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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / March 2006OBDII
I had a need, a few days ago, to control the throttle on my pickup (2000 Ford F-150) remotely. It occurred to me that the OBDII connector might provide a path to do so. I understand that the OBDII stuff is concerned with diagnostics, but was wondering if it is anything like CAN, where any device on the net can send and receive packets. If this is so, would it be possible to send appropriate commands to any of the system components? I have extensive experience in microcontroller and PC programming, and happen to have a couple of ELM OBDII chips doing nothing. Thanks Larry Larry, I recently subscribed at www.Alldata.com to get online access to diagnostic & repair info on my '95 Park Ave. It refers to the "Tech-2" instrument, which seems to be the GM scanner used by Mr. Goodwrench. From what I've read there it can be used to send signals to the EGR valve to position it before taking readings. So, I would say it CAN be done. However, I then bought an Actron CP9145 scanner, which does not appear to allow that. IOW, I can read codes with it, but can't send info to the vehicle. Or at least I can't find anything in the manual telling me how to do it. Obviously, I'm no expert in these matters. Ed >I had a need, a few days ago, to control the throttle on my pickup > (2000 Ford F-150) remotely. It occurred to me that the OBDII [quoted text clipped - 12 lines] > Thanks > Larry A bi direction scanner such as a Snap On mt 2500 can command many functions but some are not available and it varies by car and mfg. > Larry, > [quoted text clipped - 30 lines] >> Thanks >> Larry > I had a need, a few days ago, to control the throttle on my pickup > (2000 Ford F-150) remotely. It occurred to me that the OBDII > connector might provide a path to do so. Follow the linkage from the gas pedal to wherever it ends. If it's an old-fashioned linkage, then there's no easy (built in) way to control the throttle remotely using a computer interface. If it ends in a wiring harness ("drive by wire" setup (like a 98-up Vette)), then you MAY be able to do something like what you're looking for. Ray The ray entity posted thusly: >> I had a need, a few days ago, to control the throttle on my pickup >> (2000 Ford F-150) remotely. It occurred to me that the OBDII >> connector might provide a path to do so. >Follow the linkage from the gas pedal to wherever it ends. If it's an >old-fashioned linkage, then there's no easy (built in) way to control >the throttle remotely using a computer interface. If it ends in a >wiring harness ("drive by wire" setup (like a 98-up Vette)), then you >MAY be able to do something like what you're looking for. Ahh! Didn't think to do that, but it's a good idea. I do know the throttle can be controlled electronically, because I have cruise control. Unfortunately, it might be controlled by something that moves the gad pedal (I'll have to check to see if the gas pedal moves when the cruise control kicks in). Thanks! > The ray entity posted thusly: > [quoted text clipped - 15 lines] > > Thanks! even then, you might have a mechanical throttle. But... the cruise control module might provide the "interface" you need to pull and release the throttle linkage. (you sound handy with a soldering iron...) The ray entity posted thusly: >> Ahh! Didn't think to do that, but it's a good idea. I do know the >> throttle can be controlled electronically, because I have cruise [quoted text clipped - 5 lines] >control module might provide the "interface" you need to pull and >release the throttle linkage. (you sound handy with a soldering iron...) Yup.. mechanical throttle. When the cruise control cuts in, the pedal goes down. When it cuts out, the pedal comes up. Looks like a good place to start. I sure know which end of a soldering iron to pick up! Been in the computer biz (fixing and programming) for pretty close to 40 years. > The ray entity posted thusly: > [quoted text clipped - 13 lines] > Been in the computer biz (fixing and programming) for pretty close to > 40 years. You don't mention why you need to control the engine speed but why not use the IAC motor circuit ? Thats's what the computer uses to control engine speed. The Mike entity posted thusly: >> The ray entity posted thusly: >> Yup.. mechanical throttle. When the cruise control cuts in, the pedal >> goes down. When it cuts out, the pedal comes up. Looks like a good [quoted text clipped - 5 lines] >the IAC motor circuit ? Thats's what the computer uses to control engine >speed. I'm not at all familiar with the 'IAC motor circuit'. I was hoping that the OBDII was basically a hub in a network that had various sensors and actuators on it, and that I could just use the OBDII connector, a micro or two, and perhaps my laptop to control things like throttle. I'd like to hear more about the 'IAC motor circuit'. The reason I need to control motor speed is that I occasionally need to use it to pull my tractor backwards when I am moving round hay bales in the winter. The bales on the front-end-loader cause a loss of traction on the rear wheels of the