Disco 2 Disco 2 Cruise Control Not Working

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keremctnr

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Hello All,

I know this topic may have been covered couple of times, I have been searching but may need additional help to understand what to do as also I am not a very mechanic guy let me say.

I was not bothered with the cruise not working but after I fixed many things now my OCD does not allow me to be comfortable without it working
lxvR5hR.png


So, my button works, when I click the button an amber light comes on to indicate that its turned on but my steering wheel buttons does nothing, it does not fix it. I have been checking the topics about the actuator and the cables and checking the manuals, but I would be happy if you can also give some light on what can I check more? I wanted to fix this myself without taking it to a shop but lets see.

Here are couple of photos that I took from the engine bay.
 

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Well so where do want to start?
The master switch illuminates so that only tells you the bulb is ok, then then you have the ECU, Vacuum pump, Actuator which you show in two pictures, Set and Cancel switches, Vacuum hose, and Brake pedal switch plus if you have a manual gearbox a Clutch pedal switch.

I think that's everything 🤔 all can have an issue to stop the system working.
The D1s ECU has a means of testing the systems pump, switches which may or not work with the D2 but the principle is the same.

CRUISE CONTROL​

Ground Test - From pin 8 (black wire) on the cruise control module plug perform a continuity test to good chassis ground

Main voltage test - With ignition & cruise control system on, transfer in high (non diff lock) & auto box in 'drive' connect volt meter between pin 8 (black wire) and pin 10 (white & yellow wire) you should have battery voltage if not check fuse

Secondary voltage test - Connect volt meter between pin 8 (black wire) and pin 9 (Purple & Green wire) you should have battery voltage if not check lock out relay or gear selection switch.

Brake Pedal Test - Connect volt meter between pin 8 (black wire) & pin 5 (green & purple wire). Press the brake pedal, you should get battery voltage.

Steering Wheel Set / Accel Test - Connect volt meter between pin 8 (black wire) & pin 3 (red & white wire). Press the Set / Accel button, you should get battery voltage.

Steering Wheel Res / Cancel Test - Connect volt meter between pin 8 (black wire) & pin 4 (blue & white wire). Press the Set / Accel button, you should get battery voltage.

Vacuum Pump Test - Using a jumper wire connect pin 10 (white & yellow wire) to pin 1 (white & blue) this provides power to the pump. Then using a jumper wire connect pin 6 (black & yellow) AND pin 7 (black & red) to pin 8 (black wire). This should energise the pump & solenoid and the bellows should contract.

Speed Sensor Test - Connect a volt meter between pin 8 (black) and pin 11 (yellow & pink), drive the motor around the block, voltage should increase as speed increases.
 
Last edited:
discool said:
Well so where do want to start?
The master switch illuminates so that only tells you the bulb is ok, then then you have the ECU, Vacuum pump, Actuator which you show in two pictures, Set and Cancel switches, Vacuum hose, and Brake pedal switch plus if you have a manual gearbox a Clutch pedal switch.

I think that's everything 🤔 all can have an issue to stop the system working.
The D1s ECU has a means of testing the systems pump, switches which may or not work with the D2 but the principle is the same.

CRUISE CONTROL​

Ground Test - From pin 8 (black wire) on the cruise control module plug perform a continuity test to good chassis ground

Main voltage test - With ignition & cruise control system on, transfer in high (non diff lock) & auto box in 'drive' connect volt meter between pin 8 (black wire) and pin 10 (white & yellow wire) you should have battery voltage if not check fuse

Secondary voltage test - Connect volt meter between pin 8 (black wire) and pin 9 (Purple & Green wire) you should have battery voltage if not check lock out relay or gear selection switch.

Brake Pedal Test - Connect volt meter between pin 8 (black wire) & pin 5 (green & purple wire). Press the brake pedal, you should get battery voltage.

Steering Wheel Set / Accel Test - Connect volt meter between pin 8 (black wire) & pin 3 (red & white wire). Press the Set / Accel button, you should get battery voltage.

