Xantia rev counter

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Jshodgson
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Xantia rev counter

Post by Jshodgson »

today my rev counter stopped working. Then it started again. Then it stopped. Then it started again.
Are there any reasons other than the cable becomming loose? (which I haven't checked yet)
It happened when I was doing about 3000 rpm, it just dropped dead.
It happened at the same time as one of the instrument lights failed. This is now the third bulb to fail in the last couple of weeks.
beezer
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Post by beezer »

Correct me if I'm wrong but doesn't the rev counter work on pulses from a sensor rather than a mechanical cable? If so then a fault in the wiring may have caused your instrument light to blow and affect the rev counter as well.
Jshodgson
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Post by Jshodgson »

Thanks Beezer.
Can you (or anyone else!) give any tips as to what and how to check the wiring for the rev counter or if there are any obvious areas to check.
Also is it likely to spead to other instrument parts? I think I could live with a few bulbs blown and the rev counter not working, but the speedo and things like the indicators would be a nightmare.
Thanks
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uhn113x
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Post by uhn113x »

Hi JS
There may be no connection (PNI) between your rev counter problem and bulb failure, but check your battery voltage with the engine running at 1500-2000 rpm - should be no more that 14.8 - if it is, the regulator in your alternator has a fault.
The rev counter is almost certainly the sender unit going open-circuit intermittently. On a ZX it is on rear top of the bell housing - Xant probably the same. Just slacken the bolt to pull it out.
I would think that as all the instrument bulbs are the same age, it would pay to change the lot in one go.
The indicators are nothing to do with your instruments.
HTH
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Jshodgson</i>

Thanks Beezer.
Can you (or anyone else!) give any tips as to what and how to check the wiring for the rev counter or if there are any obvious areas to check.
Also is it likely to spead to other instrument parts? I think I could live with a few bulbs blown and the rev counter not working, but the speedo and things like the indicators would be a nightmare.
Thanks
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
ghostrider
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Post by ghostrider »

Hi Js, I have the same problem on mine, finally got round to checking it the other day with my multimeter that has a frqency counter on it, and sure enough when the rev counter stopped working there were no pulses from the sensor which is at the back of the engine on the flywheel end, the connector is on top of the gearbox and is either grey or brown depending on the year with two wires and an overall screen on the sensor side and just two wires on the loom side of the connector. I think that the fault must be temperature dependant as mine always packs up at exactly the same point in my journey each day, I thing the resistance across the sensor coil is about 160 K Ohms
Pete
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Forth
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Post by Forth »

The rev counter works intermittently (seems accurate when it operates, though usually it does not) on ours as well; it's a late Mk.1 Xantia .... but the bulbs are all ok and no dashboard lights are affected by its behaviour at all.
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Post by Forth »

"I think that the fault must be temperature dependant as mine always packs up at exactly the same point in my journey each day"
Not totally sure on that... if ours works it is true enough more likely to be on starting off, but there has been the occasional - always brief - interlude of it deciding to start operating in the middle of a journey as well.
JohnCKL
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Post by JohnCKL »

Same on my 96 1.9XTD, just happened a few months ago.
dnsey
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Post by dnsey »

Is the sensor getting wet, by any chance?
My speedo packed up recently after driving through very heavy rain, but recovered after a few hours drying out, and has been fine ever since.
Forth
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Post by Forth »

The conditions for potential wetness do not seem to be a factor.
Jshodgson
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Post by Jshodgson »

Hi ghostrider,
where do I find the sensor. I ttok off my air filter housing to get a better look and founf a couple of cables which I tried to follow back. Still couldn't find it. '95 Xantia TD LX.
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by ghostrider</i>

the rev counter stopped working there were no pulses from the sensor which is at the back of the engine on the flywheel end, the connector is on top of the gearbox and is either grey or brown depending on the year with two wires and an overall screen on the sensor side and just two wires on the loom side of the connector. I<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Richard Gallagher
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Post by Richard Gallagher »

It sits on top of the gearbox bellhousing at the point where the gearbox joins onto the engine.
Jshodgson
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Post by Jshodgson »

Ghostrider,
my rev counter problem sounds like yours. Mine fails after about 3 miles each day then starts again when I've left the car for a bit.
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uhn113x
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Post by uhn113x »

The tacho sensor consists of a coil with many turns of fine wire wound on a ferrite core; all this is moulded into plastic. The problem is that a break develops in the connection between the coil and the connector on the unit, and temperature changes and vibration cause it to make and break.
davethewheel
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Post by davethewheel »

common problem i replaced one of mine from a scrapped car.
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