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65 Posts
Discussion Starter · #1 ·

This has been a pretty popular mod over the years I thought I would share with you guys as this should work on pretty much any Ford vehicle( obviously using different wires circuits depending on year).

I found this to be the best set up and will work for several years, late 80s up. You will have control of line lock with one hand on steering wheel while the other is on shifter(manual)

This is how to wire the Hurst line lock to work off the cruise control “off” button located on the left side of steering wheel. On my 2003 Mach 1 the cruise control wires run into a grey plug located to the right of the steering wheel under the dash. It’s a blue wire with black dashes I’m sure it’s the same for different year Mustangs just make sure you test it.

You will need a multi-meter, a regular automotive switch (several to choose from so pick the one you like). I used one that had a light so I knew when it was armed to run the line lock. You will also need 2 single pole, double throw relays (spdt). These relays MUST have the 5 leads in order to work. The first thing you will need to find is the wire from your cruise off button which is a momentary switch( provides ground only when depressed and held (see above). You know you've found the right wire when you set your multi-meter to continuity and hear the continuity tone when you press the button (don't forget to ground one of the test leads from your meter and use the other lead to test the wire).

Once you've located the right wire, cut it. Now you have 2 wires but you need to know which one comes from the cruise off is that going to be possible? Use the same test as above and the wire that shows continuity to ground when the cruise off switch is depressed. The other half of the wire goes to the cruise control module and will also be connected to one of the relays. You can also test for the button by unplugging the wires prior to any cutting and then you will know on what side of the plug the button is on. Relays if properly wired are used to control high voltage/amperage circuits using a switching circuit so little load is required and smaller wires such as cruise control switches/circuits do not get overloaded from high currents running thru them, this is the reason for 2 relays.

Also cruise control will still operate normally

The relays will have a diagram and PIN numbers

On them.

Drawing attached below

Now lets start making our connections to the relays.

Relay # 1

1. 86 goes to ground

2. 87 goes to relay #2 terminal 86

3. 85 goes to The positive output from arming switch and will provide 12 volts to leads 85 when turned on.

4. 30 goes to cruise control off button(grounds when off button is depressed)

5. 87a (the center lead) goes to the the other end of blue wire with black slashes which in turn runs to the cruise control module. If everything works right, when your Arming switch for line lock is in the off position, your cruise control should function as normal. When you flip the switch, the circuit has been armed and will work by pressing and holding cruise off button, you should hear the relay click and will send power to line lock. What we want is for the relay to only send a 12v signal to the line lock while depressing the cruise off button when arming switch is turned on.


6. 86 connects to relay#1 pin 87( will complete ground thru cruise of switch)

7. 85&30 Connects to switched 12v(power from armed switch when on)

8. 87 to line lock 12v positive

9. 87a not used on relay#2




I know drawing is not the greatest but you can visualize what goes where


65 Posts
Discussion Starter · #3 ·
Separate switch works well too, I was trying to conceal it and having my left hand on the steering wheel holding button while my other hand shifts thru the gears.
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