Steering Wheel Res / Cancel Test - Connect volt meter between pin 8 (black wire) & pin 4 (blue & white wire). Press the Set / Accel button, you should get battery voltage.

Vacuum Pump Test - Using a jumper wire connect pin 10 (white & yellow wire) to pin 1 (white & blue) this provides power to the pump. Then using a jumper wire connect pin 6 (black & yellow) AND pin 7 (black & red) to pin 8 (black wire). This should energise the pump & solenoid and the bellows should contract.

Speed Sensor Test - Connect a volt meter between pin 8 (black) and pin 11 (yellow & pink), drive the motor around the block, voltage should increase as speed increases.
Click to expand...

Thank you very much for this detailed tests, yes it is a D2 automatic transmission. I will check these in the due course for sure :)

sierrafery said:
Is your horn working?
Click to expand...

Stanleysteamer said:
LOL!
Love your thinking.
But as he is OCD I should imagine it is!
We'll just have to wait and see! 🤣 🤣 🤣
Click to expand...

Haha thank you both yes my horn is working and my break lights do work as well :D Yes even I have changed both my blinkers as they were not the same shade of orange after I cracked one of them, so yes if my horn was not working I would go nuts haha :D
 
keremctnr said:
my break lights do work as well
Click to expand...
The break lights are irrelevant for the CC, the N/C contact of the switch is important and you can check that only with diagnostic tool or by measuring with multimeter if the ECU gets power on pin 1(purple/green wire)...that guide which @discool posted is not valid for the D2 where pin 8 is for main power and the ground is pin 18, here's the scheme magnify it as you can:

1711611427253.png



1711611851853.png
 
Last edited:
I will keep an eye on this post!
I had similar problem with mine! But the end result was fixed by replacing the pedal assembly shaft? (Due to rust on the old one)??

Kev
 
Thank you all for the replies, I just had the time to check the car today. I did check the hose as mentioned previously, the hose was loose, when I touched it, it just fell. So I tried to cut it and put back in but that also did not worked and the hose cracked again. I believe it is too rigid now after many years, I will get a new hose and try again. Also I tested the bellows, it does hold the pressure so at least that is working in some good news :)

I also did remove the glovebox to test with multimeter but for now I put that aside as the hose is an easy test. But I have noticed 2 cables hanging behind the glovebox that ı do not know for what which I may need to figure out later :D

I will buy a new hose and try again the cruise and hope that it fixes it.


This is behind the glovebox of my Disco2 :)
F89C5774-7F05-43F2-BC9C-B7F1BE2C211E.jpg
 
Hello, ok so today I did change the hose, now the cruise seems to be holding but very weak, it is like losing it after a while and cannot hold it time to time. I could not test it fully, I may not be able to test it until the weekend after tomorrow morning but lets see there is still hope.

But if we assume that it cannot hold the speed what could be the next solution to try? Would it be the pump?
 
keremctnr said:
Hello, ok so today I did change the hose, now the cruise seems to be holding but very weak, it is like losing it after a while and cannot hold it time to time. I could not test it fully, I may not be able to test it until the weekend after tomorrow morning but lets see there is still hope.

But if we assume that it cannot hold the speed what could be the next solution to try? Would it be the pump?
Click to expand...
I had an intermittent CC and it turned be an iffy master switch contacts, the system dropped out than returned or pressing the master switch off-on a few times reconnect it, but that was till the next time, dirty contact I suspected, so switch replacement time as my switch couldn’t be dismantled sensibly.🙁

Iffy vac pipe to the diaphragm and also onwards to the brake pedal via a T piece, so hopefully you replaced the lot.
If, its possible to do a static function test, then you’ll need to know how the ECU functions first, but I suppose power supplied directly to the vac pump will get it running.
I take it that the D2 doesn’t have a factory diagnostic facility for CC 🙁
 
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