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Electronic Cruise Control Page 1
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This page was developed to show one how to convert over to the late model GM electronic cruise control. While it may be possible to use the older style cruise control, at the time I wrote this, I did not investigate whether this was possible, due to the fact the the cruise throttle cable may not be compatible with the TPI throttle body. While it may be possible to do, it is not mentioned here.
The point here is that even if it was possible to use the older "split cable" set up and cruise module, it is obsolete, and many pieces may not be available, even new.. Parts, even in a salvage yard, are more than likely to be worn out or broken. If you are able to use the older system modified to use on TPI, e-mail me, and I will build a special page for it and the the author credit for it.
The newer system, used on vehicles since around 1981 or so, each much more common. Since these systems depend on a VSS to operate, and if you have installed a full function TPI, you need the VSS anyway for proper operation of many devices controlled by the ecm that also affect engine performance.
The new system is simpler in terms, that you have vacuum line and wire harness combination, control module, vacuum servo, cruise cable and the actuation switch on the turn signal stalk.
The picture above shows the typical late model cruise harness. (A) Harness which includes the vacuum line from cruise vacuum servo to brake switch. (B) Electronic module. (C) Vacuum servo connector, next to it is the vacuum line that goes into it. (D) Modified cruise control turn signal stalk (E) This switch deactivates the vacuum, also has electrical connection for the TCC on the 2004R or 700R4 transmissions. (F) The brake switch which has the connection for the cruise control electrical activation. Both "E" and "F" are widely available. Take your continuity tester with you to the salvage yard to check out your parts. Part "B" cannot be easily checked, however, the circuit board can be easily removed from plastic case. (G) Is the connector that has the wires to hook up the unit.
The picture above shows the vacuum cruise servo and bracket. Not shown is the smaller vacuum line that must be tied into engine vacuum so the module operates.
Above shows typical cruise control circuit. Use this as an aid in troubleshooting.
Above is the main electric hookup that is located under the dash. You can either cut the terminal block off and tie the connections in directly OR get the male end connector, so if for some reason you need to remove the main harness, you can do so without disturbing the rest of the harness (recommended).
The picture above shows the other two important connectors under the dash. (A) Is where the wire lead from the turn signal stalk cruise control switch is connected. (B) Connects to the brake switch.
The most important thing is to modify your turn signal stalk to accept the cruise control switch. The early cruise control systems used a switch that had only three wires that plugged into the cruise control connector. This will not work with the electronic cruise control.
If your vehicle was originally equipped with cruise control, you'll have to remove the turn signal stalk so it can be easily modified. But, before you remove the stalk, gain access from under your dash to your original cruise plug in, tie a string or thin wire to the old plug in and as you remove your turn signal stalk, you pull this guide wire up through the hole to make it easier to install the new wire harness.
You will have to remove your steering wheel to gain access to the screw that holds your turn signal/cruise stalk in place. Follow the recommended procedures in your automotive manual in removing your steering wheel.
If your vehicle was not originally equipped with cruise control and you want to have one, you'll have to find a vehicle that was originally equipped with cruise control OR you'll have to drill a hole in the back side of cruise control switch housing above where it pushes into the stalk and run the wiring on the outside and then down through the access hole for the wire to travel down the steering column housing to under the dash.
For the main harness, you'll have to drill a a hole big enough for the main harness to go through the firewall. Just be careful where you drill your hole, look on both side before you decide to drill, and even then use a small 1/16" bit and run a wire through to see where it ends up at and that you have plenty of maneuvering room for the harness to be installed. When you have where you want the harness to go through, cut the hole just big enough so the rubber grommet will fit. Use a hole size or knock out punch the proper size.
Mount the vacuum cruise servo in a place where it will not interfere with closing the hood, usually on the inner fender well, like I did on my Camaro.
Another consideration is the length of the cruise control cable to the throttle body. Take this in consideration as where you mount the servo module. This is critical, as when the cruise control actuates you don't want it too tight or loose so it will hold the preset speed properly. The cruise cable and bracket I found that works is the one that is used on the 87 and later FWD GM with the 2.8Land 3.1L V6.