tractor. Often, there is nobody around to help out by driving the truck, so I figure I can do it single-handedly with a radio-controlled throttle. Heck, maybe I should set my sights higher and see if I can radio-control the whole truck. It would come in real handy at harvest time. Are you sorry you asked? :-) Larry > The Mike entity posted thusly: > [quoted text clipped - 16 lines] > connector, a micro or two, and perhaps my laptop to control things > like throttle. ODB II stands for onboard diagnostics II. It was an attempt to standardize wiring and connectors so that a "universal" scan tool could be used on all cars. It didn't work out all that well. The ECU ( engine computer ) has the job of air/fuel managenent and also controls ignition timing. All sensors are hard wired directly to the ECU. No network involved. > I'd like to hear more about the 'IAC motor circuit'. Most IAC motors ( idle air control ) are pulsed stepper motors operated by the ECU. They control idle speed by opening or closing an air passage which is behind the throttle plate. More air = faster idle, less air = lower idle > The reason I need to control motor speed is that I occasionally need > to use it to pull my tractor backwards when I am moving round hay > bales in the winter. The bales on the front-end-loader cause a loss of > traction on the rear wheels of the tractor. Often, there is nobody > around to help out by driving the truck, so I figure I can do it > single-handedly with a radio-controlled throttle. You would need to find some wiring diagrams to start. The manufacturers don't want anyone to know exactly how the computer (ECU ) is programmed so this info will not be available. But with a wiring diagram you should be able to figure out how to manipulate the IAC motor. It's basicly power on one wire, ground on another = motor travel out, switch polarity = motor travels in. The IAC motor should be located on the throttle body. There was a product made to do just this on a jeep. It was not radio controled. It was wired in and the control was mounted by the shifter. When you got in a tricky spot off road with a manual trans jeep you could electronicaly raise the idle speed so you could use one foot on the brake and one on the clutch.Don't know if it's still in production but it would most likely to be able to be adapted to your vehicle. > Heck, maybe I should set my sights higher and see if I can > radio-control the whole truck. It would come in real handy at harvest > time. LOL. If you can pull that one off I gaurentee you will be able to sell it. :) > Are you sorry you asked? :-) Not at all. If you do decide to take on this project let us know how it turns out. > Larry The Mike entity posted thusly: > ODB II stands for onboard diagnostics II. It was an attempt to >standardize wiring and connectors so that a "universal" scan tool could be >used on all cars. It didn't work out all that well. OK, I was afraid that's all it was, but figured it was worth finding out more. > The ECU ( engine computer ) has the job of air/fuel managenent and also >controls ignition timing. All sensors are hard wired directly to the ECU. No >network involved. Ahh... I see. >> I'd like to hear more about the 'IAC motor circuit'. > > Most IAC motors ( idle air control ) are pulsed stepper motors operated >by the ECU. They control idle speed by opening or closing an air passage >which is behind the throttle plate. More air = faster idle, less air = lower >idle Would that give a pretty good range of idle? I figure I'd probably need about 2000-3500 RPM, depending on conditions (ground it's sitting on, how slippery, etc.). >> The reason I need to control motor speed is that I occasionally need >> to use it to pull my tractor backwards when I am moving round hay [quoted text clipped - 9 lines] >one wire, ground on another = motor travel out, switch polarity = motor >travels in. The IAC motor should be located on the throttle body. I'll see what I can find. Would that info be available to the consumer from Ford? >> Heck, maybe I should set my sights higher and see if I can >> radio-control the whole truck. It would come in real handy at harvest >> time. > > LOL. If you can pull that one off I gaurentee you will be able to sell >it. :) Heh! Well, it's certainly possible, if by no other method than using mechanical actuators to handle the controls. I'm not sure I'd like to attempt it, but it's real fun to think about. >> Are you sorry you asked? :-) > > Not at all. If you do decide to take on this project let us know how it >turns out. I will. Thanks for the info! Larry > The Mike entity posted thusly: > [quoted text clipped - 60 lines] > > Larry I think you metioned that you had cruise control. If so this may work Scroll down to the bottom of the page to the Throttle/Winch Control. http://www.kwanms.com/ The Mike entity posted thusly: > I think you metioned that you had cruise control. If so this may work >Scroll down to the bottom of the page to the Throttle/Winch Control. > > http://www.kwanms.com/ Interesting link! The idea of controlling the winch from inside the car is a good one indeed. |
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