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Yawn, Cruise fault thread
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EdinWarren
 


Member Since: 15 Apr 2019
Location: Edinburgh
Posts: 32

United Kingdom 2010 Discovery 4 3.0 TDV6 XS Auto Santorini BlackDiscovery 4
Yawn, Cruise fault thread

Sorry guys, I know there are many faults on cruise, I cant find one that relates to my issues. Everything on mine appears to work, no error messages, cruise speed sets fine, but when you take your foot off the throttle, the car just slows.

No matter what you set it at nothing happens.

There have been a couple of times I thought that it was slowing less than others but cant be sure.

Any idea where to start looking? Or am I being a fud and have set it wrong?

Any hints appreciated.

D4, TDV6 XS 2010 MY
  
Post #207643516th Aug 2019 11:19 am
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Narpy
 


Member Since: 18 Jul 2011
Location: Stockport
Posts: 7830

2005 Discovery 3 TDV6 S Manual Cairns BlueDiscovery 3

Are you getting a dashboard light when you press the cruise button?
 Mods:
Front Fogs + Halos
FBH Remote Control
The 1st Ever RRS Modded Grill
Garmin Nuvi + D4 Surround + Reversing Camera.
D4 Steering Wheel.
Rear Boot Spoiler.
Twin Brake Lights.
Wing Mirror Indicator Repeaters.
Long Roof Rails
Make your own Narpy grill thread
I'm not scared, I'm outta here. 
 
Post #207645616th Aug 2019 12:41 pm
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EdinWarren
 


Member Since: 15 Apr 2019
Location: Edinburgh
Posts: 32

United Kingdom 2010 Discovery 4 3.0 TDV6 XS Auto Santorini BlackDiscovery 4

From memory, the little speedo/clock symbol comes up and the central display says cruise set to X speed.

As soon as you touch the brakes or throttle, it goes off.
  
Post #207649816th Aug 2019 3:52 pm
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Narpy
 


Member Since: 18 Jul 2011
Location: Stockport
Posts: 7830

2005 Discovery 3 TDV6 S Manual Cairns BlueDiscovery 3

It should go off if you touch the brakes, that's normal.
Throttle however, it should stay on.
 Mods:
Front Fogs + Halos
FBH Remote Control
The 1st Ever RRS Modded Grill
Garmin Nuvi + D4 Surround + Reversing Camera.
D4 Steering Wheel.
Rear Boot Spoiler.
Twin Brake Lights.
Wing Mirror Indicator Repeaters.
Long Roof Rails
Make your own Narpy grill thread
I'm not scared, I'm outta here. 
 
Post #207650116th Aug 2019 3:58 pm
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EdinWarren
 


Member Since: 15 Apr 2019
Location: Edinburgh
Posts: 32

United Kingdom 2010 Discovery 4 3.0 TDV6 XS Auto Santorini BlackDiscovery 4

Basically, theres no attempt to maintain the speed of the car, it just drops off straight away. It says speed set to 70mph but the second you take your foot off the throttle, the car starts slowing and the engine revs drop.
  
Post #207650816th Aug 2019 4:28 pm
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Narpy
 


Member Since: 18 Jul 2011
Location: Stockport
Posts: 7830

2005 Discovery 3 TDV6 S Manual Cairns BlueDiscovery 3

Does the cruise light go out when you take your foot off?
 Mods:
Front Fogs + Halos
FBH Remote Control
The 1st Ever RRS Modded Grill
Garmin Nuvi + D4 Surround + Reversing Camera.
D4 Steering Wheel.
Rear Boot Spoiler.
Twin Brake Lights.
Wing Mirror Indicator Repeaters.
Long Roof Rails
Make your own Narpy grill thread
I'm not scared, I'm outta here. 
 
Post #207650916th Aug 2019 4:35 pm
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EdinWarren
 


Member Since: 15 Apr 2019
Location: Edinburgh
Posts: 32

United Kingdom 2010 Discovery 4 3.0 TDV6 XS Auto Santorini BlackDiscovery 4

No, it behaves as if its holding speed.
  
Post #207651216th Aug 2019 4:45 pm
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EdinWarren
 


Member Since: 15 Apr 2019
Location: Edinburgh
Posts: 32

United Kingdom 2010 Discovery 4 3.0 TDV6 XS Auto Santorini BlackDiscovery 4

Ive been out in the car to test this and heres what happens

Press Set and green clock icon appears. Set speed displays correctly.

Take foot off throttle car immediately slows. No change on dash.

Press the plus/set button, to try to add to the speed, the set speed goes up. Car does not speed up as if throttle not being actuated.

Eventually have to press the throttle pedal and the message changes to cruise cancelled or similar.

Puzzled

Any help would be appreciated. Does this sound familiar to anyone?
  
