Common causes of rev counter failure?

adamskibx · Post by **adamskibx** » Sun Nov 12, 2006 5:00 pm

Please let me know if im posting something I shouldnt, but the revcounter in the CX does not work, and there is a new one on ebay that ends very soon. Is it common for a revcounter to fail, or is it more likely to be a contact somewhere else? Im useless with wiring diagrams so cant work out what sends a signal to it.

Cheers, Adam

sleepy0905 · Post by **sleepy0905** » Sun Nov 12, 2006 5:15 pm

Its usually a signal from the ignition (Petrol) or a pickup from the flywheel (Diesel) the bx diesel pickup can fail causing the rev counter to not work but the petrol variant gets a pulse from the ignition so it would be worth checking the connections the guage itself is unlikely to fail but that is not saying they dont as they are usually prety bomb proof but I cannot give you exact info as i dont and never have owned a CX

ken newbold · Post by **ken newbold** » Sun Nov 12, 2006 6:26 pm

It used to work on my CX SOMETIMES, but every now and then it would go bezerk and then settle down again, until the next time the car broke down

ellevie · Post by **ellevie** » Sun Nov 12, 2006 6:39 pm

On the 19TRS it's one of the four spade connectors on top of the ignition coil. It's the one which doesn't cut the engine out if you pull it off.

AlanS · Post by **AlanS** » Sun Nov 12, 2006 7:59 pm

ellevie wrote:On the 19TRS it's one of the four spade connectors on top of the ignition coil. It's the one which doesn't cut the engine out if you pull it off.

On the petrol series one CXs it's as ellevie describes above. Usually it's caused by the wire getting hard just where it is attached to the spade terminal that connects to the coil and it breaks internally.
In 22 years of owning Cits, mainly CXs I've never heard of a tacho failing, so you'd have to be a bit stiff if yours has chucked it in. I'd be inclined to find the terminal, chop it off and fit a new one, clean up the terminal on the coil and see how it goes. A thorough checking of the wire if it still is no go might be worth the effort.

Alan S

thanuttiscotsman · Post by **thanuttiscotsman** » Sun Nov 12, 2006 8:00 pm

hi there,
if its a petrol engine then the signal comes from the ign coil. the is a 4 port connector that goes onto the coil and it is quit easy to figure which one it is!! one is power supply and is normally brown or yellow, one wire goes to a dead end where there is a normally black female connector, the third one comes from the ign module ( looks like a big computer chip and finally the only other one is the one your looking for. these thaco wires tend to break as they are too thin and usually break round about the bulkhead area. im sure that is your problem. oh yeah the other option is corrosion on the connectors again near the bulkhead.

cheers rossco

adamskibx · Post by **adamskibx** » Mon Nov 13, 2006 12:26 pm

Cheers for the tips guys. I did take the dash apart and removed the revcounter drum (bathroom scales type revcounter) I couldnt see anything obviously wrong, but I suppose its possible that a capacitor has died or something. Much more likely is that it is a connector in the engine bay somewhere. I have checked the wires on the coil (well, it was dark by this point so I just unplugged them then plugged them back in again. Ill check the whole length of wire for signs of cracking etc next weekend.

thanuttiscotsman · Post by **thanuttiscotsman** » Mon Nov 13, 2006 5:54 pm

hi there,
dont waste all your time checking the whole length of wire it will take ages.m just take a 2 meter piece of wire connect on end to the coil and other to the tacho. if tacho works then install new wire if not then there is another problem.

rossco

Way2go · Post by **Way2go** » Mon Nov 13, 2006 5:58 pm

thanuttiscotsman wrote:hi there,
dont waste all your time checking the whole length of wire it will take ages.m just take a 2 meter piece of wire connect on end to the coil and other to the tacho. if tacho works then install new wire if not then there is another problem.

rossco

It's a good suggestion but you have to be very careful & sure that you are connecting to the right points or................

thanuttiscotsman · Post by **thanuttiscotsman** » Mon Nov 13, 2006 6:07 pm

hi there,
of course!!:D but i thought that was obvious!

it will be easy to identify as it'll be right behind the tacho. there is a block 2 pin connector. connect your new wire to one of them if the tacho works cool if not try connecting the wire to the other pin in the connector if it still dont work then its another problem. dont worry about shorting it just do a simple test with testlamp first or a bot o wire wi a buld in middle.

rossco

adamskibx · Post by **adamskibx** » Mon Nov 13, 2006 6:45 pm

Good plan Rosco- The back of the revcounter is plastic, where two terminals emminate. The printed circuit board (that green flexible stuff) then joins on and goes straight to a connector with loads of connections on (but I can see where the revcounter ones end).

The way the bidding has gone on the one on ebay, I dont know whether thats a sign that they fail or a sign that people have got desperate like me:-)

http://cgi.ebay.co.uk/CITROEN-CX-TACHO- ... dZViewItem

thanuttiscotsman · Post by **thanuttiscotsman** » Mon Nov 13, 2006 9:01 pm

hi there,
even if you need to replace the dash you can prolly get a scrappers one, may even give the milage a haircut and make you feel better about the car.

cheers rossco