Harley Davidson V-Rod Forum banner

1 - 20 of 22 Posts

·
Registered
Joined
·
1,037 Posts
Discussion Starter #1
I have an 09 with the acoustical sending unit and well in the last two days my gauge has started acting up, surprise surprise 10,000 miles before it did though...

Using the Hail Mary search function I have been able to ascertain that the sending unit itself seems to have the look up tables in it to convert the sonar reading to a usable signal for the instrument cluster. What I want to know is what is the usable signal it puts out, also does it put out a digital signal to the ECM? Is a 4-20mA, 0-5v, 5-9.5v or what? If it is analogue voltage out is it linear on non-linear? Last but not least does anyone know who their manufacturer is for there sending unit?
 

·
# 12/50 Ignite LE
Joined
·
2,911 Posts
I have not seen that info on the forum but hopefully someone knows for sure. But I do recall that someone speculated it was a voltage output. But if all they did was put a volt meter on the "output" of the sending unit and measured a voltage and deduced that it was a voltage, it could be an incorrect statement. Voltage is present even on the output of the typical resistive sending unit when it is powered up, but most know that this type of sending unit is passive and does not produce a voltage.

It would be nice for the people with the new style sending unit if it still ends up resistive in nature. Then a resistive element of proper value could then be installed in its place. Turning the key in a certain direction and clicking your heals once a month is NOT a fix, nor is running a cup of morning urine through the system as some suggest. That design is/was a turd on the drawing board.
 

·
Super Moderator
Joined
·
6,248 Posts
I have an 09 with the acoustical sending unit ...
What I want to know is what is the usable signal it puts out, also does it put out a digital signal to the ECM? Is a 4-20mA, 0-5v, 5-9.5v or what? ....
The sonic fuel level sensor outputs an analog voltage signal that varies from 0.9V to 3.8V (full to empty).

This is based on information from 2010 EDM (99499-10) page 4-3:

The ACC FUSE provides battery voltage (O/W) wire to the fuel level sensor which determines distance to fuel, then outputs a voltage signal typically between 0.9V (full) and 3.8V (empty) to the IM on the (Y/W) wire. The IM monitors this signal to calculate fuel level and distance verses volume.
 

·
Registered
Joined
·
1,037 Posts
Discussion Starter #4
The sonic fuel level sensor outputs an analog voltage signal that varies from 0.9V to 3.8V (full to empty).

This is based on information from 2010 EDM (99499-10) page 4-3:

The ACC FUSE provides battery voltage (O/W) wire to the fuel level sensor which determines distance to fuel, then outputs a voltage signal typically between 0.9V (full) and 3.8V (empty) to the IM on the (Y/W) wire. The IM monitors this signal to calculate fuel level and distance verses volume.
Thank you that is what I was looking for. Does it say anything about a signal to the ECU?
 

·
Super Moderator
Joined
·
6,248 Posts
Thank you that is what I was looking for. Does it say anything about a signal to the ECU?
The communication between the ECM and IM is via the serial data bus ((LGN/V) wire but fuel level is not digitized and sent out on the bus.

BTW, the ECU on a VRSC bike is part of the ABS system so it’s confusing to use this in place of ECM.
 

·
K.I.A. '07 AW
Joined
·
10,908 Posts
shaggyhou, you need to get in touch with forum member beastwood.. Check out his thread here
 

·
Registered
Joined
·
1,037 Posts
Discussion Starter #7
Yeah I have looked at his P-Dash and it look like he reading everything through the on-board diagnostic port. What I am attempting to do is basically see about sending a feed direct from a reliable sending unit to the gauge and possibly the ecu as well pending the information I can find out about communication protocol to the ECM. Since I work in oilfield controls I have several contacts at my disposal to see about getting a reliable sender if I can get all the info I need to do this. So far it looks like though that it will be easier to add a second analogue sender and feed the gauge itself to make it accurate and let the ECM get inaccurate information from the stock sending unit, not what I would want but possibly doable from what I am finding out.
 

·
K.I.A. '07 AW
Joined
·
10,908 Posts
I understand, but believe beastwood was working on fuel level data as well.
 

·
# 12/50 Ignite LE
Joined
·
2,911 Posts
As I mentioned before, the HD ECM doesn't use fuel level data, accurate or otherwise. The fuel level sender output is used only by the IM fuel level gauge.
You have any info on where signal conditioning takes place? In the sonic fuel level sender or in the IM?.
 

·
Super Moderator
Joined
·
6,248 Posts
You have any info on where signal conditioning takes place? In the sonic fuel level sender or in the IM?.
Only what I quoted above from the 2010 EDM. This implies that it’s the sending unit in the fuel tank that does the signal conditioning.
 

·
Registered
Joined
·
178 Posts
I understand, but believe beastwood was working on fuel level data as well.
I got a pm and email from Shaggyhou requesting info about fuel consumption measuments in PDash. Here's everything I know...

