Intermittent Speedo?
Discussion
Just been out for a short-ish drive in the Chimaera, 1st one for 10 days or so.
as soon as I set off I noticed that the speedo, odometer and trip meter weren't working and only worked for a short proportion of the trip, flicking on and off every so often.
I've checked in the bible and it says likely cause is either faulty sensor, or bad connection at either sensor end or speedo end.
Bearing in mind I'm mechanically incompetent, how easy is it to investigate this, or do I just get to a garage a.s.a.p?
Help appreciated, as always
as soon as I set off I noticed that the speedo, odometer and trip meter weren't working and only worked for a short proportion of the trip, flicking on and off every so often.
I've checked in the bible and it says likely cause is either faulty sensor, or bad connection at either sensor end or speedo end.
Bearing in mind I'm mechanically incompetent, how easy is it to investigate this, or do I just get to a garage a.s.a.p?
Help appreciated, as always
Good to see you back on here again, I hope all is well. 
You've pretty much summed up the diagnosis. Perhaps the easiest to check is the transducer(sensor) which could have moved, got covered in debris or be suffering from a poor connection. Location I think depends on which gearbox/diff set up you have but it is basically accessible from underneath, whereas the speedo might need the dash top removing??
A more knowledgeable bod will be along in a minute.
You've pretty much summed up the diagnosis. Perhaps the easiest to check is the transducer(sensor) which could have moved, got covered in debris or be suffering from a poor connection. Location I think depends on which gearbox/diff set up you have but it is basically accessible from underneath, whereas the speedo might need the dash top removing??
A more knowledgeable bod will be along in a minute.
Mike, sounds similar to the problem I had last year, ended replacing the sensor.
However you could check the sensor is clean and has the correct gap set between it and the half shaft.
The sensor is mounted on the diff, assuming you have the T5 box (reverse right and down,ie below fifth)
It looks like a big brass bolt which has a small tip at the end which is adjusted to just miss the teeth on the half shaft. At the other end a cable comes out which goes up into the car just underneath the little "trinket" tray in the center console near your left elbow.
Check that the end of the sensor is clean and adjust it to about 6-8 thou' with feeler gauges between the tip and the half shaft teeth. Double check that it doesn't hit the teeth when you rotate the off side wheel.
If after that the speedo still doesn't work then a new sensor may be required. Cost about forty quid.
Hope that helps.
Cheers.
Paul
However you could check the sensor is clean and has the correct gap set between it and the half shaft.
The sensor is mounted on the diff, assuming you have the T5 box (reverse right and down,ie below fifth)
It looks like a big brass bolt which has a small tip at the end which is adjusted to just miss the teeth on the half shaft. At the other end a cable comes out which goes up into the car just underneath the little "trinket" tray in the center console near your left elbow.
Check that the end of the sensor is clean and adjust it to about 6-8 thou' with feeler gauges between the tip and the half shaft teeth. Double check that it doesn't hit the teeth when you rotate the off side wheel.
If after that the speedo still doesn't work then a new sensor may be required. Cost about forty quid.
Hope that helps.
Cheers.
Paul
Have just replaced my sensor, cost about £65
Make sure the feeler gauge fits between the sensor tip & every single tooth on cog wheel (check by rotating rear wheels all the way round)
I did mine & 1st only checked with the feeler gauge when the back wheels were stationary, i did rotate the rear wheels to make sure nothing was rubbing before dropping off stands
Then drove the car 50 metres down the road & heard nasty metal grinding sounds
Got it straight back on the axle stands & thankfully hadn't wrecked the sensor, readjusted the gap & all is well
I did find the gap had to be very small to work correctly
I used the thinnest feeler gauge to gap it
I would recommend re-adjusting & cleaning your old one 1st, as others have adviced
I strongly suspect my old one was ok & just needed adjusting
Just didn't realise how critical the gap acuracy had to be
Its a bit fiddly but only takes about an hour to do
Good luck with it...
Make sure the feeler gauge fits between the sensor tip & every single tooth on cog wheel (check by rotating rear wheels all the way round)
I did mine & 1st only checked with the feeler gauge when the back wheels were stationary, i did rotate the rear wheels to make sure nothing was rubbing before dropping off stands
Then drove the car 50 metres down the road & heard nasty metal grinding sounds
Got it straight back on the axle stands & thankfully hadn't wrecked the sensor, readjusted the gap & all is well
I did find the gap had to be very small to work correctly
I used the thinnest feeler gauge to gap it
I would recommend re-adjusting & cleaning your old one 1st, as others have adviced
I strongly suspect my old one was ok & just needed adjusting
Just didn't realise how critical the gap acuracy had to be
Its a bit fiddly but only takes about an hour to do
Good luck with it...
Mine seems to stop working or become intermittent after about 60 miles - Then after you stop and drive it next time it is fine. Only seems to be an issue after driving for about 60 miles/an hour. (has happened 4 times after almost identical journey distances / times.
My car was serviced last week and they took it off and cleaned it up and checked the gap, but had the same problem on monday morning after 60 miles.
Has anyone else had this? where it stops after the same sort of distance - do you think it is heat related, or adjusting the gap will help? Or is it just easier and quicker to replace it?
Anyone know what car the part is off?
Cheers,
Tim.
My car was serviced last week and they took it off and cleaned it up and checked the gap, but had the same problem on monday morning after 60 miles.
Has anyone else had this? where it stops after the same sort of distance - do you think it is heat related, or adjusting the gap will help? Or is it just easier and quicker to replace it?
Anyone know what car the part is off?
Cheers,
Tim.
Timja said:
Mine seems to stop working or become intermittent after about 60 miles - Then after you stop and drive it next time it is fine. Only seems to be an issue after driving for about 60 miles/an hour. (has happened 4 times after almost identical journey distances / times.
My car was serviced last week and they took it off and cleaned it up and checked the gap, but had the same problem on monday morning after 60 miles.
Has anyone else had this? where it stops after the same sort of distance - do you think it is heat related, or adjusting the gap will help? Or is it just easier and quicker to replace it?
Anyone know what car the part is off?
Cheers,
Tim.
Mine was similar, although it used to fail after about 10 miles, then start again after a few more.My car was serviced last week and they took it off and cleaned it up and checked the gap, but had the same problem on monday morning after 60 miles.
Has anyone else had this? where it stops after the same sort of distance - do you think it is heat related, or adjusting the gap will help? Or is it just easier and quicker to replace it?
Anyone know what car the part is off?
Cheers,
Tim.
It was adjusted without real improvement - I'd suggest replacing it.
As has been said earlier, adjust the sensor as close to the teeth of the cog as you can without it touching when you rotate the wheel. You'll need a very large adjustable spanner and axle stands.
It's not a part from any other car - but it's easily obtainable through most TVR parts suppliers.
Paul
Mine is very sensitive to the gap between the sensor and the toothed wheel on the diff. Having had the diff in and out a few times I often find when I get the car back that the speedo only starts to work above a certain speed, adjusting the sensor closer solves the problem. If nothing has been touched in that area then maybe the connecting wire has a loose connection somewhere, or something has got onto the sensor tip.
Whlist investigating the sensor I found the connection form the sensor to the wire running under the car was only made by twisting the bare ends and taping up!
Whlist investigating the sensor I found the connection form the sensor to the wire running under the car was only made by twisting the bare ends and taping up!
Gassing Station | Chimaera | Top of Page | What's New | My Stuff