CitroJim's Citroens

[CitroJim]

I work with Windows professionally Russ and apart from my Lexia I have no Windows machines at home at all. I'm all Linux... Make of that what you will Let's just say I'm not a fan.... I couldn't go back either. I love my Linux

A good and successful day today. feeling a bit perkier so I've been gently playing XM electricals. I've fixed my aircon I now have a blower that works properly last time I looked I saw an unvarying +5V at the blower regulator control line and assumed the climate ECU was dead. Swaps of two good ones later I realised it wasn't.. Today I paid a bit more attention to the blower regulator and noted it was an after-market job and it looked brand new. I had a spare Xantia one in stock but that didn't work either but caused the fan not to run at all! After a set of new transistors were fitted to the Xantia one all was happy and the blower works, temperatures regulate and the aircon blows cold. Excellent!

I was curious to see wht the new after-market one wouldn't work. All seemed OK and then I noted the markings on the transistors was a bit indistinct but it looked like they were MJ11016 rather than the correct MJ11015. odd.

I looked up the data on the MJ11016 and found they are the complementary NPN to the PNP MJ11015 so no wonder they wouldn't work. Gawd knows where this module came from but it was never going to work with the wrong trannies in it, that's for sure and it was how it was made as the transistors are riveted in...

EDIT: I prove they were the wrong (NPN) sort by testing them so they're definitely MJ11016!!!

I then turned my attention to the non-operational cruise control. All tests tell me the ECU is dead as the vacuum pump and dump valves work a treat, all signals and voltages are correct, including the speed signal which I tested by rigging up a battery-powered oscilloscope on the passenger seat, some very temporary wiring and going for a very short drive.

Easy I thought. I have a spare S2 Xantia cruise ECU in stock but they're just different enough not to want to play

So, I need a new ECU. Anyone got one please? The Hella part number is 5GA 004 397-17. I know a Xantia S1 one is the same as well but not the Xantia S2. How bizarre...

A good day but a bit knackered now. Next I'll see why I can't speak diagnostics to the gearbox ECU...

[russ92xmsed]

Nice result Jim fixing the air con....just in time for the blazing hot summer we won't have!!!

[CitroJim]

You never know Russ, this year might be the one. Law of averages says that at some time we are due a good one and why not this year

Forgot to say I also dropped the interior light and dusted out the cabin temperature sensor this afternoon...

The car is an awful lot nicer to be in now the ventilation is working properly

[russ92xmsed]

You never know Russ, this year might be the one. Law of averages says that at some time we are due a good one and why not this year

Forgot to say I also dropped the interior light and dusted out the cabin temperature sensor this afternoon...

The car is an awful lot nicer to be in now the ventilation is working properly

I really hope we do get a decent summer, I think we're owed it after last years effort....not to mention the disappointing spring.

That is one thing I have been impressed by after re fitting the new temp sensor, the system just gets the temp and right amount of interior breeze spot on every time.

Though the other day I did treat my self to a bit of sunroof action.

[captainhaddock]

Any ol' xantia parts Jim, just shout. You seem to be a genius, I illiterate on those yokes.

[CitroJim]

You seem to be a genius

Me? No, definitely not! You know better than that Jaap, you've met me! I'd have thought that would have firmly dispelled any doubt at all

I found an article last evening on repairing the Hella cruise control ECUs on an Audi forum of all places. Seems the 90s Audis used exactly the same system so now you can walk up to an Audi owner and say "Ha! You have a bit of an XM in your car!!" That'll please 'em I'm sure

Anyway, upshot is that the ECUs appear to suffer from dry joints on certain capacitors. I've cracked mine open and identified the joints and capacitors in question but the joints look OK so I don't hold out much hope but then again there's no harm in running a warm soldering iron over them...

I'm determined to get cruise working as it does make a heck of a difference on a long trip to be able to rest up the throttle foot from time to time...

[CitroJim]

Sadly I discovered today that my cruise issues were not down to dry joints

It was never going to be that easy

Not one to give up on these things and with a need to know what had died I looked in vain for a circuit diagram of the ECU. Couldn't find one so I drew the important bits - those that drive the vacuum pump - myself..

It turns out it has an 8-bit microprocessor to do all the magic bits but of more interest was the business end of it as I suspected that was most likely where any problems might be. I discovered in my drawing that it has a safety relay, much as in an ABS system, that supplies 12V to the vacuum pump, dump and vacuum regulator electrovalves of which the latter two, the pump and vacuum regulator, are controlled by a hefty power transistor and a much smaller pair of transistors respectively that switch on to earth the respective components and make them run. All pretty standard open-collector switching stuff really.

In testing found a short-circuit zener diode which sits across the vacuum pump motor effectively and acts as a back-emf suppressor and also found the two small transistors that drive the vacuum regulator both very faulty. The hefty transistor which controls the vacuum pump seems to be OK when tested on an AVO.

That appears the sum total of dead bits and I wonder how it happened as normally cruise ECUs are like granite - indestructible...

I can only think that someone may once have tried it on an S2 Xantia which uses a slightly different ECU in that the connections to the vacuum pump and regulator are reversed. This would mean the small transistors would try to drive the high current vacuum pump to their own detriment whereas the vacuum regulator being driven by the pump control circuit would have generated a hefty back-emf and blown up the diode...

I've ordered the bits and will try a repair. I'm not holding too much hope though but it'll be interesting to see if I can make it work again...

I've quite enjoyed my dabble into electronics today. It's been a long time since I've gone that deep into such things...

In other news I reprogrammed my immobiliser keypad so that it automatically unlocks when the car is unlocked with the plip. Bizarrely this functionality is not available in the S1 Xantia keypad it seems...

Now I must not forget the keypad code as it's needed if the car is left unlocked for a period...

[captainhaddock]

I still think it's pretty genius, glad you're up to it. I couldn't for the world go that deep.

[CitroJim]

I'm not up to anything very mechanical or anything that needs any great physical energy yet Jaap so doing a bit of electronics is pretty gentle for me and stops me going mad with boredom... And achieves something useful rather than turning into a vegetable in front of the TV

Boredom really is a big problem when recovering. I can only read books, surf the 'net or do nothing at all for so long and then the urge to do something practical and useful gets very strong...

A bit of gentle auto electrics is great for that and when that's done I go off and do a bit of cooking - something else I rather enjoy, especially baking. Something that's absorbing but low-impact and not very energy dependant.

Currently I can't bake bread as I've not got the strength or stamina to knead the dough

I've just cooked a blinding chilli con carne completely from scratch. It had a bit of a bite to it. Several tens of thousands of Scoville Units for sure. I was bit generous with the chillies

[captainhaddock]

Sounds good that chili! I think there are after market cruise controls on the market but know nothing about it. Could find out though, I wouldn't mind cruise control even though it's useless for my commute.