Help !! Intermittent tacho and diesel clatter

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Tebster
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Post by Tebster »

Could a fault with the instrument cluster cause all these problems with so many circuits ?
The reason why I ask is because shortly after buying this car I changed the bulbs in the cluster, and from then on the brake pad wear light came on and off / flickered, when the cooling fans went into hyper drive the pad wear light would go off but when the light was on the cooling fans were off.
This is strange because there are no wires attached to the pads either and therefore the light shouldnt illuminate anyway.
Recently I got so fed up with the pad wear light that I removed the bulb and since then things have just got more weird.
This car is like that one on a video called christine, only this one dont like its owner...lol
Tebster
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Post by Tebster »

Another funny thing is that when it rains these faults seem to get worse, does anyone know if the refrigerant temp sensor is connected to the condenser ??
Dave Burns
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Post by Dave Burns »

There is something on the drier bottle, but it looks like a pressure switch to me.
If by refrigerant temp sensor you are refering to component 8008 in the BOL, then why would the BOL be refering to it in the cooling system diagram, they usualy ignore any component of the aircon unles its integrated with the cooling system such as the bitron sensor and controler.
Me thinks there could be a cockup here and item N0.8008 might actualy be an engine coolant sensor, since this is the cooling system wiring diagram and this is the only temperature sensing component drawn or mentioned, so thats seems a bit odd to me.
Anyway clock the wire numbers and see if you can match them up to those going to any of the sensors on the stat housing.
Component 8010 I think is the Bitron controler, it is shown as having a 15 pin connector, check the wire numbers to see if they correspond with the pinouts for confirmation, if so pay attention to pin 8, earth and check its good.
Dave
primo
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Post by primo »

Is there an automatic advance/retard system on your injection pump controlled by the ECU? Might it be that spiking the dash? Dave Burns also mentioned an earth problem previously. There is an earth point on the vestigal 'transmission tunnel' under the centre console which I have found to be troublesome. (Earth terminal on to painted surface and screwed down on to carpet and soundproofing etc., as if from new).
Tebster
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Post by Tebster »

Hi all,
After testing and comparing results with another xantia with climate control have found out the following.
1, When you connect the negative lead of a meter to the negative coil side of the aircon relay and attach the positive lead to the positive on the battery you get on my xantia 12.55 volts, on my friends car which is free from faults you get 8.9 volts.
2, If you repeat above test on the positive side you get 12.55 volts on both cars.
This would indicate that something is controlling the negative side of this relay, this measurement is the same as above with or without the bitron in the circuit on both cars.
Have looked at the schematic and it appears that this system has an air conditioning ecu (8080),apparently this was under or behind the glove box on earlier models but is enclosed in the heater assembly on later models, does anybody know if this is the case and can it be removed without taking the dash out.
Also would it be possible that a slightly leaking heater matrix may have damaged this ecu ? The reason I ask is because the matrix was leaking slightly but has now been stopped with stp leak fix.
Over the weekend I will be testing the ignition switch as advised on this forum just to rule it out, any thoughts on above will be appreciated.
Thanx
paul
davey
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Post by davey »

try isolating suspect devices ie pulling fuses on a/c, blower, etc. to leave minimum to start car. find it hard to believe a/c is causing your problems - it is more likely to be a knock on effect from another fault.
dave
Tebster
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Post by Tebster »

Hi,
Have tried what you suggested davey on several occasions without any luck,yesterday I located the climate ecu unplugged it and still the fault exists, also I tested the ignition switch and found a slight difference in voltages, going in to the switch it measured 12.55v and coming out was 12.35v,I removed it and carefully took it apart and found that the centre wire (red which goes to grey plug)had become loose and was not connecting properly inside the switch, also the rest of the contacts were very dirty, I cleaned it up and repaired the loose contact on the red wire, re-assembled it and thought that I may have cured the problem, but after testing the switch on the car there was no difference.
The only thing that I can think of that I havnt checked yet is the main multiplug on the drivers side bulk head, this though is hard to get to because the plastic scuttle panel has to be removed and is bonded in place, other than that I give up have run out of ideas, maybe a gallon of petrol and a box of englands glory will cure it.....lol
Dave Burns
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Post by Dave Burns »

What about the ECU, if thas got a mate with the same car can't tha try his ECU.
Dave
Tebster
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Post by Tebster »

Hi Dave,
Have already tried the ecu and still the same, the air con relay buzzes with or without the ecu in the circuit and fans still go hyper,the only way I can get a bit of normality to the cooling circuit is to totally remove the air con relay but still the main ecu is been affected, I know that this is a common fault thats creating these problems but just cant seem to find it,have tried and tested virtually every main component,checked / cleaned all multiplugs etc.
The only thing that I can think of now is that there may be a broken wire some where in the under bonnet loom, or in the loom which passes from the driver bulkhead to the passenger side of vehicle.
But checking this loom is near impossible with it still attached to the vehicle and replacement is not an option as it would probably cost me more than buying another older xantia.
Tebster
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Post by Tebster »

Hi,
Have been driving the Xantia all this week without the aircon relay plugged in,cooling system works as it should do but tacho still goes wild with the ignition switched on but without the engine running,when driving or ticking over it works fine.
Does anyone know what else is connected to the aircon relay other than the things I have already tried and tested ?
Thanx
Paul
Tebster
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Post by Tebster »

Hi everyone.
Well after 3 months of trying to sort out this problem and loads of money spent on various sensors etc, I have finally found the cause of my weird electrical problems.
The fault was in the main wiring loom on the drivers side front section, the loom travels across the front x member and up into the drivers wing,where the loom has a 90 bend in it at the bottom 12 wires had burnt together, some of them had just melted completely.
It looks as though the wires had been crushed by someone or something resulting in this mess.
Luckily I have loads of crimp terminals and just happened to have some of the heat shrink water proof type.
Wire by wire I cut and reconnected them and finished them off with the heat gun to ensure water tight connections, I then bound them in harness binding tape then put the orignal plastic sleeve back over them.
All is brilliant now, aircon works without fans on hyperdrive, tacho is stable and no more buzzing aircon relay plus ecu is behaving itself !
I would like to say thank you to everyone who has contributed in helping me, without this forum I dont think I would have ever attempted it !
Regards
Paul
paranoid
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Post by paranoid »

Wow......After reading all of that, I am genuinly happy for you [:)]
I would have give up long long time ago, did my dash bulbs today and found similar horror storys, where the plugs go into the clocks, looked like someone had grabbed the looms with point nose pliers and yanked them out out.
That was a lovely six hours just spent repairing wires that hadn't broken yet!!!![V]But would have just as I got it all together[;)]
vanny
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Post by vanny »

wow! That wasnt a story, that was an epic!
Im amazed you stuck with it for so long, but praise to you for getting to the end of it!
I guess its a good job the welded wires didnt decide to go sky high!
Bet your enjoying the air con again though :D
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