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| @rt |
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Hi Guys,
I'm working on another small microcontroller project. It is a digital speedo that I would like to eventualy mount inside my EL instrument cluster. A prototype can be seen in my gallery, however, the final will use Blue LED displays. I found the speedo signal on my BEM to be the white lead. The signal is by no means pulse width modulated as stated in the table on the BEM connector: http://www.fordmods.com/forums/documents.php?doc=49 The pulse width does not change, but the frequency of the pulses does get faster with speed. I have yet to determine if this happens on a linear scale, but my proto unit can already count pulses. Fortunately, I will find this type of signal much easier to program for. It's a good thing the digital speedo mode on the cluster can be used to calibrate it. Any comments/suggestions welcome, especialy from others who have played with microcontrollers/ECU/BEM. Cheers, Art.
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| 1 SLY 97EL |
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Sounds Cool. But didn't the Old XF's have it and Ford ditched cause them they started having inaccuracy and other assorted Electrical gremlins with the Dashs
_________________ " In life their is never an Obligation just an Opportunity to..Own an awesome 1970 Ford Mach 1 Mustang! " |
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| fuzion |
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im quite sure you will need some engineering certificate for it not being standard.
are analogue dials hard to read? plus u can go in diagnostics mode and have the speedo displayed in digital. good idea and all i give u that but eh ! |
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| @rt |
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Quote: im quite sure you will need some engineering certificate for it not being standard.
This could be a problem.. I wasn't aware that a speedo was even required to make a car roadworthy. I will have to look into that. As for the reliability issue, some older fords did have complete digital clusters, but I'm pretty sure that any issues were related to the specific models used. Digital speedos are still used today in some new cars ie. Toyota Echo. BTW, I can't view pictures other than avatars on this site, so any images of ECU, diagnostic, or BEM modules would be appreciated art@austech.info I am aware of the digital speedo in the cluster diagnostic mode.. I had considered trying to read the speed from the data line between the cluster and trip computer, but since the communication protocol is unknown to me, I'd rather not waste time on something that i 'might' figure out. Yes, I think a big blue digital display would be more appealing and easier to read than a dial guage. Cheers, Art.
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| mspw |
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Fellows, we are not seeing the bigger picture.
This could be a beautiful mod as a reflector display directly onto the windscreen for night cruising. My girls Nissan Bluebird has this feature - its the best part of the car. Reflects off a small square of reflective metalized tint onto the right drivers windscreen corner.
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| dddp! |
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@rt wrote: Quote: im quite sure you will need some engineering certificate for it not being standard. This could be a problem.. I wasn't aware that a speedo was even required to make a car roadworthy. I will have to look into that. As for the reliability issue, some older fords did have complete digital clusters, but I'm pretty sure that any issues were related to the specific models used. Digital speedos are still used today in some new cars ie. Toyota Echo. BTW, I can't view pictures other than avatars on this site, so any images of ECU, diagnostic, or BEM modules would be appreciated art@austech.info I am aware of the digital speedo in the cluster diagnostic mode.. I had considered trying to read the speed from the data line between the cluster and trip computer, but since the communication protocol is unknown to me, I'd rather not waste time on something that i 'might' figure out. Yes, I think a big blue digital display would be more appealing and easier to read than a dial guage. Cheers, Art. i used to have a ford telstar ghia, actually a mazda 626 sdx, it had a digital speedo, i liked it, found it easy to read and it was clear all the time i think ford dtopped using them because people reckoned they were hard to read, journos mostly critising the digital displays,tho personally i never had any problems with it |
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| twr7cx |
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mspw wrote: Fellows, we are not seeing the bigger picture.
This could be a beautiful mod as a reflector display directly onto the windscreen for night cruising. My girls Nissan Bluebird has this feature - its the best part of the car. Reflects off a small square of reflective metalized tint onto the right drivers windscreen corner. Seen a Silvia with this, I liked. I would of thought so long as you still had your original speedo you wouldn't need to worry about the certificate. |
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| @rt |
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I don't think there is any question about having it as an addon,
but my intention was to replace the dial guage inside the cluster, and bin the old guage 
Problem might be solvered anyhow.. there happens to be a cluster on eBay at the moment with faulty speedo.. that being the case, it shouldn't fetch too much, so if I can keep my original cluster intact, the modded one could always be replaced when it came to selling the car. If all goes as it should, I will post a shematic, and software for the microcontroller for those who like to solder. Art.
