Electronic speedometers - How do they work?
Discussion
Give me a cable and a skew gear any day! Digital speedo readout has failed on Daughter's Twingo (The old sort not the modern one!)
It's not just the bulb in the instrument and there's no sign of any chafing of the wiring as far as I can see towards the gearbox.
Of course, Dad is supposed to be an expert on anything mechanical and I recognise that a visit to the Renault dealer will cost more than the car is worth.
Any iideas on where to start looking? Is there a sender in the gearbox and how is it driven? Are they reliable?
It's not just the bulb in the instrument and there's no sign of any chafing of the wiring as far as I can see towards the gearbox.
Of course, Dad is supposed to be an expert on anything mechanical and I recognise that a visit to the Renault dealer will cost more than the car is worth.
Any iideas on where to start looking? Is there a sender in the gearbox and how is it driven? Are they reliable?
If its the new twingo, i.e. Mk2.
The wheel speed sensors send their signals to the ABS computer for its operations, the abs computer calculates the vehicle speed and transmits it to the dash board via a data bus called C.A.N. (Controller Area Network).
Renault use a protocol called CANOpen modified for their own standard.
Is it digital or dial meter?
There was a report on Watchdog recently about scenic dashboards failing, so it may also be an issue for Twingo's.
Would suggest taking a look at www.renaultforums.co.uk and see if there are any more reports of dash failure on these.
My concern is that you're not seeing any other issues other than the speedo.
The wheel speed sensors send their signals to the ABS computer for its operations, the abs computer calculates the vehicle speed and transmits it to the dash board via a data bus called C.A.N. (Controller Area Network).
Renault use a protocol called CANOpen modified for their own standard.
Is it digital or dial meter?
There was a report on Watchdog recently about scenic dashboards failing, so it may also be an issue for Twingo's.
Would suggest taking a look at www.renaultforums.co.uk and see if there are any more reports of dash failure on these.
My concern is that you're not seeing any other issues other than the speedo.
Older stuff used a pulse sender, like a cam or crank sensor that detects movement of the output shaft on the gearbox, and it's probably this.
If it is, other speed sensitive things will go funny too, mpg gauges, speed sensitive wipers too.
More modern stuff uses the ABS wheel speed sensors, and this is integrated into any traction control systems, so you normally get an ABS light on too.
Have a check around to see if any other speed sensitive functions are there, and if they still work. If they do, then the problem lies with the cluster, if they don't then it's most likely the sender.
If it is, other speed sensitive things will go funny too, mpg gauges, speed sensitive wipers too.
More modern stuff uses the ABS wheel speed sensors, and this is integrated into any traction control systems, so you normally get an ABS light on too.
Have a check around to see if any other speed sensitive functions are there, and if they still work. If they do, then the problem lies with the cluster, if they don't then it's most likely the sender.
Thanks lads. It's a MK1 Twingo about '93. Don't think there's anything else speed sensitive to verify. certainly there are no other faults with the car.
Renault site is a good idea and time to venture underneath to the gearbox connection.
I wondered if there's any way of getting a multimeter reading off the wires to the cluster.
Renault site is a good idea and time to venture underneath to the gearbox connection.
I wondered if there's any way of getting a multimeter reading off the wires to the cluster.
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