Defender cruise control not working with 1.2 ratio transfer box

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Buckhandle

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I understand that fitting a cruise control to a Defender can be a problem if it has a Disco transfer box fitted (1.2 ratio). I'm actually in the progress of completing a DIY version of the cruise control so I've not yet been able to confirm the problem.

However, there are a few threads out there stating the problem, but so far I've found no-one with a solution. Most info I've found is 3-5 years old.

Maybe the rev input vs actual road speed will be 'off' some standard values thus disengaging the cruise control. However one of the leading LR re-map provider says it may be more complex as they looked into this earlier without finding a solution. There was not obvious link between the rev and road speed in the software which could be altered.

Has anyone any knowledge of how to get around the problem?
 
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Hi Buckhandle

I too am interested in CC, and was toying with an overdrive (wife wont sanction expense :( ).

If you have a standard transfer box then you can simply add four wires and two switches. Unfortunately the ECU compares road speed with engine revs and as you say with the potential higher road speeds of the 1.2 gearing it goes out of parameters and dissengages.

There are some complete kits that claim to resolve this, the main one is the mobile centre one which includes its own ECU, what it does I do not know, but it must trick the engine ECU back into correct parameters.

Defender Td5 Cruise Control [407TD5CCK] - £349.99 : LED Lights, Marker Truck LED Vehicle Lighting Trailers Commercial Lightbars Warning Lights Land Rover

Again though at £350 for the TD5 one I don't think I could sanction it, especiall as I have the standard gearing and for a few quid can use the existing ECU. This is quite a useful thread to look at on how to install one.

Defender2 - View topic - Cruise control episode 3 The end!
 
Surely if you had the gear to read everything and remap a TD5 ECU, you would be able to reset the parameters for the cruise control if you could figure out where it was in the coding.

I really want cruise control on mine too but already have a disco transfer box and not giving that up. Its a pity as the cruise control nearly goes hand in hand with a disco transfer box as you'll want both if your doing longer spins that warrent cruise control.
 
Hey KillaJoules,

You are right, this is what Ive learned too. I am for sure not interested in a £400 kit ..
The DIY option (wires + switches is less than £10) is obvious - except it does not work ... :)

There has to be an alternative for less money..

Lars
 
Surely if you had the gear to read everything and remap a TD5 ECU, you would be able to reset the parameters for the cruise control if you could figure out where it was in the coding.

I really want cruise control on mine too but already have a disco transfer box and not giving that up. Its a pity as the cruise control nearly goes hand in hand with a disco transfer box as you'll want both if your doing longer spins that warrent cruise control.


... you hit the nail.

' .. if you could figure out where it was in the coding'

This is the challenge. As I was told, there is no obvious link in the coding which connects the rev and road speed.
 
Yep. That's the tricky bit alright, its extremely difficult to distinguish different parts of the codes on an ECU map unless you really know your stuff. Grand comparing very differences between different maps if you have the gear to pick them out and know what they must be so you can single them out as use differently but actually trying to find a code for something specific like parameters for the cruise would be near impossible me thinks :(

Where in Ireland can you use cruise control? Not many miles of motorway.

Ah, we're not that bad :p

I live just off the main Cork-Dublin Motorway so half hour to Cork or 2 hours to Dublin which I do fairly often would be nice if I didn't have to keep my foot on the pedal as the Defenders seating position isn't the most comfortable to begin with :p

Handy too for towing the trackcar and offroader on the motorway as the 110 really doesn't like to sit at 50mph so your always watching it as its more comfortable towing at 60-65 with the longer gearing... Different turbo may help that though

Plus, any slight lift on the pedal has you almos come to a stop in something that is about as aerodynamic as a ships sail :D
 
So .. I'm considering to change the signal from the speedometer sensor on the transfer box.

90/110 speedo drive gears
frc3310 blue ------- 20 teeth -- 7.50,235/85 or 255/85 tyres 20D & 22D transfer box
frc3311 green ------ 21 -- all 90 vehicles excepth the 50th ann edition.
frc3312 yellow ----- 22 -- 90 with 205 x 16 tyres
frc3313 red -------- 24 -- 32D transfer box (1.22 ratio)

I will change the to the 24-teeth version. I imagine it will change my speedo reading to be lower than actual. Not good, so I may have to rely on the GPS reading then..

Any comments?

Lars
 
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Seems a lot of messing about just to get a working cruise control that may only be used little. But its your motor so why not give it a go.

Personally I love CC, given my commute is 9 miles a day at 60 mph on the A41 with no stopping then if I have the wifes Peugeot I always use CC, I also had a 300 tdi Disco ES a few years ago with CC which was excellent, except the vacuum pump would occasionally stall which required removing the fiddly wee swine, opening up the vacuum chamber, spinning the motor manually and then refitting to LR.

I peronally would use CC often, so at some stage will install it. Just time and money at teh moment.
 
9 miles is perfect for a cup of coffee ;) and a relaxed cruise control drive ..
I mainly use my car for longer distances and town trips. But often its 150+ miles..
 
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Personally I love CC, given my commute is 9 miles a day at 60 mph on the A41 with no stopping then if I have the wifes Peugeot I always use CC, I also had a 300 tdi Disco ES a few years ago with CC which was excellent, except the vacuum pump would occasionally stall which required removing the fiddly wee swine, opening up the vacuum chamber, spinning the motor manually and then refitting to LR.

I peronally would use CC often, so at some stage will install it. Just time and money at teh moment.

You have to be joking:mooning::mooning 9 miles and need CC...Really:rolleyes: CC is more for auto matics as they can down shift when needed. Standard/stick shift do not work, as you stand a chance of high revving your motor if you need to down shift.
 
Sounds like you have never used cc on a manual, works well on our 307 hdi 6 speed manual

As soon as you touch the clutch or brakes cc is disabled. Obviously if the load increases significantly then yes an auto can respond with kickdown, but a manual requires driver intervention then.

Obviously it is best for longer journeys but nice for a short pootle too :cool:
 
So here we go. The cruise control works fine now. I fitted a new frc3313 to the transfer box .. It did the trick. Only problem now is a 10% misreading on the speedometer ..
 
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