Xantia stuck in hard mode

[Hell Razor5543]

I would also use an acceptable digital multimeter, as it will have polarity protection.

[xantos]

At last! I have managed to locate the source of the problem... It was a broken contact under the engine fusebox which suffered galvanic corrosion (Al-Cu), so it was not the relay fault, but the alignment of planets
Thank you for all the help!

So back to stuck in hard mode. I was thinking that maybe there is another corroded contact somewhere so I don't get power to the electrovalves.
Worth trying bringing a new cable to the hydractive computer (the cable with diodes soldered on)?

[xantos]

I have finally done it!

Figured that the hydractive ECU doesn't get power so connected a new cable and the electrovalves came straight on!

But it wouldn't be a Xantia without any further problems. Now the diodes (that I soldered to the cables some time ago) get very very hot. So hot it burns your fingers if you hold it sometime... Any ideas? Maybe putting in 3A diodes would help? At the time I have 1A.

[Mandrake]

The diodes shouldn't get hot. I only have 1 amp 1N4008 on mine and they are cold to touch.

Either the diodes are faulty or they are connected back to front! The cathode (white band) should go to the electrovalve control line, while the anode should go to earth.

The electrovalves are positive side switched unlike many solenoids in cars that are ground side switched, and the diode is connected as a reverse EMF clamping diode across the electrovalve.

Edit: correction, 1N4007 which is a rectifier diode, not 1N4008, which is a low power signal diode and not suitable!

[xantos]

This is what I've done:
http://tinypic.com/view.php?pic=333jo68&s=5" onclick="window.open(this.href);return false;

Looks right, right?

Cut the two green wires and connected them directly onto the battery, with a 5A fuse in between. Now I can hear the electrovalves buzzing and the car suspension has transformed drastically. You can hear the electrovalves buzzing even with the white connector (the one with diodes) not connected to the ECU, but diodes are getting hot.

The diodes are very hot even when I turn the ignition off (constant +), so I've disconnected everything.


But it wouldn't be a Xantia if there was nothing else going wrong

[Mandrake]

I don't understand, is the striped green wire you show all three diodes going to earth or is it 12v ? It should be earth but in your picture you indicate battery plus ???

If it really is battery plus you should disconnect it immediately or you risk burning out the electrovalves.

If the common anode of the diodes were connected to battery plus all three electrovalves would be energised all the time, the diodes would get extremely hot and the electrovalves will be damaged as they cannot take full 12v for long periods of time without overheating and burning out. The output transistors in the ECU could be damaged by it as well.

You need to be really sure you have things connected in the right place. I would start by removing the diodes and testing the suspension operation without them until you're sure what goes where and that all the wiring is correct.

[xantos]

Yes it's battery plus...

I figured that out from the hydractive wiring diagram. It suggests that from battery through fuse 5A and then it splits into 2 wires which go to pin 1 and 2 on the ECU. So when I measured pin 1 and 2 I got no voltage (from pin to battery (-) or to earth). I got voltage though from pin to battery (+). So when measuring fuse F8 (5A) I got voltage on one pin (fuse was out) to battery (-) and when measuring from diodes (soldered part on the cable) to battery (-) no voltage. Thought that there might be a broken cable/connection somewhere and decided to install a new cable. Really getting frustrated here...

Didi I burn the valves? They were connected to 12V for about 4 hours. That would really be a bonus...

If the diodes in the electrovalves were ok and when putting the diodes on the cables there should have been the same effect (soft car)?
I think there might be problem in the hydractive ECU although I soldered the "cold" solders on the circuit board...

[xantos]

http://tinypic.com/view.php?pic=97o3me&s=5" onclick="window.open(this.href);return false;

[xantos]

Didn't burn the electrovalves, they are still humming when connected to 12V. Figured that 12V goes to pin 1 and 2 on the green connector on the hydractive ECU. And there is voltage.

So I am 99% sure that there is a problem with the ECU. Is there a way to check the VN05N's?

[CitroJim]

So I am 99% sure that there is a problem with the ECU. Is there a way to check the VN05N's?

Yes, with a oscilloscope. You should see an initial half second of 12v followed by a near 50:50 square wave for however long the electrovalves are held activated..

The 'scope display will look like this on a good ones:



You also need to get the ECU on a Lexia or ELIT to check for any stored faults and correct operation of the sensors feeding data to it.

If you can hear the electrovalves humming then the VN05s are basically functional.

[Mandrake]

That's a bit of a beast of a scope you've got there to be using on a car Jim...

You could do with something smaller and battery powered, like this:



or even smaller again:

[CitroJim]

That 'beast' was used purely for photography Simon....

For everyday automotive use I too have a little battery operated 'scope..

One of these little babies...



It's almost vintage now but still does a great job...

Here it is with another piece of vintage test kit, something I'd be lost without, and just creeping into the picture is yet another piece of very valuable test kit for a hydraulic Citroen...

[Mandrake]

That 'beast' was used purely for photography Simon....

For everyday automotive use I too have a little battery operated 'scope..

One of these little babies...



It's almost vintage now but still does a great job...

Ah, I remember those I never owned one but wanted one back in the day but couldn't afford it...

Mine if you don't recognise it is very much vintage as well. An NLS Miniscope MS-215 dating to 1978 Dual trace 15Mhz, a great little unit. Me and Dad both picked one up for next to nothing around 10-15 years ago, replaced the batteries and fixed a couple of minor faults in his one and have had them ever since. Lets see if todays portable digital scopes are still working (or easily repairable) 35 years from now!

I had to dispose of my bench scope when I moved from NZ so I was glad to have the little portable one that I could bring in a suitcase, it has done sterling duty helping me fix the car as well as a stereo amplifier and a couple of other things in the last few years...

Here it is with another piece of vintage test kit, something I'd be lost without, and just creeping into the picture is yet another piece of very valuable test kit for a hydraulic Citroen...

I don't recognise the one in the foreground, is it an ELIT ? It looks a bit like one but seems older than I'd imagine...

[CitroJim]

Yes, that's an ELIT Simon...

It does almost all a Lexia does right up to Xantias before the HDi came along and then all it can't do on them is the engine..

Great thing is that it's self-powered from the diagnostic socket and boots up instantaneous. There's no mucking around with laptops and it also is not interested in RP numbers or VINS. It's real plug and play and very quick for basic diagnosis..

It won't do keys though....

I have another couple of 'scopes in the attic store.. That Hameg you saw above and an old Telequipment one that's getting on for 40 years old if it's a day. I repaired it and it's still good..

All my little Thandar has ever needed was a new set of rechargeable batteries..

[xantos]

So the VN05N's are purely for kicking the electrovalves in and making them oscillate as I understand.

Since connecting the elctrovalves to 12V (not connected anymore) I can hear sometimes when stopping the car and closing the drivers door a few clicks from the electrovalves and a bit of humming but then everything stops (2-4 clicks in half a minute and buzzing between). Is there a possibility that some errors have logged in the ECU making it not function as it should?

The ride is harsh so the electrovalves are not functioning properly when driving. I know since it was a really soft drive when they were connected to 12V. What is puzzling me that they were not working at all, but since they were connected to 12V they are "trying" to function...