Xantia cruise control repair

[CitroJim]

Yes as the cruise ECU was updated near the end of Xantia and XM production.

The early ones (long ally box) and the late ones (short ally box) are NOT interchangeable.

Late Xantias moved the cruise ECU to the end of the centre consle (next to the handbrake) from the driver’s side B pillar under the carpet.

[Mandrake]

Speaking as someone who fearlessly tears things apart, the stalk is pretty much a sealed unit. :/

That's what I was afraid of.

The occasional double/triple click of the relay when moving upwards did not happen when I first got the car as I remember testing the stalk and relay operation back then, so it seems that the switch has oxidised in the year and a half of non use since I've had the car. When I was beep testing the switch contacts a couple of weeks ago all three were very intermittent, after a bit of working the stalk in every direction the normally open up and down ones are now fine but the pull forwards normally closed one is still slightly intermittent and sometimes goes momentarily open when moving the stalk up or down. (usually up)

I did try to spray it with some LPS 1 which in my experience can work miracles if you can get it inside the switch... but I can only just get the spray nozzle past the rubber boot on the top side of the stalk and I have no idea whether the nozzle was aimed at the switch body, so I very likely missed it altogether and just gave the inside of the steering cowling a dose.

If there is even the tiniest hole or gap in the switch moulding that stuff will penetrate in and most likely fix it. Would dropping the lower steering cowling down make the switch body visible so I can directly spray it ?

[Mandrake]

As far as I remember a quick flick up will resume to the previously set speed, a flick down will set the current speed, holding up will accelerate until released and holding down will decelerate until released then maintain the speed at the point of release. A pull towards you will cancel the cruise action.

It's hard to be certain, but I think that's what its trying to do - a flick down to activate cruise at the current speed and a flick up to resume the previous cruise speed. I think what's happening is that when the cancel switch contact bounces the multiple activation confuses it and causes the memorised speed to be reset to the current speed.

I often used my cruise control in a 30 limit and didn't experience any jerkiness, it was always smooth at any speed, in fact it was better than the fully electronic control in the C5 in its ability to hold a constant speed.

Well once it settles down its relatively smooth at maintaining the speed, but engaging or adjusting the speed with the stalk at low speeds is quite lurchy.

Just pressing it upwards to increase the speed slightly causes quite a big surge of acceleration complete with the back suspension squatting It just seems that when it increases or decreases the throttle it moves it quite quickly.

Perhaps what I should do at low speeds is adjust the speed myself with the throttle or brake to the desired speed and then flick the stalk downwards to activate and lock at that speed, rather than trying to make a speed adjustment with the stalk ?

[Mandrake]

Yes as the cruise ECU was updated near the end of Xantia and XM production.

The early ones (long ally box) and the late ones (short ally box) are NOT interchangeable.

Late Xantias moved the cruise ECU to the end of the centre consle (next to the handbrake) from the driver’s side B pillar under the carpet.

That's interesting Jim, it appears once again my car is a cross breed! Despite being an early 1998 and having the cruise relay under the front wheel arch like an early car, my cruise control ECU is inside the end of the centre console below the knick knack tray, (behind the hand brake) and is an alloy box about 100mm (?) long. Does this mean I have the "late" model ECU with the later behaviour ?

[CitroJim]

That's an early ECU by the sounds of it Simon.. The later ones are a bit more squat..

Let me know the Hella part number and I'll confirm for sure..

[addo]

The shroud is not hard to pull down if you're confident. The stalk is secured with three Torx headed screws; can't remember if they're T15 or T20.

Mine's occasionally non functional but it seems the brake switch is the culprit.

[Mandrake]

I'll have a look at the part number at some point Jim - I may have exaggerated the length of the ECU, that was only a guess! It's not very long.

Addo: torx for the switch, but what holds the steering cowling in ? I really need to get myself some more torx screw drivers. I have a full set of bits in my removable set but the stalk of that is far too fat and short for some removal jobs, I only have one stand alone thin stalk torx driver and from memory I think its a T15, so I need to get myself a few other sizes around that size.

