its not a mechanical drive that i'm used too, so where to start with for fault finding? Is there some kind of standard diagram? the instruments appear to be labelled 'CA' - can post up pics if it helps.
Thanks in advance!
As above really. All other electrics are now working no the car expect the speedo.
its not a mechanical drive that i'm used too, so where to start with for fault finding? Is there some kind of standard diagram? the instruments
appear to be labelled 'CA' - can post up pics if it helps.
Thanks in advance!
They can work in one of three ways, usually: by taking signals directly from the car's ECU, by means of a Hall Effect sensor attached to the
gearbox cable connection, which 'counts' the rotations of what would be the speedo cable connection, or by counting magnetic pulses from
magnets attached to the propshaft or a hub.
The latter is most common, and least reliable... it is quite sensitive to the position of the magnets and their clearance to the pickup, and can often
become faulty due to build up of dirt on the sensor, the sensor position being disturbed, corrosion of the wiring connections to the sensor, or simple
loss of a magnet (they're often epoxied in place, and simply drop off!).
'CA' sound like the CAi logo Caerbont Automotive Industries, who now also do the traditional 'Smiths' instruments. The
'i' of the logo is just a dot over the italicized serif of the 'A', so it's easy to misread!
Information here may be useful.
If you have a digital multimeter set it to a low range and you should be able to read the pulses from the sensor.
quote:
Originally posted by Sam_68
They can work in one of three ways, usually: by taking signals directly from the car's ECU, by means of a Hall Effect sensor attached to the gearbox cable connection, which 'counts' the rotations of what would be the speedo cable connection, or by counting magnetic pulses from magnets attached to the propshaft or a hub.
The latter is most common, and least reliable... it is quite sensitive to the position of the magnets and their clearance to the pickup, and can often become faulty due to build up of dirt on the sensor, the sensor position being disturbed, corrosion of the wiring connections to the sensor, or simple loss of a magnet (they're often epoxied in place, and simply drop off!).
'CA' sound like the CAi logo Caerbont Automotive Industries, who now also do the traditional 'Smiths' instruments. The 'i' of the logo is just a dot over the italicized serif of the 'A', so it's easy to misread!
Information here may be useful.
quote:
Originally posted by NorfolkluegojnrI'll see what i can see with the car up on ramps - how big is the pick up?
Presume you can replace the magnets?
Great thanks. Will have a look over the weekend.
LCB to the rescue as always! 