Speedo Problem
Discussion
Help!
I have recently become the (proud) owner of a 95 4.0 Chimaera, but it has a problem with the speedo. It is currently with a main dealer (name withheld) to sort out a number of minor problems and anoying niggles. One of these is that the speedo doesn't work under about 17/18 mph and drops of to zero under this speed. This is not only annoying but means I am losing mileage in traffic. The dealer has tried adjusting the pickup gap to no avail and has tried several different heads on the car - all of which drop off to zero at a variety of speeds. They say that I therefore am stuck with the problem and that all Chims do that to a certain degree. Old paperwork in the car indicates that the problem has been looked at several times - if this is the case, the previous owners obviously never left the garage with the impression that it 'had to be like that'. I have since sat in 3 other Chims and a Grif and they all work fine. Another (main) dealer has said the line I am being sold is nonsense. I also wonder if such a fault is legal for an MOT. The speedos can apparently be checked by an independent firm but I think if the garage have tried different heads, I should insist on a new/second hand sender unit and pickup. Any ideas.
I have recently become the (proud) owner of a 95 4.0 Chimaera, but it has a problem with the speedo. It is currently with a main dealer (name withheld) to sort out a number of minor problems and anoying niggles. One of these is that the speedo doesn't work under about 17/18 mph and drops of to zero under this speed. This is not only annoying but means I am losing mileage in traffic. The dealer has tried adjusting the pickup gap to no avail and has tried several different heads on the car - all of which drop off to zero at a variety of speeds. They say that I therefore am stuck with the problem and that all Chims do that to a certain degree. Old paperwork in the car indicates that the problem has been looked at several times - if this is the case, the previous owners obviously never left the garage with the impression that it 'had to be like that'. I have since sat in 3 other Chims and a Grif and they all work fine. Another (main) dealer has said the line I am being sold is nonsense. I also wonder if such a fault is legal for an MOT. The speedos can apparently be checked by an independent firm but I think if the garage have tried different heads, I should insist on a new/second hand sender unit and pickup. Any ideas.
Its certainly not normal behaviour. The speedo in mine is at best a random number generator, but it works from about 5mph upwards.
If both ends of the circuit have been checked, then its obviously something inbetween. I don't know how the speedo is wired to the sensor, but personally I'd consider testing the car with your own wiring installed, with a view to making it permanent.
If both ends of the circuit have been checked, then its obviously something inbetween. I don't know how the speedo is wired to the sensor, but personally I'd consider testing the car with your own wiring installed, with a view to making it permanent.
Might be a shot in the dark, but my speedo died the other day, then came back to life, then bounced around a bit and then died again.
Turned out that the Speedo transducer on the diff had packed up - new one fitted and no probs. Can be a bitch of a job depending where its been fitted - on mine the garage had to drop out the exhuast, prop and the diff to get at it and then it was welded on after many years of crap being flung at it!
Speak with the chaps at Fernhurst - they are excellent and will probably sort this in a jiffy!
HH
Turned out that the Speedo transducer on the diff had packed up - new one fitted and no probs. Can be a bitch of a job depending where its been fitted - on mine the garage had to drop out the exhuast, prop and the diff to get at it and then it was welded on after many years of crap being flung at it!
Speak with the chaps at Fernhurst - they are excellent and will probably sort this in a jiffy!
HH
parrot of doom said:
Its certainly not normal behaviour. The speedo in mine is at best a random number generator, but it works from about 5mph upwards.
If both ends of the circuit have been checked, then its obviously something inbetween. I don't know how the speedo is wired to the sensor, but personally I'd consider testing the car with your own wiring installed, with a view to making it permanent.
Thanks - might give it a go if the garage don't get any further.
herbie hammer said:
Might be a shot in the dark, but my speedo died the other day, then came back to life, then bounced around a bit and then died again.
Turned out that the Speedo transducer on the diff had packed up - new one fitted and no probs. Can be a bitch of a job depending where its been fitted - on mine the garage had to drop out the exhuast, prop and the diff to get at it and then it was welded on after many years of crap being flung at it!
Speak with the chaps at Fernhurst - they are excellent and will probably sort this in a jiffy!
HH
Thanks Herbie. Maybe your problems changing the transducer are why the garage aren't so keen to change mine! If I don't get any further, I might try Fenhurst - Thanks for the reply.
My speedo died a couple of days ago. One minute I'm doing a steady 50mph through motorway roadworks, the next minute it's reading zero. It's not budged since. I've checked the fuses and had a look at the speed sensor. I've given it a good soaking in WD40 as a prequel to attempting to remove it.
Is there any way of bench testing the sensor off the car?. The bible makes reference to connecting it to an oscilloscope whilst still on the car and rotating the back wheel. This doesn't seem that practical given that I don't own an oscilloscope.
I'm thinking it's possible that some crud or a foreign object could be lodged in the small gap between the toothed wheel on the driveshaft and the sensor. If I unscrew the sensor from it's mounting to clean and inspect it, how do I regap it to the toothed wheel? Do I need to use a feeler gauge, and if so which one?
If I want to try a a new sensor, are they all the same and how much is the part likely to cost?
I'd really like to try and fix it myself if I can. Failing that is an auto electrician likely to be able to assist or am I in for a trousering at the stealers?
>> Edited by sparkythecat on Wednesday 22 June 21:52
Is there any way of bench testing the sensor off the car?. The bible makes reference to connecting it to an oscilloscope whilst still on the car and rotating the back wheel. This doesn't seem that practical given that I don't own an oscilloscope.
I'm thinking it's possible that some crud or a foreign object could be lodged in the small gap between the toothed wheel on the driveshaft and the sensor. If I unscrew the sensor from it's mounting to clean and inspect it, how do I regap it to the toothed wheel? Do I need to use a feeler gauge, and if so which one?
If I want to try a a new sensor, are they all the same and how much is the part likely to cost?
I'd really like to try and fix it myself if I can. Failing that is an auto electrician likely to be able to assist or am I in for a trousering at the stealers?
>> Edited by sparkythecat on Wednesday 22 June 21:52
ed400 said:
The speedo is electronically driven from the gearbox. Check the wiring to the sensor as its more than likely corroded or loose. That was the problem with mine anyway! Hope that helps.
IIRC that's only on the cars with Rover gearboxes.
The cars with Ford Gearboxes have a toothed wheel on the differential driveshaft and the sensor mounted on the chassis nearby.
>> Edited by sparkythecat on Wednesday 22 June 22:57
parrot of doom said:
Its certainly not normal behaviour.
Not normal, but from my (statistically insignificant) sample of 4 cars looked at as prospecive purchases, sady common - one out of four had a very similar fault. I didn't buy that one, so can't help with the fix I'm afraid!!
>> Edited by Nick_Chim on Wednesday 22 June 23:24
sparkythecat said:
The speedo is electronically driven from the gearbox. Check the wiring to the sensor as its more than likely corroded or loose. That was the problem with mine anyway! Hope that helps.
IIRC that's only on the cars with Rover gearboxes.
The cars with Ford Gearboxes have a toothed wheel on the differential driveshaft and the sensor mounted on the chassis nearby.
>> Edited by sparkythecat on Wednesday 22 June 22:57
Mine has a Rover gearbox and has a sensor mounted above the diff as mentioned earlier, the electronic sensor on the gearbox controls idle.
Chris Smith said:Mine has done this for ages, and has been looked at during a service - not a great problem at low speeds, just a bit frustrating when it stops registering while driving at 'normal' speeds.
Everyone else who is currently having problems: Did your speedos used to work ok at low speeds? In other words, should mine work below 18mph or do they all do that? Thanks.
Chris.
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