550 Cruise Control

Wow, that is really wanting your cruise control to work. Good persistence.

 

Way too late to help, but I was able to piece together a complete diagram using the 456 diagrams after figuring out the equivalent components. I've added this wiring to the diagram below (right hand side).

ABS, ASR and Servotronics Wiring Diagram

There is just one big splice (pigtail) sending vehicle speed data from instrument panel plug "B" pin 16 to the following components:

Bilstein Suspension Unit
Servatronics Power Steering Module
Window ECU
Some kind of engine data plug to the right of the footwell relay/fuse panel.

Plug B pin 16 gets it's information from the Digitek module (smallest plug, pin 2). According to the workshop manual, there are three pins on the Digitek unit devoted to speed output. One goes to the speedometer, one goes to the items above and the third goes to a "Connector for engine signals" (Component 285). Not sure what the last one is. The speed signal is generated by wheel speed sensors and the ABS ECU sends this data to the instrument panel Digitek module.

 

Very Nice Work! Your chart has amazing resolution AND COLOR. I'm sure this will help others with future ABS and suspension wiring issues. As for a source for Cruise Control units, the Steering ECU still looks to be the least complicated source and it's proven.

 

Thanks!

I'll update it periodically as I become more familiar with the car. I've just added a power line to the brake (pedal) switch to show the blue wire is positive (and not the red one). Just click the link above and use your browser refresh button as required.

Cheers.

 

I’ve recently acquired a beautiful 456M and have a 4 week, 1,500 mile road trip through Belgium, Germany, Austria, Italy and France scheduled for July.
Any updates to the Cruise Control installation? Especially anyone have experience with a 456?

Thanks,

Matt

 

Components:
· Rostra 250-1223 Universal Cruise Control kit (mechanical throttle)
· Rostra 250-4206 Clutch Disengagement Switch (for cars with manual transmissions)
· Rostra 250-3742 Cruise Control Switch (left-hand mount on steering column).
[Rostra offers other switch options]
· Optional: Painless Performance CirKit Boss Auxiliary Fuse Block/3-Circuit Kit

The engine bay layout for the Ferrari 456 is similar to the 550. Both engines have the same displacement. The 456 nomenclature is based on cubic centimeters for one cylinder where the 550 is derived from the total cubic liters of all 12 cylinders. The throttle linkage appears to be in the same location. The following steps apply to cars with their steering wheels on the left.

The installation is comprised of eight sections:

1. Engine bay Control Module mounting
a. Set the dip-switches in the control module ON for switches 3, 5 & 10 (all others OFF). The Rostra installation manual has descriptions for each dip-switch.
b. Locate space towards the left-rear of the engine bay to mount the control module. The throttle cable should point to the rear of the car so it is able to arc across the firewall and then route forward so it can be connected with the throttle bracket under the left-hand throttle body.
c. Trial fit the Module Bracket (included in kit) to the Control Module and to an appropriate bracket in the engine bay. Attach the bracket to the Control Module and then to an engine bay bracket. I attached the Control Module to the left side of the power steering reservoir bracket (Module Bracket in a vertical orientation).

2. Engine bay Throttle linkage
a. Removing the LH throttle body is unnecessary but removing the LH throttle body will provide addition working room. If you remove the throttle body, have a new O-ring seal on hand. Always place rags/towels under any working area to prevent dropping parts onto the underbody pan (and having to remove the pan to retrieve them – not fun).
b. Alter the Cable Bracket by bending the longer leg over onto itself so the bracket could be attached to the existing throttle bracket at one end and to the brake vacuum bracket at the other end.
c. Attach the Cruise Control cable to new bracket so that the Cruise Control cable runs parallel to the existing throttle cable.
d. Remove the throttle cable retainer from the throttle body. Use the 3-bead connector (eyelet with two bendable prongs) and add to the throttle body. Reattach the retainer. Following the Rostra instructions to provide the correct parts and spacing to finish connecting the Cruise Control cable to the throttle body.
e. Reattach the throttle body (if removed).