Post #207722819th Aug 2019 7:12 pm
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Famousfive
 


Member Since: 12 Aug 2014
Location: Southampton
Posts: 1806

Ukraine 2013 Discovery 4 3.0 TDV6 GS Auto Loire BlueDiscovery 4

Not heard of this before, especially as the control unit is registering the speed being set on the cluster.

No fault codes from IID or similar either?

Std fault finding issues:
1) rotary coupling
2) Steering wheel switches
3) Check the continuity on steering wheel loom
4) check connections on the pcm module behind the battery
5) brake pedal switch, check rear brake lights are working

IIRC the cruise is controlled by a vacuum and it sounds like its that what is failing ... but I’m no mechanic and don’t know how you diagnose if it was, sorry.

Hopefully an expert will be along shortly Thumbs Up
  
Post #207725219th Aug 2019 7:52 pm
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EdinWarren
 


Member Since: 15 Apr 2019
Location: Edinburgh
Posts: 32

United Kingdom 2010 Discovery 4 3.0 TDV6 XS Auto Santorini BlackDiscovery 4

Quote:


Not heard of this before, especially as the control unit is registering the speed being set on the cluster.

No fault codes from IID or similar either?

Std fault finding issues:
1) rotary coupling
2) Steering wheel switches
3) Check the continuity on steering wheel loom
4) check connections on the pcm module behind the battery
5) brake pedal switch, check rear brake lights are working

IIRC the cruise is controlled by a vacuum and it sounds like its that what is failing ... but I’m no mechanic and don’t know how you diagnose if it was, sorry.

Hopefully an expert will be along shortly Thumbs Up


OK

Rotary coupling
I dont have any issues with anything else on the rotary coupling, and normally turning the wheel to a different position would allow the fault to be temporarily cured, but to no avail. Could be but not looking likely as the indications all look OK. Not discounting this yet.

Steering Wheel switches
Everything works as expected

Steering wheel loom
Will need to research this one. Thanks.

PCM Module

Need to check this one, thanks.

Rear lights/Brake switch

I have a new one to fit which I hope to do this evening if my kids let me have time. Brake lights work fine but are very very sensitive. I've a hairs touch to activate the brake lights. I have to push the pedal a fair bit further to move the handbrake as well. Looking into this one.

IIRC

I don't have this, I have the iCarsoft LRv2, the widescreen fella.

What systems would I check to diagnose this? There are so many!!

Vacuum

This could be the problem as the brake pedal responds well when I'm driving and after stopping the engine and restarting a few minutes later the brake pedal is brick hard like the vacuum has leaked away. I will need to dig into this one also. Thanks.

Cheers

Warren
  
Post #207742120th Aug 2019 2:56 pm
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swansty
 


Member Since: 21 Sep 2008
Location: Northern Ireland
Posts: 914

Northern Ireland 2010 Discovery 4 3.0 TDV6 XS Auto Zermatt SilverDiscovery 4

I had the hard brake pedal symptom although it took a few hours before the pedal was hard - new servo cured that
  
Post #207757821st Aug 2019 8:54 am
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EdinWarren
 


Member Since: 15 Apr 2019
Location: Edinburgh
Posts: 32

United Kingdom 2010 Discovery 4 3.0 TDV6 XS Auto Santorini BlackDiscovery 4

Sounds like it may be vacuum or servo related then?

Thanks

Warren
  
Post #207763821st Aug 2019 1:07 pm
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Flack
 


Member Since: 06 Sep 2006
Location: Preston Lancashire
Posts: 6224

England 2007 Discovery 3 TDV6 XS Auto Stornoway GreyDiscovery 3

Has the car had the belts done?, there are some vac pipes at the rear of the engine make sure these are still intact.
They might have disturbed them if the rear belts been changed.

Flack Thumbs Up
  
Post #207764221st Aug 2019 1:32 pm
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EdinWarren
 


Member Since: 15 Apr 2019
Location: Edinburgh
Posts: 32

United Kingdom 2010 Discovery 4 3.0 TDV6 XS Auto Santorini BlackDiscovery 4

Supposed to have been done before I got the car so possibly. Thanks.

There is what looks like a vac pipe with a plug sticking up next to the nearside headlight. Its just flapping about. It has a wee cap on the end with a cross it.

Ill be checking the vac lines when it stops raining. Whats the access like at the back of the engine?
  
Post #207765821st Aug 2019 3:22 pm
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Flack
 


Member Since: 06 Sep 2006
Location: Preston Lancashire
Posts: 6224

England 2007 Discovery 3 TDV6 XS Auto Stornoway GreyDiscovery 3

Quote:
Whats the access like at the back of the engine?


Bad , there are also a some vac pipes at the front of the engine, if you look on the top right hand facing the engine, you will see a bracket with a valve, it has a couple of pipes and plug attached to it, check these out. They go across the front of the engine and branch off to the rear and down the drivers side to the secondary turbo, all these get moved when belts are done.

Flack Thumbs Up
  
Post #207766121st Aug 2019 3:54 pm
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