test. I have not looked for "error codes" of any kind. Bike just ran fine (in neutral) in all cases. I suspect the ECU expects low vs high voltage (binary) and it may have a pull up resistor, so when disconnected, it shows as high voltage, thus thinks the bike is "upright". It makes sense that engineers would design to tolerate circuit failures like a broken cable or connector.

I intend to remove the dash upper cowling and go ride with the VDS disconnected, reconnecting if it fails/ Maybe tomorrow. Someone else can report results too (scientific method).

See post 26 , As I think I stuck my foot in my mouth here. Yes I make mistakes too

Voltage is equal to current times resistance. Supply positive is BL ( @5VDC) supply negative is BR/BK . Output is Y/G Total circuit R is 12K +3K = 15 K . Current is volts divided by resistance 5 VDC /15k = 0.00033 amps

Volts across 12 k resistor is 0.00033 X 12k = 3.96 VDC.
[/B]

To go one step further you could measure the current through the Y/G wire to the ECU. Take that current and calculate the resistance required to produce a 1 volt drop , say it was 1.3 milliamp current ( R= E over I) = ( 1VDC divided by 0.0013 amp) = a 769 ohm resistor @ 1/4 watt or less. Therefore you would only need one resistor. Big difference between a voltage divider and something to produce a series voltage drop on a fixed load.

 

[onewizard]

Colur coded and Accurate

Hi onewizard, I don't know how the discussion turned this way but I feel some anger coming my way. I trying to help. I have an electrical engineering degree so I think I thought I could actually help. I can move along if you really prefer so.

This below is what I tried. I simply pointed out that you indicated to put the 12kohms on the blue side which is wrong. I also assume the ECU input (yellow) is high impedance and doesn't draw any significant current but merely detects voltage, as any modern microcontroller input would. I tried to respect the hinted approximate 16kohms in other posts as a starting point.

Anyway. Here is my diagram. I'll shut up now.

Well when I screw up , I do a good job of it, eventually I will edit out my mistakes in the previous post. Many times when I had problems on complex circuits I would draw it out, this time I figured I was smart enough and my memory was good enough that I could do it in my head. So in the drawing, measuring across
the 12 K resistor will give approx. 4 VDC, the key is that the input to the ECU must be positive with respect to ground, therefore one side of that 12K resistor must be connected to ground.

So I was 100% wrong :sorry:

Also :thanx: for taking the trouble to provide a accurate drawing.

 

[onewizard]

Vehicle Down / Tip Over Sensor / Testing/ Work a

Active thread, also note location in service manual of MK-1 wiring and testing 3-58 to 3-60

https://www.kawasakiversys.com/foru...-650/217113-v-died-while-riding-wont-start-again-vehicle-down-sensor-fault.html

 

[onewizard]

Single Series resistor / Voltage Drop

I am pleased to announce that I was both right and wrong about the vehicle down sensor (VDS for short).

a) disconnecting the VDS is not a workaround. The checking time from the ecu is longer than 5 seconds. I suspect it is on some internal clock so it can be quick or slow. Feels more like 8 seconds.

b) the resistive hack WORKS! I rode 5 minutes. No issue, no odd lights. ECU completely fooled. And if I disconnect it wile running, bike turns off within the usual 8sec.

This is before putting duct tape to hold in place. Something more tightly fitting would be recommended, as it is rather unreliable like this, and not waterproof.

What I found is the ECU current from the output of the VDS is 36.45 micro amp as measured using a Fluke 189, on my 2015. Input voltage is 5.01 VDC as measured using a Fluke 189.

Voltage at the output of the VDS 3.98 to 3.99 VDC at idle running, with battery @ 14.2 to 14.3 VDC . I used a 32.6 K ohm resistor in series with the Blue and Yellow Green which gave a VDC 3.89 VDC ( voltage drop of 1.11 VDC) . I also used a 38.9 K ohm which produced a 3.73 VDC output ( voltage drop of 1.27 VDC). Both cases the bike ran for 5 minutes, when the wire fell out, it shut down around 7 seconds.

So both resistors are readily available. I have created a voltage drop equal to what the sensor input is,by measuring the current and by what I calculated ( original called for a 30,660 ohm resistor. The ones I used I had plenty in stock.

So if I would be a person heading out on a long trip with a MK-1 and you had similar trouble but it went away ( yes I would buy a new sensor however) as a backup you could first try either the 32.6K or the 38.3 K resistor, fold the ends over to double the thickness and insert between the Blue and Yellow
/ Green , measure VDC to ground from the yellow / green side of the resistor,if you are in the ball park of the values in the manual or those I displayed, pack a roll of electrical tape and I would suggest taping the resistor to the wiring harness of the VDS , give the tape a double rotation before ripping off, this is your start to remove the tape (the 2015 there is a frame ground less than 5 inches from the sensor)

36.55 micro amp DC Notice to the left of the 36.55 there is no triangle like the last photo, that is because one lead fell out and I keyed off, and noticed a error of 0.09 micro amps possibly induced, so the last photo I used REL to zero the display. ( ya I know, all gobbledygook :nerd: just remember, eventually some of this may sink in > well if you read it enough) :huh: Also note the photos from dddd are much clearer and easier to understand. And that is the difference between a Master Electrician with Electronics and a Engineer >

I am measuring between the left Blue 5.01 VDC supply in series with my Fluke meter on micro amps DC and the center input Yellow /Green

Using REL as there was a error of .09 micro amps with the leads disconnected, probably induced, but you will see a triangle to the left which indicates REL ( very similar to zeroing the resistance of the leads when measuring resistance)

Output of VDS @3.98 VDC

Using a single 32.6 K resistor between the Blue and Yellow 3.89 VDC

Using a 38.9 K resistor @ 3.72 VDC

Actual micro amps after using relative, really didn't need to but the meter read 0.09 micro amps high with open leads.

 

[onewizard]

FYI how I arrived at the resistance is using ohms law, I measured 0.00003645 amps , so I wanted a 1 volt drop, from the supply voltage of 1 volt, resistance is found by dividing voltage by current so that gives us 27434 ohms, that was a ball park, it turned out that 32K was better.

FYI another member tried this and it didn't work for him, however dddd method did work.

 

[onewizard]

Service manual testing

Hard to find but in DFI chapter

Please note the mention in the second last *, about the ECU ground, this is under the seat / gas tank support bracket on the foot brake side of the bike, you cannot see it unless the bracket is removed, trust me I was surprised after owning a 07 and now the 2015 It is not backed up with a copper connection to the negative ground wiring system , it depends solely on the steel frame