Xmv6, Tacho not working

[paulxmski]

Hi all,
Fixed the not starting problem seemed to be the relays. One relay had a burnt bit with evidence of slight melting on one leg so I replaced that from my other XM. On start up I heard a noise a bit like arcing from the HT but not that. I stopped the engine whence I heard a bang not very loud thought it might have been slight pre-ignition. Looked around again restarted and set off up the road then noticed the tacho needle is right over the other side permanently! can anyone say if the relays on the control box are responsible for connecting the tacho. Maybe I put the wrong relay on, although I did check to see it has the same connection diagram on the side and is the same amps??? I don't seem to be able to find any info on the relays from Hay*** or Russ**.

Thanks Paul??

[citroenxm]

Hi Paulxmski

Glad my advice prevented you from removing all things IR-RELEVENT like the LHM resviour...

Cant help you with the rev counter, I beleve it takes it readings from the coil be measuring the spark pulse's..

I'm more used to the Diesel type that connects to a Flywheel sensor, but I know Petrol ones dont always..

Good luck with the diagnostic..

citroenxm

[paulxmski]

Hi citreonxm,
Yes sure did help that since I was ready to dive in there and you prompted me to think on those relays since I had probs with them before
Thanks again Paul

[paulxmski]

Hi all,

Being as it was a much milder day today I decided to go and have a butchers at the full on stuck tachometer needle. Seeing as there are only 2 screws to undo to get the binnacle off the instrument cluster and 4 to oyk out the cluster it all went easypeasy. When I undid the four little screws at the bottom of the cluster the plastiglass came away from the body and the needle suddenly sprang back to zero.voila! oopla! toad in ze ole how you say iit . reassembled the cluster reglued the pads on the back and ensured the locating rubbers at the top front went back in the right place job done! Next had another check of the relay which appeared to be correct and then fingers crossed started the engine. Perrfect tacho showing the correct revs and all ok. I can only think that when I put the relay in the first time it was in the open state and that this allowed a surge through to the tachometer, but really it's a mystery.

Paul.

[Peter.N.]

Any arcing on the electrics that reaches the tacho will be interpreted as a very high speed signal, so I expect thats what the problem was, never heard of it happening before though.

Peter.N.

[paulxmski]

Hi Peter thanks for that snippet yes when the RAC mech came to look at the car he stuck his tester in the coil output and asked me to turn the engine over which caused the tester to light up thus proving the coil wasn't dead. I have heard that the tachometer works off the coil on the V6 So maybe this `primed' the tacho with some high voltage somehow especially since the whole lot was dripping in WD40.


Paul

This post has been edited by paulxmski on January 14, 2006 10:44 pm