I don't use any information that comes from the sending unit. I've actually looked at that data on the bus and it is horribly inaccurate (at least for my bike - 07DX) However, after a bit of reverse engineering I found another (undocumented) fuel message which provides fuel use at an incredibly high resolution (~1/4000 of a gal). I suspect that it's actually counting fuel injector pulses. (Although this is purely speculation on my part) Using this data I've been able to regularly run my bike down to vapors without fear running out of gas.
If anyone has more detailed information or a better guess at what the data I'm reading is really measuring I'd be interested. The biggest problem with reverse engineering is that while you can determine that certain data correlates with specific functions, and you can use those correlations to make predictions, you don't always know how the data was generated. And while that info isn't necessary it's always better knowing so that you can have a full understanding of how the ecm is processing the various sensor data.

-Bob
 

·
durata membro
Joined
·
17,603 Posts
I have not seen that info on the forum but hopefully someone knows for sure. But I do recall that someone speculated it was a voltage output. But if all they did was put a volt meter on the "output" of the sending unit and measured a voltage and deduced that it was a voltage, it could be an incorrect statement. Voltage is present even on the output of the typical resistive sending unit when it is powered up, but most know that this type of sending unit is passive and does not produce a voltage.

It would be nice for the people with the new style sending unit if it still ends up resistive in nature. Then a resistive element of proper value could then be installed in its place. Turning the key in a certain direction and clicking your heals once a month is NOT a fix, nor is running a cup of morning urine through the system as some suggest. That design is/was a turd on the drawing board.
That's all I do.I turn the ign switch to ACC about once a month.This makes my 07 VRSCX with an 09 F sender less the 09 download fuel gauge and all of it's functions work flawless since Oct of 08.
Mine is not the only one that works flawless by doing this little self check.
It doesn't matter to me if this is how it should work,it matters that it does work by doing the self test.

My 06 mustang has a quirky procedure to read correctly after every fillup.Again,after many trips to the dealer and having oil soaked dipshits working on the car,I don't mind the little recal procedure because this system works for me too.
 

·
Registered
Joined
·
1,037 Posts
Discussion Starter #14
That's all I do.I turn the ign switch to ACC about once a month.This makes my 07 VRSCX with an 09 F sender less the 09 download fuel gauge and all of it's functions work flawless since Oct of 08.
Mine is not the only one that works flawless by doing this little self check.
It doesn't matter to me if this is how it should work,it matters that it does work by doing the self test.

My 06 mustang has a quirky procedure to read correctly after every fillup.Again,after many trips to the dealer and having oil soaked dipshits working on the car,I don't mind the little recal procedure because this system works for me too.
Unfortunately for me I have been and continue to do so the self check by turning the key to accessory, I do it after every fill up though which is every two days normally but since it has started acting up I have been running it every time I start the bike.


As I mentioned before, the HD ECM doesn't use fuel level data, accurate or otherwise. The fuel level sender output is used only by the IM fuel level gauge.
That is interesting, if the ECM is not using the data then why is there communication between the two and also an error code for fuel to low? The reason I wanted to maintain communication between the ECM and sending unit was to not throw check engine lights. I doubt the ECM needs the data to run the the bike but if communication gets severed will it throw a code and light up the dash?
 

·
Registered
Joined
·
1,037 Posts
Discussion Starter #15
I got a pm and email from Shaggyhou requesting info about fuel consumption measuments in PDash. Here's everything I know...

I don't use any information that comes from the sending unit. I've actually looked at that data on the bus and it is horribly inaccurate (at least for my bike - 07DX) However, after a bit of reverse engineering I found another (undocumented) fuel message which provides fuel use at an incredibly high resolution (~1/4000 of a gal). I suspect that it's actually counting fuel injector pulses. (Although this is purely speculation on my part) Using this data I've been able to regularly run my bike down to vapors without fear running out of gas.
If anyone has more detailed information or a better guess at what the data I'm reading is really measuring I'd be interested. The biggest problem with reverse engineering is that while you can determine that certain data correlates with specific functions, and you can use those correlations to make predictions, you don't always know how the data was generated. And while that info isn't necessary it's always better knowing so that you can have a full understanding of how the ecm is processing the various sensor data.

-Bob
Thanks Beastwood. I wounder if there is a possibility that we have a fuel flow meter somewhere in the system or maybe you are possibly even reading the digital signal directly from the sending unit itself, not the signal as stated by the ECM. As it has been stated before sonar based fuel level systems can be very accurate leading some to believe that it may be within Harley's handling of the data or possibly within the sensor itself when it gets its data and converts it to the analogue out for the dash. I would suspect it might be both as the analogue system feeds straight to the gauge according to Stever and that the handling of the data by Harley is not on par with the sensor, assuming that when you say you are reading the "published" signal for the sending unit. In other words the "published" signal is basically has been reconditioned by the Harley ECM and the higher resolution maybe the signal straight from the sensor?

Beastwood, you are getting all your readings from the OB diagnostics port correct?
 

