Cruise Control?

Discussion in '6.9L IH & 7.3L IDI Diesels' started by lkrasner, Nov 4, 2018.

  1. lkrasner

    lkrasner Registered User

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    My 94 E350 short bus does not have cruise control. I plan on using it for long road trips, and it would certainly be a nice feature to have. Experience tells me driving a truck across Iowa without it blows. Is it possible to add?
     
  2. franklin2

    franklin2 Full Access Member

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    Aftermarket kit would be the easiest, but they are not cheap like they used to be. Not much market for them anymore. If you try to put a factory setup on it, you have different wiring for the horn and the steering wheel to mess with.

    Here is a aftermarket kit on ebay.

    https://www.ebay.com/itm/253612150769
     
  3. raydav

    raydav Full Access Member

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    I added factory cruise to my IDI in the early nineties. For the 2014 Pony Drive I installed the system noted above in my 65 Mustang. A few months ago I put the same system in my IDI. It is better than stock.
     
  4. lkrasner

    lkrasner Registered User

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    Alright, I will definitely look into the aftermarket units. Also considering building one myself. as I see it, it's a simple system. I'd love any feedback from anyone whose worked in cruise control electronics. The only output will be something to pull a throttle cable. The only input should be from the VSS, and probably the brake switch for auto deactivation. From there it's just software to actuate the throttle based on current speed. Sounds like a great job for a little microcontroller that could also act as the tachometer this truck is missing...
     
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  5. ifrythings

    ifrythings Full Access Member

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    I would just grab the factory electric cruise off of a 92-94 pickup and install it into your van, it’s 7 wires and very easy to install and way better then the vacuum cruise on the earlier trucks.

    Making a cc unit is no simple task, you need to program it right so it doesn’t act like an on off switch on the throttle but is also not slow at responding, your looking into PID control for that.

    And a tach from road speed would be very inaccurate, better off using a factory tach sensor and making a gauge from that.
     
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  6. lkrasner

    lkrasner Registered User

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    I know it's not that simple, and I am rather familiar with PID, and really want to learn more about it. I'm an electrical engineering student, so this is exactly the kind of stuff I do. having personal projects I can swing as class projects is a great way to get free (well, with thousands in tuition...) parts and advice. I think it would be an interesting project; I'm going for learning, not necessarily the best / cheapest solution.

    I was absolutely planning on using the factory tach sensor for that aspect. I need to find the specs of the output or get a scope on it, but that should be a very easy project.
     
  7. ifrythings

    ifrythings Full Access Member

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    I’m definitely no EE, just your standard tinkerer, I do know a bit about the cruise control that ford uses (not so much on the programming).

    Minuumin speed input is 30mph before turning on, max speed was up around 212mph (why!?! Ford???) before it kicked out. They use a stepper motor driving a electromagnetic clutch, spring loaded drum for the speedo cable, the clutch is engaged and stays engaged during cruise control and disangeges when either the speed is below 30mph, brake is pressed, brake pressure sensor measures over 8-10psi, speed is 20mph above or below the set point or you hit the off button. They don’t use the stepper to return the throttle cable, the spring in the drum does that for a quick release of the throttle. Speed input is the standard 8000 pulse/ per mile.

    That’s what I found out playing around with a unit on the bench, hope that helps you for your project.
     
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  8. lkrasner

    lkrasner Registered User

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    Thanks. I'm sure it will prove useful. It will be interesting to see how it turns out. Nice part about building my own system is I can tweak it to do whatever I want, and make it work well for my vehicle.
     
  9. raydav

    raydav Full Access Member

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    I had the Rostra unit on my 65 Mustang for several years before I put one on my van. The advantages over the stock vacuum system are the resume function and an LED to indicate engaged. I put the set/coast and accelerate/resume on a SPDT momentary mini toggle switch on the console.

    When I put the same model Rostra on my van it worked OK sometimes and other times the engaged LED would go on and immediately go off. So, after a couple days of that, I put the back axle on stands, put a scope on the VSS and a white LED on the brake switch. I fiddled with that for part of two days and found nothing. Those two days the weather was clear and chilly so I had the van out in the sun.

    The next day was warm so I put the van under cover where it was much darker. And that was where I saw a faint flicker on the brake pedal switch. I looked at the brake input to the Rostra controller and found it at about 9 Volts; which I figured was probably close to the trip point.

    My convertible has high voltage ignition near by and has no noise issues. The van has no noise source that I can identify but has a noise problem. So I put a relay between the brake switch and the Rostra input. The relay is unable to respond to the noise so there is an absolute one or zero now on the Rostra input. All is well.

    So make yourself a system. If you have nothing else to do it will probably take you six months to get a system anywhere close to a commercial unit and cost more than the Rostra's $200. I have been there a few times; my van instrument area is currently a driveable breadboard, including a couple clip leads.

    But have fun.
     

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