Cruise control not working (and it's not the pipes)

[JumboBeef]

Hello all,

Please can someone give me a bit of advice.

I only bought my Disco last week, and mighty pleased with it I am too.  I only have a couple of niggles and one of these is the cruise control.

It doesn't work, and it's not the pipes (they're OK).  The last owner, who had it for three years, said it worked when he bought the car but just stopped.  He had it checked out and was told it was 'something electronical'.

When you switch the master switch on the dashboard on, nothing happens and the little light doesn't come on.  The fuse is OK, but it is just dead.

Do you think it is the ECU?  Where is the little blighter?  I had a look under the dash in the driver footwell but I couldn't see it.  Am I looking in the right place?

Thanks in advance!  8)

[peasey]

hi, mate and welcome to the world of discovery ownership!! i have also had this problem, now the pipes were fine on mine to.my problem was that the little vac pump wire had pulled off now thats located underneath or just behind the passenger head lamp if thats not generating vaccum the the cruise wont work i think, im just going to check to make sure,yup the pump is underneath the power steering top up bottle through the hole and the tube should be attached to that.try that mate

[JumboBeef]

Thanks, but wouldn't the light on the dash still light up with this problem?

[peasey]

HMMMM forgot about that, has the bulb blown in it?other than that im at a loss ,im still learning about them myself as i have only had mine since febuary this year.sorry i cant help anymore but i reckon some of the other lads will know.

[barmiebrumie]

hi, mate and welcome to the world of discovery ownership!! i have also had this problem, now the pipes were fine on mine to.my problem was that the little vac pump wire had pulled off now thats located underneath or just behind the passenger head lamp if thats not generating vaccum the the cruise wont work i think, im just going to check to make sure,yup the pump is underneath the power steering top up bottle through the hole and the tube should be attached to that.try that mate

Will try that on swmbo's as hers don't work  but the light does come on,

Thanks John.

[Range Rover Blues]

Mine works when it feels like it so it's hard to trace the fault, but then I've got a few little electrical gremlins to sortout.

[Thrasher]

AFAIK it won't initiate if the brake switch is faulty *or* it thinks there is a rear brake light out .... worth checking the correct lamps have been fitted. I assume you've pulled the switch out (it really does just pull out) and checked the connector is snug.....

Secondly - you know that you press that switch in, and then set the cruise with the steering wheel controls .... I know some people get confused by this.

ECU isn't really part of the loop on these vehicles (I have a '97 4.6 ES)

[JumboBeef]

Thanks.

If it ever stops raining I'll have a look.

ECU isn't really part of the loop on these vehicles

Isn't this the baby?

I know about the other controls, I've had a number of motors with cruise.  The fact that the light (LED?) doesn't come on makes me think something somewhere is dead, and that makes me think it is the cruise ECU.

Where would I find that ECU unit in my car?  I want to check everything is tight and connected correctly before buying another one.

Thanks!

[Thrasher]

Ah ... that's not *the* ECU, that's a supplimentary thingy :)

It will usually be behind either the passenger or driver kick panel....or if you are really unlucky - in the spaghetti under the steering column :(

Mines only ever failed at the stage of split pipes. As ECU's have no moving parts I'd go for either a dry joint (would give intermittent operation) or simply a connector coming adrift (LR cable tie some together.....unreal)

[JumboBeef]

Well, I tried to have a look but the rain beat me after five minutes.

I pulled the switch out and all *seems* OK there.  When I switch it in and out, I can hear a relay clicking, under the passenger seat (I think).

[andrew2986]

Hi,
I had a  real nightmare geting my cruise to work, once all the pipes are good including the one that goes into the car and down to the switch above the brakelight switch on the brake peddle, i worked out that the cruise switch on the peddle needed extending as the even when seated correctly the switch plunger wouldnt touch the peddle, put a small self tapper in the end of it and bingo,! all ok now.

Andy

[The Electrician]

brougt a 95/96 ES and the button lights up.....get to 60 press 'set' on the steering wheel and......nothing !!!!

so, i'll check all the pipes and pedel plunger thinggy;s and whatever, but does anyone know how they work.

Gary. :roll:

[Guyh2]

but does anyone know how they work.

Which bit, I've spent quite a bit of time working through my CC to get it all working again.
Basically there's an ECU controlling a vacuum pump and a valve. it runs the pump to accelerate opens the valve to decelerate. The vacuum pulls in the diaphram on the actuator which pulls a rod which operates the accelerator. Electric switches on brake, clutch or autobox and vacuum release valve on brake pedal.

Actually reasonably straightforward, just lots of bits to check. I have got a troubleshooting guide around somewhere.

to check the 'plumbing' Try grabbing the end of the actuator, it should only move slowly and the only sound of air escaping should be on the n/s behind the headlight under the jack. (you may not even hear it)
If ok then it's electrical fault finding time

If you get stuck, give us a shout, I'm only in Coulsdon/Oxted

Cheers
Guy

[The Electrician]

Thanks Guy, I will give that a go, and you my get taken up on your offer of help, I drive from Beckenham to Gatwick via Croydon, everyday, so almost right past you.

I stripped my last Discovery down to spare parts after destroying the gearbox and transfer box up at langdale quest in north Yorkshire.
So i know my way round a Discovery, but never had a posh one with Cruise Control or auto box for that matter.

anyhow thanks again mate.
GARY. :D

[JumboBeef]

To answer the original post of this thread (which I started), I have found out what was wrong.

The connector had come off the brake pedal switch.  That was all, and now it works perfectly.

The old owner lived without it for three years! and sold it without saying it had cruise because it didn't work.

Chuffed, me  :D

Thanks for all your help.