What are the commonly used sizes on Citroen's ?

[Mandrake]

Must try that this morning on the way to work..

You're working on Sunday ?

[addo]

I've worked all weekend.

[addo]

I swear by one of these:

http://www.ebay.com/itm/190855109625" onclick="window.open(this.href);return false;

A Snap-On ratcheting screwdriver with the female hex end. What it doesn't get, I have a small bit holder and right angle adaptor to attack. T20 is the most common size for PSA fasteners, with a few T30 (internal door latches, armrests) and just a handful of T10 (door window switch panels), a small number of T15 (from memory, bottom inside of aux power socket) and T40 is the big gun for seat rails. With the seats, I prefer to use a wobble extension and 3/8" drive. The shroud comes off easily with this driver and a T20 bit.

[CitroJim]

T20 ..... will manage most jobs around the cabin including steering cowl if memory serves ...

Yep, except T30 for the airbag bolts and T10 for the small screws in the centre air vents.

Must try that this morning on the way to work..

You're working on Sunday ?

Sadly yes, finished now. I have to occasionally when jobs need to be done outside normal hours. I benefit by having time off next week...

[Mandrake]

As far as I remember a quick flick up will resume to the previously set speed, a flick down will set the current speed, holding up will accelerate until released and holding down will decelerate until released then maintain the speed at the point of release. A pull towards you will cancel the cruise action.

Looks like you're right on both points, I was trying it out a bit more today - flicking it up to resume cruise does indeed return to the previously memorised speed, although depending on how much speed it needs to make up it can take a while to get there.

Even though the diaphragm is physically capable of fully opening the throttle it seems to be fairly conservative on opening the throttle and will only open it wide gradually to maintain speed up a hill, it won't open it wide to achieve rapid acceleration. I'm guessing that it considers both the road speed and the acceleration and won't open the throttle at a rate that would exceed a predetermined acceleration. (After all it is "cruise" control not launch control )

Flicking it down does indeed reset the cruise to the current road speed - both when resuming cruise and even if the cruise was already active and the preset speed was above or below the current speed.

This is handy if you go from say a 30mph to 60mph zone, when you enter the 60mph zone simply accelerate as normal with the pedal, when you get to 60 a brief downwards flick will memorise the new speed and smoothly take over. or vica versa slowing down, just brake to reach the new slower speed limit then flick the stalk down after releasing the brake to hold there.

I often used my cruise control in a 30 limit and didn't experience any jerkiness, it was always smooth at any speed, in fact it was better than the fully electronic control in the C5 in its ability to hold a constant speed.

I think I've got the hang of it now - at slow speeds in low gears lifting the stalk to accelerate causes an ungainly surge in acceleration (and overrun lurch when you let go) so rather than that I just make a correction in speed normally with the throttle or accelerator (for example from 30 to 40 or back) and then flick the stalk down to memorise the new speed, that way it smoothly takes over with no lurching.

I like it It's a shame everyone around me keeps speeding up and slowing down to ruin my fun.

[CitroJim]

Now you can play the game of trying to say on cruise for the longest possible time Simon. You'd be amazed how with practice you can even in quite dense and variable traffic.

Early mornings are best. I once went to the Northern Rally. I engaged cruise as I joined the motorway at Newport Pagnell and disengaged it on the slip road on the Wetherby junction... That was between about 6 and 8am on a Sunday...

Cruise takes a little practice.

You know I've learned something today about flicking the stalk down. never knew that. Excellent!

Yes, the resume acceleration is very tranquil and gentle...

[Mandrake]

Drat! Cruise stopped working today for a while, then started working again later. From the double relay click when trying to activate it (instead of a single click as it should be) I can tell that either the brake switch is playing up or the normally closed pull towards you contact of the stalk.

Its hard to be certain but I think its the brake pedal switch, which I already sanded with emery paper, and from memory it has plenty of contact tension too.

What's the next step for a particularly stubborn brake pedal switch ?

[Stempy]

A new one worked for me....