Broken Cruise Control

[mjb]

The cruise control on my v6 is broken. The previous owner thought it was the stalk but after a bit of driving I can hear a relay clicking from behind the glovebox when I try to activate it at speed so it's evidently not the gear sensor, speed sensor or stalk at fault.

Any suggestions as to what could be wrong?
Where's the relay and electronic gubbins for it? (what side of the blower is it, what does it look like, how many plugs, etc)
Is there any way of fooling it into say holding a high idle for testing purposes?
Whereabouts is the solenoid near the throttle, and how do you get to the throttle on this thing?

[steve_earwig]

Is there any way of fooling it into say holding a high idle for testing purposes?

One way springs to mind, raise the front of your car in the air. I once put a 5 speed box in a Craptina and though I'd better make sure it all worked before I tried to drive it, it was indicating 110mph and I was wondering how far it would go through the house opposite if something happened to the stands.

[steve_earwig]

Just had a sniff about, I can't find much and Haynes is typically useless - the ecu's behind the glovebox and the other gubbins is under the bonnet (no sh1t!). One thing occured to me, try the coupe club. I'm in their forum now, the first thing is to check the fuses (well duh!), then the brake and clutch switches can give trouble. If you've not aready, it might be an idea to join ('cos seems you have to join to read the forums).

That thread I was reading.

A brief search later.

[mjb]

the other gubbins is under the bonnet

I've had a look and figured all that out. It's just a vacuum cylinder attached to the round bit on the throttle body (the throttle pedal cable goes to the round bit directlt). The vacuum hose goes down and back, so it looks like it enters the bottom of the footwell somewhere. However I've had a look under there and can't see anything with a hose attached. There is however an extra box under there that the tubby didn't have.

One way springs to mind, raise the front of your car in the air.

I've thought about that and REALLY don't like the idea. The power of this engine would be enough to do some Seriously Bad Things(tm) if it dropped in gear with some revs on! Wonder if I could have a chat with the guy in National Tyres and get the car up on the centre lift. Guess the only thing I could do up there though would be to check the vacuum hose to the actuator

To be honest the rod linking the actuator to the throttle is very loose. Wondering if the actuator's toast...

the first thing is to check the fuses (well duh!)

I'm an idiot. Guess what I haven't done? I'll be back in a few minutes...

then the brake and clutch switches can give trouble

Good thinking. If I can find the ECU and pin-out I'll give them a check

[steve_earwig]

Just a thought - just disconnect the switches. Or short them. Or whatever. At least it'd eliminate them.

[mjb]

Again, I prove what an idiot I am. I go out in the freezing cold, kneeling in the middle of the road, open up the fusebox... and THEN look at the Haynes, which says it's the same fuse as the windscreen wiper and heated windscreen - both of which definitely work. GAH!

Nevertheless I checked all the fuses (noting a wire attached to the cigar light's permanent feed line - is there ANY 406 that hasn't been fitted with a car kit? ) and they're all ok, as are the engine bay ones.

The fuse is a 30A one though, so I should be able to fit my multimeter in-line fuse probe in and see if it pulls any current (the vacuum pump) when activated.

[mjb]

Actually... Haynes says "Slide out the hinge pins and remove the glovebox from the fascia. Undo the retaining screw(s) and remove the access cover from the fascia to reveal the ECU"

I never saw anything like that on the 2 tubbies!

[DaiRees]

One way springs to mind, raise the front of your car in the air. I once put a 5 speed box in a Craptina and though I'd better make sure it all worked before I tried to drive it, it was indicating 110mph and I was wondering how far it would go through the house opposite if something happened to the stands.

I don't reckon it would, there are 2 possibilites. 1, It'll just stall on contact with the ground, 2, If you're giving it the gas then it might have enough power to prevent the stall, instead the tyres would spin (at 110 mph) and you'd start to move forward relatively slowly in a cloud of smoke a-la burnout, then you take your foot off the loud pedal, apply the brakes and come to a stop within a couple of feet.

If however the driving wheels were up in the air and the throttle were jammed open (with, for exampe, a hammer like I did on my jeep once while trying to pinpoint a transmission noise ) but you weren't in the car, then you might be lucky enough to witness that burnout and the ensuing spectacle of carnage as nothing more than a mere bystander

[mjb]

There's a switch under the clutch pedal (accessible) and 2 under the brake (barely accessible). On the brake, the one to the NS is the brake light and the one to the OS is the the cruise control switch.

These switches... I can't work out how they're supposed to be held in! They're practically loose! I managed to knock the brake switch out, and went for a 5 mile test drive with my sodding brake lights on!!! I only realised when I decided to do a lights test once I'd parked up at home...

EDIT: Checked servicebox and it looks like the white plastic collars are what should be holding these switches in place. What about the other side of the mounting plate?

[mjb]

OK it evidently IS the switches... I had it on this morning!!! Strange feeling of the accelerator pedal going down on its own, but it worked!!! Didn't work again though :/

I'm not sure if I had brake lights either - I couldn't find anywhere to test them

[steve_earwig]

OK it evidently IS the switches... I had it on this morning!!!

Yay!!!

Strange feeling of the accelerator pedal going down on its own

You get used to it. Just try not to fall asleep...

but it worked!!!

Woohoo!!!

Didn't work again though :/

Boo hisss At least you know where to look now.

I'm not sure if I had brake lights either - I couldn't find anywhere to test them

No convienient walls for you to back up to? You do live in a strange world!

Dai, you missed out the third option: something going BANG! It all worked ok though, I just had to modify the exhaust rather a lot. Then a month later some bastard nicked it , I never saw it, or any of the mods I did to it, again

[Welly]

So the cruise control thought you had your foot on the brake/clutch preventing it from working I suppose the clips that hold the switches are typically 'french' eh?

[steve_earwig]

Long since surrendered?

[Welly]

Actually I meant blue and white stripy, perhaps a bit - err, 'grubby'

Remember at school when the french exchange students used to come over for a couple of weeks. That was my first experience of hairy armpitted girls, there was something kinda eau natural about those people

Come to think about it we've not got one single french member (biggest 406 population) to my knowledge and yet we have members from Indonesia, Auz, and even Wales!

carry on.........

[teamster1975]

That was my first experience of hairy armpitted girls

I hope it was the last too Welly!
Reminds me of a mate of mine at college, real old hippy. His wife didn't shave her legs in the winter for whatever reason I'm shuddering at the thought now!