3. Engine bay Wire Harness routing and installation
a. Remove the rubber wiring harness plug from the firewall and add the Cruise Control harness to pass into the car cabin. Replace the firewall plug.
b. Attach the Ground wire to a “substantial” location. Verify that there is no resistance. If the ground is not “substantial”, the unit will disable immediately after engaging (speed set). The voltage must get to the unit but must also get back to the grounded car part to complete the circuit.

4. Steering column Switch installation (Rostra offers other switch alternatives)
a. Determine where to mount the Cruise Control Switch on the left-hand side of the steering column (use masking and a marker pen).
b. Remove the steering column plastic cover. Drill a hole to fit the switch. Add a curved washer or sheet metal piece to the inside of the steering wheel column cover for additional support before mounting the switch. Route the wire harness down the steering column.
c. Reinstall the steering wheel column cover.

5. Brake Pedal Disengagement Switch installation (existing car part)
a. This switch maintains an OPEN condition until the brake pedal is pressed when the switch becomes CLOSED.
b. If the clutch switch (below) is not installed, the 12v+ wire from the brake switch is joined to the RED (C) wire on the column switch (part of the 4-block controller). The other brake switch wire is connected to the VIOLET (D) wire on the control module. See the instructions.

6. Clutch Pedal Disengagement Switch installation (optional part for manual transmissions)
a. Mount according to the instructions
b. This switch maintains a CLOSED condition until the clutch pedal is pressed when the switch becomes OPEN.
c. The wiring for this switch must be added to the Brake switch circuit. Add this clutch switch between the VIOLET wire (D) from the Cruise Control Module and the brake switch negative wire. Therefore, the negative wire from the brake switch connects with one of the wires of the clutch switch. The other clutch wire connects with the VIOLET (D) wire from the cruise control module harness.

7. Optional Fuse Block installation
a. Find space for the new Fuse Block in the passenger compartment foot-well. Remove the carpeting and release the two attachment screws that hold the metal access panel to the floor.
b. Run a wire directly from the battery to the new fuse block. The fuse block contains a relay that powers the fuse block from the ignition switch Accessory setting.
c. Place a 10 amp fuse into one of the fuse block slots and connect to the BROWN (B) wire on the Rostra Control Module.
d. Place a 4 amp fuse into one of the fuse block slots and connect to the RED wire on the control switch 4-block wire connector.

8. Vehicle Speed Sensor (VSS)
a. Sorry, after doing some research the 456 doesn’t have a separate steering ECU. You’ll have to determine where to get a speed signal.
b. For the 550:
i. Rostra Control Module GRAY Wire (F)
ii. The VSS can be obtained from the steering ECU located in the passenger fuse panel compartment.
The steering ECU is a relay-sized plastic covered device located in the fuse compartment near the central drive-shaft tunnel. On the 550, the ECU pole is labeled “V”. The wire color in the base connector block is WHITE.

 

Doesn't a) contradict ii)?

The VSS (vehicle speed?) is usually found on a white wire with a yellow stripe. I think the 456 has two types of steering unit.

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I'm not a Ferrari mechanic. I have owned a 550 for 6 years and have done a few upgrades. The information I provided was the best I have and yes, specific for a 550. You'll have to carry-on from here. If the speed (VSS) source in your provided diagram doesn't work-out, Rostra does offer a kit that provides a sensor pickup from magnets placed on the drive shaft. I've used this option on a '57 Thunderbird successfully for 20 years. The challenge with adding features to vintage Ferraris is that you have to do some of the very detailed work yourself - there's just no information available. Even if you start the installation and can't get it operational before your July trip, you are still able to take the trip. You may need a leg massage at the end of each day, but you'll still complete your trip - just keep your eye on the speedometer, the cars do like to run.

 

If I remember correctly, Ferraris of this era send data from the speed sensor to the instrument panel... and the instrument panel divides the frequency by two to send to all the other devices/computers on the car.

I don't know if the Ferrari speed sensor puts out twice the rpms as your speed sensor?