Speedo & Odometer

[alan_pickering]

Hi Guys

Help please.
My speedo on my 2000 Chim has suddenly started showing me doing either zero or 180 mph.

Meanwhile the odometer seen to be logging three miles for every one actually travelled !!!!!.

Is it 'back to garage' or somthing simple that I can fix?.

All thoughts and advice welcomed.

Alan P

[TvrToe]

Alan. 'fraid I can only sympathise with your predicament , having similar problem with my '95 chim. Changed the speed sensor, but no change, investigations ongoing. The odometer readout is proportional to speed, hence high indicated speed = high mileage.

[chris_chim]

TvrToe said:

The odometer readout is proportional to speed, hence high indicated speed = high mileage.

Is this true? I agree if the sender is faulty the odo will misread but I assumed my 10% over reading speedo had no effect on the odo (unless my journey to work has shortened by 3 miles since I got the chimaera?).

[TvrToe]

Chris_chim, check out the bible; it says the speedo is required by law to be within 10% and relates rolling circumference of the wheel to the distance travelled.

[chris_chim]

I thought the law required within 10% at 30 rather than throughout the range. Anyway mine over reads by 10% at 70 as I have measured it with GPS and the error increases as speed increases, it is accurate at 30. The revs vs indicated speed in top agree with all other posts on here so I assume they all over read at speed (on standard tyre sizes). I know my odo is accurate as it measures 30 miles for a known 30 mile journey regardless of speed, I would notice if it over read by 10%.