Xantia Speedo Failed

StevieM · Unread post by **StevieM** » 02 Jan 2010, 17:29

Wonder If anyone can help.
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Speedo/odometer operation has been intermittent over past few weeks.
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It currently does not work...seems to coincide with cold weather.
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I have sprayed contact cleaner into the sensor connector, then tried to remove sensor...this resulted in g/box oil pouring allover my blk-paved drive! (should this really happen, or is my g/box oil level too high????)
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O-ring obviously still intact as no leaks since doing this.
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Does anyone have any idea as to the failure rate of these sensors?
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I have scoured far and wide as to possible causes including:
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a) soldered joints on instrument panel pcb
b) speedo module behind glovebox bad
c) faulty ignition switch
d) faulty wiring between sensor and module
e) poor sensor/earth
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I think I may need to drain my gearbox oil to be able to remove sensor without fther mess, to test (maybe ohm meter across the non-earth pins to chk continuity????)
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If anyone can post their experiences, it may determine in which order I dive into the above to attempt to eliminate.
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Happy New Year

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Kind Rgds, Steve

Unread post by **Peter.N.** » 02 Jan 2010, 18:37

Hi Steve

I have had this problem on a couple of XMs and in both cases it was a bad joint on the instrument panel, on the back of one of the plugs.

I think you have to much oil in your gearbox, unless the car was leaning to the o/s - better than to little though.

Peter

Unread post by **citroenxm** » 02 Jan 2010, 22:24

Xantia SPEED Sensors fail quite commonly, Ive had to change 3 of them..

Never really had a problem with soldered joints on XANTIA instruments, so I Hedge my bets on the SPEED sensor itself in the top of the output house for the DRIVERS SIDE drive shaft...

Paul

Unread post by **CitroJim** » 02 Jan 2010, 22:43

It'll be quite normal for oil to pour out of a manual 'box if you remove the speed sensor. That bit of it is pretty full..

Only on the automatics is it safe to remove the speed sensor without draining the 'box. In fact I have pre-filled autoboxes through the speed sensor hole before now...

Paul, am I correct in believing the speed sensor is the same right across the range provided it has three pins in the socket?

They all look much the same...

Unread post by **citroenxm** » 02 Jan 2010, 22:44

Yes, but I guess a different PLASTIC drive cog inside the box would be fitted depending on the size of wheel, to prevent speedo incorection..

Paul

StevieM · Unread post by **StevieM** » 03 Jan 2010, 10:44

Many thanks for all this info.
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If I sourced some small female spades, with sensor connector disconnected, does anyone know which 2 pins of the sensor I may expect to observe a tiny voltage if I put a DVM on most sensitive range across them, spinning the OSF wheel while up on stands???
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Thanks again, Steve

citronut · Unread post by **citronut** » 03 Jan 2010, 10:57

i have never had gear oil spill out when removeing the speed sensor from a manual box,

but i have always done this on level ground,

if your car is/was on level ground you might find your box over full, and this could be the cause of the speed sensor failiure, as it to might be full of oil,

regards malcolm

StevieM · Unread post by **StevieM** » 03 Jan 2010, 23:23

Speedo decided to start working again!!!.
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Saw this as an opportunity to see what the sensor does when functional, so can compare when stops again (and I know it will!!).
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connected spades/test wires to sensor to interace with DVM.
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Static resistance across all permutations of the 3 x pins....only 2 x combinations showed approx 10 Mohms, in 1 direction only.
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Up on stands, son in car to engage 1st gear...held NSF wheel still to force OSF one to turn........NIL hint of any voltage, AC, or DC, across any of the pairs of contacts, whilst the speedo-driven driveshaft was spinning
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Normalised everything....confirmed speedo still operational.
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Simple AC voltage measurements obviously meaningless
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Will test further when fails again, although I'm still at a loss as to cause.
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Rgds, Steve

Unread post by **Peter.N.** » 03 Jan 2010, 23:32

Hi Steve

I think that the output is quite miniscule, you will probably need a scope to read it.

Peter

Unread post by **CitroJim** » 04 Jan 2010, 06:45

As far as I know, it's a little alternator in there so the output will be small and as Peter says, a 'scope will be needed to see anything.

I'd expect the waveform to vary in amplitude and frequency vs. speed of rotation.

citronut · Unread post by **citronut** » 04 Jan 2010, 09:19

dose this car have ABS, as i have always been told you must not run up any of the wheels with the others stationery, as it can upset the ABS somewhere along the line,

also if you remove the transducer from the car and try to open it up, give a good clean and re/assemble, as it could just be swimming in oil inside,

regards malcolm

Unread post by **CitroJim** » 04 Jan 2010, 09:56

I don't think you'll find them very amenable to being opened up Malcolm

StevieM · Unread post by **StevieM** » 04 Jan 2010, 12:15

Nil ABS.
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Read somewhere on web that most of these behave the same....approx 0.3-0.5v AC can be measured when spinning reasonable rate.
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Tks for input.
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If I was confident sensor was OK, I would take the trouble to remove instrument panel, chk joints.....last resort for me though.
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Maybe I'll just replace when plays up next, just to eliminate....read these approx £60 from Citroen (maybe wrong)
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I do want to take trouble to sort this out.....this is 16v petrol 99000 miles .....replaced many bits over past few years:
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all brake pads
radiator
cat
rear box
all spheres
pinion valve (4 hrs under car!!!)
hydraulic pump
coil pack
cambelt + w/pump + aux belt
battery
4 hours repairing indicator switch (relay was buzzing)
replaced s/roof motor
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It drives really nicely...probably spent 6-7 times its value on this work....most people don't understand why I bother...just think I can make it last forever if I look after it.
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Rgds, Steve

citronut · Unread post by **citronut** » 04 Jan 2010, 14:01

i belive GSF do sell the transducer's,

ask our inside man Vince

regards malcolm

thorter · Unread post by **thorter** » 04 Jan 2010, 20:24

According to a description of the 806 DW10 that was on the web at one time (perhaps search for B1BBM2K1), the speed sensor is a Hall effect device, so needs power. Likely to be the same across the PSA range.

Pinout
Pin 1 +12volts
Pin 2 Earth
Pin 3 Signal

Signal is a square wave or pulse, I think 5 impulses per wheel rev.

Fred