My mechanic is a bit stumped by my cruise control problem...

[cdrtravis]

Hi

I know that cruise control problems have been addressed elsewhere on this forum and I have done a search. Alas, the information I have found has not helped my mechanic.

Last week, on the way home, the cruise control worked intermittently. Sometimes it would engage and other times it would not. When it did work, it held the speed perfectly.

The next day, the cruise control would not work at all. I inspected the hoses, especially around the T-piece and all was good. I tested the actuator for vacuum and that also was fine. I then opened up the vacuum pump and it is clean inside. The horn works, so the rotary coupler must be alright. The fuse is still intact. I was going to inspect the pedal switches, but decided that looked too hard, so off to the mechanic I went.

He reckons the switches are fine, but doesn't know how to test the vacuum pump. He doesn't know if it should run constantly when the cruise is on, or as required. As far he can determine, no power is going to the pump. He's really not sure how to proceed and doesn't want to fumble about blind and charge me for the time.

Hope an expert can come forward! Vehicle is a '97 V8 Disco.

Cheers.

[4bee]

Cruise has been fine with 2 exceptions.


1. Rotary Coupler was buggered. Replaced. Fixed.

2. Steering wheel switch was intermittent. RH one I think it was.
Carefully opened it up in situ & found some tiny bits of silver foil that were floating around in there & holding it open. Cleaned & has been ok.



Pedal switches (1 or 2) may be out of adjustment a bit & breaking the vacuum. There is also a T piece down there as well.
The WM shows them as an adjustable screw type but mine clip in & the adj. is fixed. The electrical plug (s) could want reseating as they only latch on.

There was an excellent post done by some knowledgeable person on the CC & some of us suggested it go into Tech Section but I don't think it made it into there. Pity.

[cdrtravis]

Yes, from what I understand my pedal switches are non-adjustable as well. I hadn't considered the switch on the steering wheel. If I remember correctly, when it was working intermittently, I was able to use the Resume button, but not the one for setting the speed. Hmmm...

[LandyAndy]

Dont you NT blokes just hold them flat out:D:D:D:D:D
I guess not since they recently gave you a max speed.:p:p:p:p:p:p
Andrew

[4bee]

It's probably the same construction as 'RESUME' so it would be possible for similar flakes to come adrift.

It does come apart using a very fine screwdriver to lever (?) the lid off & some good tweezers to remove the bits. If you go in, just take your time as the components are obviously tiny.

No idea what a new switch is worth.

[GrahamH]

Hi 4bee, I think you might be referring to a thread on the cruise control which is located at http://www.aulro.com/afvb/showthread.php't=34133&highlight=cruise+control.

To be honest, I'm not sure that my info there adds anything to remedying the problem cdrtravis has, but it is worth bearing in mind that the vacuum operated cruise control is very, very slow to operate and is not particularly impressive in its operation - OK on the flat but not great at holding speed on hills. It might just be that you're expecting it to pick up the speed more quickly than it is able - it takes about 30sec to set itself.

I checked out a fair bit of mine to find out why it wasn't operating and it all came back to the hoses around the brake and clutch pedal having fallen apart. I'm sorry I can't tell you if the pump operates continuously but my strong suspicion is that it doesn't - I believe the control relies on the system holding vacuum and if you have any leaks, it doesn't work.

Interestingly mine has stopped operating again and I haven't been playing around above the pedals as I had last time. If I can find the cause I'll post here again.

I have been seriously considering a fly by wire aftermarket cruise control to replace the LR vacuum one - we have one in my wife's Corolla and it works brilliantly. Interestingly it achieves the connection from the steering wheel controls to the controller with an RF link - there's a battery in the switch box on the steering wheel which requires periodic replacement.

[camel_landy]

Couple of pointers...

1 - Vacuum - If you take the hose off the pump & suck on it, does everything move as it should? If it doesn't replace the hose. (Remember to use the correct hose as normal stuff will collapse under -ve pressure.)

2 - Peddle switch - I had problems with alignment on one of my cars... I found that a small self tapping screw, into the end of the switch, worked a treat. ;)

HTH

M

[4bee]

Hi 4bee, I think you might be referring to a thread on the cruise control which is located at http://www.aulro.com/afvb/showthread...cruise+control (http://www.aulro.com/afvb/showthread.php't=34133&highlight=cruise+control).


Thanks Graham, that was the one.:D It may not fix cdrtravis's problem but I thought it went a long way to explaining the "black art" of the LR CC.

******** Maybe now, a Moderator may include it in Tutorials please?

cam_landy. I meant to add the suck the hose & see bit, & that is a good initial test.

I also don't know for sure whether the vaccy pump runs all the time but I was under the impression it did, from somewhere.:confused::confused::confused::confused: :confused:

One way to "test" it I suppose, is to hook up a 12v lamp to the pump socket feed at the pump & go for a drive above 40 kph.

If the VSS was not operating correctly, then the speedo wouldn't, in theory.

[davros]

The pedal switch is adjustable but tends to adjust itself. It is easy to remove, pull off the plug and twist it - it's a bayonet. Grasp the actuator and pull it outwards and it will move out click click click. Put it back in place whilst holding the pedal down then slowly release the pedal so it self adjusts.
The problem that may occur is that the play in the pedal allows the pedal to bounce "up" and press the actuator in too far. (the switch actuates when "released). Then when the pedal moves back down the switch is so sensitive it flicks the brake lights over bumps causing the cruise to de-activate.
I had to fill my switch with 5min araldite and let it set after adjusting before driving the car - all good now!

Dave

[adnic]

my 95 v8 disco had a few moments like this on a recent big outback trip. if travelling for long time on CC it would drop out. leave it for a few K's to cool & it would go again for ages before cutting out again. i haven't done the fix yet but i would be betting it's heat related to the pump or a dry joint in the wiring nearby. hope this helps.
adam

[cdrtravis]

Well, I've spoken to my mechanic about the switches on the steering wheel and he told me that when he presses Resume he can hear a relay click, but when he presses Set, there is nothing. I suggested to him he open up the switch and take a look.

We'll see what happens. Thanks to everyone for their help so far.

[4bee]

Silly question time.:D

I suppose he is doing this while driving on the road over 40kph, not in the workshop?

[cdrtravis]

I hope so! I suppose I'll find out when I give him a call this afternoon.

[BigJon]

The horn works, so the rotary coupler must be alright.

That is not a good assumption. There are plenty of wires in there, maybe only one or two are broken.

[ladas]

That is not a good assumption. There are plenty of wires in there, maybe only one or two are broken.

Yes that is correct - I had the SRS fault - and I did a bodgy repair - then later the cruise stopped working - and I inspected the coiled up ribbon cable in the coupler under strong light and there was a break - and two more were hanging on.

I replaced the rotary coupler and everything was fine.

It is fairly easy to test the coupler - remove it and just check the resistance for each wire.

[cdrtravis]

Steering wheel switches have been inspected and found to be wanting. Replacement module on its way.