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| Happy |
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@rt wrote: I don't think there is any question about having it as an addon,
but my intention was to replace the dial guage inside the cluster, and bin the old guage Problem might be solvered anyhow.. there happens to be a cluster on eBay at the moment with faulty speedo.. that being the case, it shouldn't fetch too much, so if I can keep my original cluster intact, the modded one could always be replaced when it came to selling the car. If all goes as it should, I will post a shematic, and software for the microcontroller for those who like to solder. Art. just a small question, are you going to have a 199 display or a 999 display?  for obvious reasons hehe!
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| twr7cx |
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@rt wrote: I don't think there is any question about having it as an addon,
but my intention was to replace the dial guage inside the cluster, and bin the old guage I wouldn't worry to much, most cops don't seem to give a toss about too much if your polite to them. But you might have insurance hassles if you ever make a claim and they check out your car. I'd do it if I was you thouhg! |
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| data_mine |
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1 SLY 97EL wrote: Sounds Cool. But didn't the Old XF's have it and Ford ditched cause them they started having inaccuracy and other assorted Electrical gremlins with the Dashs
The speedo's (indeed everything) on the EF+ (possibly earlier models too, I'm unsure) clusters are all digital anyway.
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| twr7cx |
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data_mine wrote: 1 SLY 97EL wrote: Sounds Cool. But didn't the Old XF's have it and Ford ditched cause them they started having inaccuracy and other assorted Electrical gremlins with the Dashs The speedo's (indeed everything) on the EF+ (possibly earlier models too, I'm unsure) clusters are all digital anyway. Analoge presentation, but it's a motor that turns the needle from the signals it gets. It's electical not mechanical. |
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| ItchiOne |
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wrote: The pulse width does not change, but the frequency of the
pulses does get faster with speed. I have yet to determine if this happens on a linear scale, but my proto unit can already count pulses. Fortunately, I will find this type of signal much easier to program for. This sounds interesting.. In my EF, a speed signal is sent from the speed sensor to the cluster which then 'masages' the signal and sends it to the ECU and cruise control. I think it may also go to the BEM for the speed sensitive intermittant wiper function. All wires are white 
I vaugly remember reading that the speed sensor signal (cluster speed input - right plug pin 3) is frequency modulated and the massaged signal is pulse width modulated (cluster speed out - right plug pin 4) but not sure 
Which wire are you using and can you/ do you intend to convert the speed sensor output to that used by the ECU, CRUISE and BEM ? Cheers. |
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| @rt |
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Quote: just a small question, are you going to have a 199 display or a 999 display? for obvious reasons hehe!
Well I wouldn't want it to be limited to 199 since the original speedo reaches at least 220 from memory. I don't know where to buy a '1' digit anyway. I won't ever go over 200, but someone else might make it that does. I am taking the signal from the BEM. Apparently this output does not exist on Gli models, and so would have to come from somewhere else. An interesting observation that I made with my prototype, is that even when I'm moving at very slow speed (ie. pulling out of the driveway), there are still very slow pulses transmitted way before the analogue speedometer even moves. I call it analogue, although there appears to be some debate here, the signal is digital until it reaches the cluster, and thereafter, the dial guage suffers all of the cons of an analogue guage, and would be prone to the same causes of mechanical failure. Anyway.. my point being.. All I need to do is crawl along slowly at night on a quiet road, and use my proto to count pulses until the odometer jumps 0.1 Kms, and then I have precise info to do the speed calculation. Art.
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| @rt |
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Ok, Here's some information that you won't find in the manual
It's 4:15am, and I'm back from my test drive along the highway. I took my proto which was hooked up, and I used a simple counting program and the car's odometer to count how many pulses it would take for the odometer to move by 0.1 Km. The result is 625 pulses = 0.1 Km. As a further test, I reset the trip meter, and reset my counter, then drove VERY slowly for another 0.1 Km, and my counter read exactly 625 pulses for the second time. Then I drove at erratic speeds, slowing down so I could bring the car to a stop when the counter read 250 (for actual 1250 pulses). On the 1250th pulse, the trip meter jumped to 0.2 Km. It doesn't take a genius to figure out that the odometer is working directly from this signal, and the number of pulses per Km is 6250. Art.
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