After 2 years with my cruise not working, following work done on the car by local Citroen independant garage to rectify overheating problem, overheat problem solved but cruise would not work!! Garage spent sometime trying to trace the problem without success, then 2 years later after reading posts in this forum I thought what if I tried the piece of fuse wire between terminals 9 and 10 and see what happens trick.... Hey presto cruise now working!!
However there are some differences with the way it works now and the way it used to work! Life is never that simple is it!!
The problems are these:- When cruise is selected at say 70 mph if I want to reduce speed down to say 65mph if I try using the stalk pushing down to reduce speed when I get it down to 65 and let go of the stalk it shoots straight back up to 70 again. It didn't use to do that it would have continued at 65 mph as the new selected speed, whats happening?
Also I have noticed that when the selected speed is cancelled by pulling the stalk towards oneself it is cancelled but on reselcting cruise again it goes straight back to the previous speed. Is this normal? Finally by using this bridging trick across 9 and 10 what function is being replaced? Presumably a relay that has ceased working is being replaced by the fuse wire! Am I right in thinking this? If so which relay is it and where is it located?
Should add car is 1993 crossplatform Mk 1 2 litre petrol turbo auto. Has hydractive 11 suspension and RP number 6065. This is my first posting on this form!

Hi XMERV

Welcome to the forum. Seems you have one of the regular problems that a good few choose just to live with. I find cruise a very valuable function on the XM particularly when fully exploited on an automatic. Unfortunately on a manual gear changing dissables cruise operating needing a reset. These days with only 2.5TD's my cruise installations are fully electronic and so much simpler than that fitted to your car. I will have a look through the wiring diagrams and see what I think bridging 9 to 10 does or cuts out then edit some extra on the end of this post.

On the Cruise Control Control Unit (Iten 60 cruise ECU) pins 9 & 10 are both positive 12 volt feeds from the ignition switch via Fuse F2 of the main fuse board in the passenger side dash. The feed then splits.

The feed to Pin 10 goes to the Cruise Control Dash Switch (Item 611). When this switch is on there should be a direct feed to Pin 10 on the ECU. There is also two feeds from this switch to different contacts of the Cruise control selector switch (Item 214).

The feed to Pin 9 of the ECU goes from Fuse F2 to an extra normally closed contact on the back of the Stop Lamp Switch (Item 319) located in the Brake pedal. Citroen supply two versions of this brake switch (with and without the extra contact) and it is not unknown for the without version to be fitted in error to a car with cruise. Even with the correct switch the cruise contacts can suffer oxidation breaking what should normally be a closed circuit. From the brake switch the feed to Pin 9 goes via a normally closed switch or relay (Clutch switch Item 328 on a Manual car and Cruise control relay Item 831 on an Automatic car).

John

Thanks for that info, will now try and locate item 831 relay, any ideas where this is mounted?
The brake pedal switch was replaced 2 years ago in an effort to resolve the problem, it could be that the wrong version of the pedal switch was fitted, I will check. Thanks for your help.
Regards Merv.

Hi Merv

According to the circuit diagram the feed wire from the cruise relay goes direct to Pin 9 of the Cruise ECU and is geen in colour. There are no connectors or other wire joints in its length so the relay is likely to be in the engine bay close to the ECU. There is just a chance that you might be able to follow the wiring if it is not all bound up into a loom. I seem to recall that I have recovered one of these looms for CitroenXM a while ago so he might be able to trace and position bits for you. No doubt he will comment when he sees this as he is trying to retro fit XM's with Vac Cruise. The Brake pedal switch is easiest checked at the plug & socket joint clipped to the metal arm. If there are only two wires instead of three on the switch side then a simple brake light only switch has been fitted in error.

John

Hi John,
Thanks for that info will have a look around the area where ecu is fitted . There are several relays mounted on front panel on drivers side seem to remember they are mounted on a piece of metal that is razor sharp!!
Regards Merv.

Hi Merv

I would expect not expect it to be one of those on the back of the fan panel behind the headlight as there is a plug connection in the wiring for that. Try the front of the ECU box first.

John

Hi Merv, found this for mk1.

Oops! try again!

Looks like site not happy with TIF files,nonetheless it shows relay 831 in area adjacent r/h headlamp,and 801 adjacent l/h h/lamp.Just genaral location.

Hi again Merv, have scanned it for upload, so you should be able to see it.

Hi John and Hi Robert !
I am amazed at the level of support this club is giving its members absolutely fantastic...long may it continue!Thanks guys!
The diagram will certainly help in identifying the various bits a big thankyou for that!
Have not been able to get my head under the bonnet as yet due to family committments and am driving the car from Cornwall to Ross-on-Wye tomorrow, so heaven knows when I can get stuck in under the bonnet.
One interesting discovery I have made today, I rang the local Citroen Dealership in Plymouth to ask if cruise control stalks for Mk 1 XM 's were still available and if so at what cost.....yes they are sir special order and £42 plus VAT came the reply! That was a bit of a shock I seem to remember reading somewhere that they were about £27 or so !
Thanks again guys, will let you know when there is more to report.
Regards Merv.

I agree with Jan, the switch is just 3 pairs of simple contacts and easy to test for correct operation.

John

the brake pedal (the bit your foot touches comes apart and is cleanable) mine went and that cured it....i believe this is a very common fault and is nearly always down to this component. as for the stalk.....pull it towards you and it has same action as touching the brake pedal.....nock it down and you slow down when you reach desired speed nock it down twice in quick sucsesion and that speed is held. the same aplies to speeding up lift and hold you pick up speed...tap up twice and you hold speed. mines an auto and the cruise is a godsend. specialy for speed limits.. comes in handy there.

My cruise control is now fully sorted! The two things that I had to do to get it all working were a piece of fuse wire between terminals 9 and 10 on the cruise ecu, and I replaced the stalk control which was faulty. The bad news was the cost of the stalk a hefty £47.69 !! It's nice to have it performing as it should do.
Regards Merv.