I fitted a cruise control kit to the TF 160. The kit I used was the Waeco MagicSpeed MS 50, purchased from Conrad Electronic.
Steps to fit the kit:
- Find a place to mount the control unit.
- Install the vacuum servo that opens/closes the throttle in the engine bay.
- Add a switch on the clutch pedal.
- Connection to the brake light switch.
- Speed signal.
- Earth and +12v feed.
- Control panel (On/Off/Set/Reset and telltale LED).
On the TF, I went one step further with the control panel and integrated the kit with MG Rover OEM steering controls taken from a ZS. More on this later.
Mounting the control unit
With the dashboard out, I was able to easily mount the control unit in the driver's footwell, above the Window Lift ECU. Note, while I was able to get the dashboard back in over the cruise control module, it's a very tight fit and the module would fit better mounted horizontally and/or lower down.
Fitting the vacuum servo
My TF 160 had the small vacuum canister fitted that's used to power an exhaust volume control valve. Like most TFs I guess, this valve was disconnected long ago. I removed the canister and vacuum lines connected to it and used the canister's bracket to mount the cruise control servo. Fits perfectly. From there, the servo's cable was run around the engine, following the accelerator cable and attached to the throttle. The cable was very long, to allow various installations, so I cut it to size using a Dremel and fitted a bicycle brake cable end cap to protect the end of the cable jacket. I took the simplest approach to secure the cable - using a clip, supplied with the kit, to clip it to the accelerator cable. I'm not 100% happy with this as the mount can flex and I believe the cruise control system will perform better with a more solid mount point. I'll revisit this later.
The wiring for the servo was run alongside the accelerator cable down the sill, through a crossbeam underneath the seat (using a plastic protection to avoid chafing on sharp edges), up towards the engine bay hatch and through the same grommet used for the accelerator cable. At that point it can be connected to the servo.
Clutch pedal switch
The cruise control module must deactivate when the clutch pedal is pressed. The kit includes a magnet and small reed switch to be mounted over the clutch pedal. I used the bolt for the brake light switch to mount the bracket and angled it towards the clutch pedal. I cut down the corners of the bracket so it wouldn't interfere with my left foot while driving :)
Brake pedal switch
The existing switch for the brake lights was used and spliced into the cruise control unit's loom, along with the clutch switch, according to the wiring diagram included with the kit.
The module regulates the car's speed and so requires a way of monitoring it. The kit provides 2 ways of doing this: using a transducer mounted next to a driveshaft, or using an electronic feed from the car's speedometer. The transducer option seems to be the most commonly used method, in fact, I found that the electronic method was very poorly documented in the installation instructions.
From forum posts and wiring diagrams, I found the white/orange wire on the loom to the dash instruments carries a speed signal. I spliced into this wire just next to the passenger fusebox.
Initially, the cruise module didn't work with this speed signal. There is a black wire loop on the module that can be cut to change an internal setting for the speed reading. Again, there was almost no documentation on this in the instructions, but cutting the loop fixed the problem and the system worked perfectly.
Earth and +12v feeds
I used the earth point right above the module for the negative feed. I cut the wire down, as it was much longer than required.
The positive feed in the kit includes a fuse. Again, I shortened this and connected it using a spade connecter on one of the spades on the passenger fuse box.
The control panel
My goal all along was to integrate the kit with MG OEM cruise control buttons. To do this, I broke open the kit's controls to discover how the switches are wired. There are 4 wires to the buttons unit:
- Set/Reset (one wire with an inline resistor on one of the buttons)
- Power button
- +12v for the LED
- Earth for the LED and buttons
Similarly, I tested the OEM controls which use 3 wires:
It was quite easy to integrate the OEM controls, cut and splice and add a resistor inline with one of the buttons.
The only missing element at this stage, was the on/off button and telltale LED. There is no OEM button for this on the TF. I've seen a lot of people modifying a fog light button for their cruise control, however this isn't an option for me, as I have all the factory options on the centre console (front/rear fogs, HRW, aircon) :) I opted for a push button with integrated LED from Maplin, mounted on the dash to the right of the steering wheel. Works great!