·
Registered
Joined
·
178 Posts
Thanks Beastwood. I wounder if there is a possibility that we have a fuel flow meter somewhere in the system or maybe you are possibly even reading the digital signal directly from the sending unit itself, not the signal as stated by the ECM. As it has been stated before sonar based fuel level systems can be very accurate leading some to believe that it may be within Harley's handling of the data or possibly within the sensor itself when it gets its data and converts it to the analogue out for the dash. I would suspect it might be both as the analogue system feeds straight to the gauge according to Stever and that the handling of the data by Harley is not on par with the sensor, assuming that when you say you are reading the "published" signal for the sending unit. In other words the "published" signal is basically has been reconditioned by the Harley ECM and the higher resolution maybe the signal straight from the sensor?

Beastwood, you are getting all your readings from the OB diagnostics port correct?
Yes, PDash only uses bike data that is found on the OBD bus via the data link connector. Obviously I fuse data received from the OBDPro (battery voltage) as well as Accelerometer, Temperature, GPS (lat, long, heading, altitude, velocity), etc. from the handheld to generate the PDash display. But there are no other "wired" inputs.

I have found two messages on the bus with regard to fuel use. One is the "documented" Fuel Used (In Percent) This is the value that is totally unreliable and is not used by PDash. The second message (the undocumented one) is the one I described above.
While it is possible that these messages represent data coming from the sending unit, I'm dubious. I am more inclined to believe that the data comes from some other source (e.g. fuel injectors. ???). This would be easy to test by simply disabling the sending unit (and/or it's signal) and running PDash to see if there are still valid fuel use messages.
If there is an easy way to disable the sending unit? (i.e. a fuse) I will certainly give it a go for you.

As for the cluster (IM) and the other components (ECM, TSSM), stever975 clearly knows much more than I about their operation. So when he says that the ECM doesn't use the data from the Fuel Sending unit I would take his word for it. However I do know that the ecm does send a low fuel indicator (tell-tale) message to the cluster when the low fuel condition is detected. Which I assume the cluster uses to trigger the low-fuel warning light. However, the cluster could also be getting the low-fuel information from the sending unit or even from itself when the fuel gauge drops below a particular level. There is no way of knowing from where I'm sitting on the bus.

-Bob
 

·
Registered
Joined
·
1,037 Posts
Discussion Starter #17
Yes, PDash only uses bike data that is found on the OBD bus via the data link connector. Obviously I fuse data received from the OBDPro (battery voltage) as well as Accelerometer, Temperature, GPS (lat, long, heading, altitude, velocity), etc. from the handheld to generate the PDash display. But there are no other "wired" inputs.

I have found two messages on the bus with regard to fuel use. One is the "documented" Fuel Used (In Percent) This is the value that is totally unreliable and is not used by PDash. The second message (the undocumented one) is the one I described above.
While it is possible that these messages represent data coming from the sending unit, I'm dubious. I am more inclined to believe that the data comes from some other source (e.g. fuel injectors. ???). This would be easy to test by simply disabling the sending unit (and/or it's signal) and running PDash to see if there are still valid fuel use messages.
If there is an easy way to disable the sending unit? (i.e. a fuse) I will certainly give it a go for you.

As for the cluster (IM) and the other components (ECM, TSSM), stever975 clearly knows much more than I about their operation. So when he says that the ECM doesn't use the data from the Fuel Sending unit I would take his word for it. However I do know that the ecm does send a low fuel indicator (tell-tale) message to the cluster when the low fuel condition is detected. Which I assume the cluster uses to trigger the low-fuel warning light. However, the cluster could also be getting the low-fuel information from the sending unit or even from itself when the fuel gauge drops below a particular level. There is no way of knowing from where I'm sitting on the bus.

-Bob
I do not know if there is an easy way or not... it is looking like I need to go buy the electrical manual Stever has and trace the wires through it...

Does anyone know who makes the sending unit?? Hopefully it is one of our vendors and I can pull some strings to get more info on the internal workings of the unit itself.
 

·
matt blk & fire hot
Joined
·
1,567 Posts
As I mentioned before, the HD ECM doesn't use fuel level data, accurate or otherwise. The fuel level sender output is used only by the IM fuel level gauge.
are you sure? My understanding was the ECM looks at the fuel level at start up to determine a fuel quantity in the tank, then watches the pulse width, and number of injector pulses to calculate the miles left until the fuel is empty. it looks at start-up, and I think every 10 minutes there after for an update. the injector data is accurate, but the fuel level info can be effected by many variables. fuel slosh, fogging, vapor density, surface shape and angle, temperature, tank pressure.........

I think SSI makes the sender? but going to a capacitance type sender would be a better bet. sonic senders have limitations for depth and max fill levels that the MOCO did not adhere to.
I have found capacitance senders that have end user programmable look-up tables that you set after you install the probe. (no PC needed)
 

·
Registered
Joined
·
1,037 Posts
Discussion Starter #20
I have found capacitance senders that have end user programmable look-up tables that you set after you install the probe. (no PC needed)
Are you talking about the Centroid piece? From What I understand WEMA has a fairly accurate unit to although Centroid will build within reason whatever I spec them... Hopefully I can get a sending unit that will work from them for less then a bill.
 
1 - 20 of 22 Posts
Top