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Cruise Control Upgrade

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    Cruise Control Upgrade

    I am trying to add Cruise Control to my 1993 318i Touring and am having some difficulties. I still can't get it to work. Here's what I've tried:

    Installed all the components (i.e. harness, actuator, electronic box, clutch switch, brake switch, column switch) into the vehicle

    Verified that the harness is good and all pinouts are correct
    Verified that the actuator motor and relay are good.
    Verified that that the clutch and brake connections are correct.
    Verified that 12v is available in the system.

    It still doesn't work. I have no way to test the electronic box, so I have ordered a new one. Does anyone else have an idea what to try next, if this doesn't work?

    Is it getting VSS from the cluster?
    Originally posted by priapism
    My girl don't know shit, but she bakes a mean cupcake.
    Originally posted by shameson
    Usually it's best not to know how much money you have into your e30


      The wire is hooked up. I haven't checked for a signal.

      How do I check for a signal? What does it look like?


        I have discovered that I do have a VSS signal from the cluster.

        Some research that I have done says that the signal is a square wave. Without hooking up an oscilloscope, I can't confirm that.

        I can confirm that there is .5 volts of VSS signal and that it changes with higher and lower speeds.

        I'm getting ready to take apart the actuator. I can hear solenoids and motors running, but no movement of the cable.


          The Cruise Control is FIXED!

          During one of my trouble shooting events, one of the little gears in the actuator was reinstalled not exactly where it belongs.

          All is well now.


            For anyone who wants to add a Cruise Control to their E30, here's a few things I learned:

            If you have a choice, get all the parts from the same car. That way you don't have to worry about compatibility. There appears to be an older and a newer system. They are not compatible. Make sure all of your parts are of the same configuration. Here are the parts you'll need:

            1.) Steering column switch (airbag cars have a different switch than non-airbag cars)
            2.) Harness
            3.) Actuator (and bracket)
            4.) Electronic Box (and bracket)
            5.) Clutch switch (and bracket)
            6.) Green plug for instrument cluster

            Here are a few details about the installation:

            1.) If your car never came with a Cruise Control ( i.e. 318is, M40 engine models, etc.) you will have to adapt the Actuator bracket to mount to the same bracket that holds the air filter housing. Mine just took a small strap to connect to the air filter housing bracket.
            2.) You might have to shorten the rod that connects the actuator bracket to the throttle connection. I shortened mine and used a die to add more threads to the rod at the throttle. The engine throttle should have a space for another connection. That's where you connect your cruise cable to the throttle.
            3.) You'll have to thread the wire connected to the actuator through the firewall. Its easier to run a piece of spare wire from the cabin to the engine compartment and tie that to the actuator connector. Pull that spare wire/connector assembly into the cabin.
            4.) The standard location of the Electronic Box is above the Engine Computer above the glove compartment. It doesn't look like it will fit there, but it does. If you don't want to put it there, you probably can find a place on the drivers side. If you decide to put it in the standard glove box location, it will be easier to route the harness by removing the cluster and using that access hole to route the harness behind the radio.
            5.) Most of the harness connection is easy: you just plug all the mating connectors together. The exceptions are probably going to be at the clutch and brake switches. You will probably have to splice some wires at these locations.
            6.) The clutch switch has two wires going to it. The locations are interchangeable.
            7.) The brake switch has two wires going to it. They are not interchangeable. You must connect the Power wire (violet/white on my car) of the Cruise harness to the wire going to the brake pedal that has power when the key is on and the brake pedal is not pressed. Both wires on the brake switch have power when the pedal is pressed. But you need to connect the violet /white wire to the one that has power all the time that the key is on. This is where the Cruise Control system gets its power.
            8.) The lower plastic panel on the steering column needs a cutout on it so that there is room for the stalk switch. You can buy a trim piece with a hole, or just cut your own from the trim piece you have. The plastic cuts easily and the cutout location is marked on the inside of the panel.
            9.) The VSS wire that plugs into the cluster can go into any of the three places that it fits. They are all electrically connected so it doesn't matter which one you use.
            10.) You can use the early part number electronic module with the later switch, module and harness. If you do this, you will only be missing the "Decel" function. Everything else will work fine.

            The only thing missing is a schematic of the system. I will add that in the next post.
            Last edited by twright; 12-22-2020, 09:50 AM.



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                This should give you a pretty good start. Hopefully, are of your parts will have come from a working vehicle and you won't have to fight with it for two weeks to get it to work.

                If the thing doesn't work when you get it all hooked up, look at the clutch and brake switch connections. The switches have to be correctly positioned and the wires have to be as specified above.
                Last edited by twright; 12-13-2020, 06:40 PM.


                  Excellent contribution.