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rover_75
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Discussion Starter · #1 · (Edited)
After much research I have determined that - it should be entirely possible to add cruise control to the 75/ZT with the CDT engine without major work.

I really want to do this, so I'm embarking on this mission, If I can do it, I'll provide pictures and a guide for anyone else interested, but it is early days.

Here's what I've found -

The CDT engine management contains the cruise control logic, the only bits that need to be added are a Cruise Interface Unit which goes behind the passenger fascia in the dashboard. This unit takes input from the cruise master switch (which can be added to the dashboard - or simply bypassed) and the steering wheel controls. It interfaces with the ECU on the CAN-bus and also outputs a signal for the instrument console to display the Cruise Control light. On manual cars it may also require a clutch switch (which looks identical to the break switch as far as I can see) and on the auto models, it will require a signal to go to the gearbox control unit to put it in CC mode.

So, the basic parts required are -

M47 Diesel Cruise Interface Unit
Steering Wheel Controls
Master cruise control switch (Optional)

and any wiring that may not exist on non CC models. Probably a loom to go from Interface unit to steering wheel switches... I don't know about the can bus link to the ECU, but it may already be there - if not, a part number will need to be found too.

With just the Cruise Interface unit connected to the ECU I could probably mock-up steering wheel switches to simply prove that no reconfiguration of the ECU is required.

Can somebody help me get part numbers for the m47 diesel cruise Interface unit and Cruise control steering wheel controls as a first step and then point me in the direction of how to obtain these from MGR or their suppliers, can I simply ask at the local dealership?

Thanks,

- William
 

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Finding a component behind the dash sounds scary, Will. I have a 2002 75 with cruise which I would like to transfer to a new 75 without. My wife has taken over the first one and doesn't use cruise. The second car was brand new but from stock, I took delivery on the day the Administrators were called in to Longbridge. I do use the cruise and I would like to know if it would be possible to transfer. I wouldn't think you would be able to retro fit the steering wheel switches without a great deal of aggro. Think airbags! It would be easy to fit new switches somewhere else. Please keep me posted of your progress.
 

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What about the clutch and brake pedal switches?


I'd be very interested in hearing your progress....a tricky job indeed.
 
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All youneed is a speed signal and somehwere to attach the throttle drive cable (direct to the throttle peadl on drive by wire)
 

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rover_75
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Discussion Starter · #7 ·
Major Ingram said:
What about the clutch and brake pedal switches?


I'd be very interested in hearing your progress....a tricky job indeed.
The break and clutch (manual only) switches are already there on the CDTs and feed into the ECM for the purposes of reduced engine surge during gear changes (clutch switch, manual only) and quick reduction of fueling (braking).

The plot thickens...
 

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rover_75
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Discussion Starter · #8 ·
Bixie said:
Finding a component behind the dash sounds scary, Will. I have a 2002 75 with cruise which I would like to transfer to a new 75 without. My wife has taken over the first one and doesn't use cruise. The second car was brand new but from stock, I took delivery on the day the Administrators were called in to Longbridge. I do use the cruise and I would like to know if it would be possible to transfer. I wouldn't think you would be able to retro fit the steering wheel switches without a great deal of aggro. Think airbags! It would be easy to fit new switches somewhere else. Please keep me posted of your progress.
My main concern is the rotary coupler - will it have the neccersary pathways for Cruise control or are there different couplers/wheels for cc and non-cc models...

I'm hoping its all standard, and only the switches need to be fitted and wired up to the coupler.

Airbag is not a problem.
 

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rotary couplers are the same i beleive although a check on on epc would confirm this. i presume the harness the other side of the coupler is the same but i would expect the problems to be there if anywhere.

Once you have all the necessary parts in the car, it will need to go on testbook to have the cruise option turned on.
 

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also i dont see how the master cruise switch could be optional. when the ignition is first switched on the cruise always defaults to off. The master switch is not a mechanically latching switch. the latching is in the software of an ecu somewhere.
 

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rover_75
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Discussion Starter · #11 ·
MattL said:
also i dont see how the master cruise switch could be optional. when the ignition is first switched on the cruise always defaults to off. The master switch is not a mechanically latching switch. the latching is in the software of an ecu somewhere.
The master switch is latching, not the ECU so it can be bypassed. The simplest way would be to take the feed from the fuse box to ECU and spit it and run it into the master switch input on the ECU.
 

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Discussion Starter · #12 ·
MattL said:
rotary couplers are the same i beleive although a check on on epc would confirm this. i presume the harness the other side of the coupler is the same but i would expect the problems to be there if anywhere.

Once you have all the necessary parts in the car, it will need to go on testbook to have the cruise option turned on.
How would I get access to TestBook, persuade a Rover dealership to switch the option on? Or do one of us (on the forum) have access to TestBook?
 

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think dealership is the only option. Personally i would loiter and try and grab one of the technicians rather than go through the service desk. Im lucky in that in the past i have managed to get it done at work. I work at LR who have the same system. Remember seeing an option to have the FBH on/off Cruise on/off or traction on/off. Along with a few other options. Its a shame i cant really do it anymore.

Has anyone on here got any T4 discs for the 75?
 

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Discussion Starter · #14 ·
MattL said:
think dealership is the only option. Personally i would loiter and try and grab one of the technicians rather than go through the service desk. Im lucky in that in the past i have managed to get it done at work. I work at LR who have the same system. Remember seeing an option to have the FBH on/off Cruise on/off or traction on/off. Along with a few other options. Its a shame i cant really do it anymore.

Has anyone on here got any T4 discs for the 75?
not a problem, i want to have some dealer options enabled anyway.
 

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rover_75
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Will, any update regarding this?

I am thinking of starting to do this also. Unless somebody has an aftermarket model installed and is happy about it.
 

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I am looking on with interest as my 75CDt has cruise but doesnt work anymore. the master switch lights up though. I had the pedals checked but they were ok. It first only worked intermittently and eventually it gave up.
 

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Probably the steering wheel switches. I would be testing these if i were you. Airbag off and get the continuity tester on to the multiplug for the switches.
 

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Discussion Starter · #20 ·
No progress on this yet. I've been busy with another project for my Rover 75 involving adding lots of additional wiring and components to the car, the results of which I'll post seperately when complete.

I still need to get hold of the cruise interface unit, which I need a part number for.

- William
 
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