How do I fix my speedo?
Discussion
There's a similar thread running on the Chimaera forum but so far no-one's been able to help so I thought I'd try a wider audience.
My speedo in my '98 Chim died a few 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?
Any suggestions would be appreciated
My speedo in my '98 Chim died a few 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?
Any suggestions would be appreciated
If you remove the sensor it doesnt need re-gaping just get it as close to the wheel as possable with out it hitting it. If you need a new one they cost about £60 including VAT, I got mine from the TVR Centre. As for testing it I have no idea. If its the speedo itsself then Speedy Cables is the place to send it.
nervous said:
ive noticed that my mileage is no longer increasing either... is yours? does this mean its more likely to be the sensor or the cable?
According to the bible (page251,) if the speedo and odometer both pack up as mine has, it's much more likely to be a sensor and/or wiring problem than an instrument fault.
Thanks for your post johnnyb. I'm going to dimantle the sensor , clean it and reassemble it to see if that does the trick.
jonnyb said:
tried it, nothing doing.
if i really boot the car (acceleration wise, not kick it) after about twenty mins the speedo will leap into life but it is irratic and not reading correctly. that help?
sorry about the continued banditry
That sounds like the sensor!
Yep, sure does.
ahh, thats grand. thanks lads, I'm gonna get one this avo. where do you folk get yours?
also, any clues on fitting, cos I'm miles away from a dealer? i can see that the sensor is like a bolt thing with a lead coming off (magnetic sensor?), I'm assuming i can just unwind and replace? is there a plug somewhere up in the darkness there that i can just disconnect and connect the new one to?
also, i appreciate that it has to be close, but if its not close enough does this mean the sensor will under-read?
thanks again gang, apologies for the banditry/ endless qus
also, any clues on fitting, cos I'm miles away from a dealer? i can see that the sensor is like a bolt thing with a lead coming off (magnetic sensor?), I'm assuming i can just unwind and replace? is there a plug somewhere up in the darkness there that i can just disconnect and connect the new one to?
also, i appreciate that it has to be close, but if its not close enough does this mean the sensor will under-read?
thanks again gang, apologies for the banditry/ endless qus
Hi lads,
Having the same problem. Changed sensor (£56.13 from dealer). Not fixed problem. You need to cut off the plug to get the wire through a small hole in the underside of the transmission tunnel (surfaces under the rear of the centre console).
Pic of sensor installation, if it helps. Access by removing offside rear wheel.
www.vectix.org/tvr1.jpg
>> Edited by TvrToe on Monday 27th June 18:14
Having the same problem. Changed sensor (£56.13 from dealer). Not fixed problem. You need to cut off the plug to get the wire through a small hole in the underside of the transmission tunnel (surfaces under the rear of the centre console).
Pic of sensor installation, if it helps. Access by removing offside rear wheel.
www.vectix.org/tvr1.jpg
>> Edited by TvrToe on Monday 27th June 18:14
nervous said:
ahh, thats grand. thanks lads, I'm gonna get one this avo. where do you folk get yours?
also, any clues on fitting, cos I'm miles away from a dealer? i can see that the sensor is like a bolt thing with a lead coming off (magnetic sensor?), I'm assuming i can just unwind and replace? is there a plug somewhere up in the darkness there that i can just disconnect and connect the new one to?
also, i appreciate that it has to be close, but if its not close enough does this mean the sensor will under-read?
thanks again gang, apologies for the banditry/ endless qus
David Geralds did ours, involved removing the rear exhaust to get at it, though. The sensor needs to be near the toothed wheel on the diff, if it's too far away, it won't read, too close and the teeth will shorten your sensor!
gudgeon said:
now on my 4th censor cost £80 last time when it goes next time i'm going to the manufacturer of another switch which we use in the machine buisness see if they have something more reliable. pain in the ass...but you got to luv em
Although I've not got mine off yet I'm sure the sensor is only going to be an inductive proximity sensor. You can find out how they work Here
Given the low volume of TVR production, I'll wager they've used some off the shelf sensor rather than having one specifically commissioned for this application.
Now if I can only find out the spec of the one that's on, I should be able to source one a lot cheaper than £80.
Well, it's off!
Came off fairly easily and (despite of what some posters said) without having to remove any of the exhaust or cut any of the wiring.
The end of the sensor looks worn and is slightly dished. I suspect that some abrasive crap must have got between the toothed wheel and the sensor to cause this.
The brass tube has the number z80081 stamped in it and the electrical connecting plug had a sticker on with the number 2071 on.
I've Googled and Metasearched them to death, but have come to the conclusion that probably only TVR know what exactly is in that tube and they're not telling anyone.
Bugger!
I'm thinking of cleaning it up, filing it flat, refitting and re-gapping it, but judging by the number of failures reported on these forums, I'm not optimistic that it'll work.
Can anyone whose fitted a new one remember whether or not that metal in the middle of the sensor should be exposed?
Reports of replacement prices seem to vary between £50 and £80. Where's the best place to buy one?
Came off fairly easily and (despite of what some posters said) without having to remove any of the exhaust or cut any of the wiring.
The end of the sensor looks worn and is slightly dished. I suspect that some abrasive crap must have got between the toothed wheel and the sensor to cause this.
The brass tube has the number z80081 stamped in it and the electrical connecting plug had a sticker on with the number 2071 on.
I've Googled and Metasearched them to death, but have come to the conclusion that probably only TVR know what exactly is in that tube and they're not telling anyone.
Bugger!
I'm thinking of cleaning it up, filing it flat, refitting and re-gapping it, but judging by the number of failures reported on these forums, I'm not optimistic that it'll work.
Can anyone whose fitted a new one remember whether or not that metal in the middle of the sensor should be exposed?
Reports of replacement prices seem to vary between £50 and £80. Where's the best place to buy one?
Would sir like a NPN or PNP output device with or without a preamp filter? 2 or 3 wire? Self powered? What proximity spec do you want? What gapping? Internal or externally switched?
And I haven't even got to the working and switching voltages etc.
There are very many of these devices and actually the price that TVR charge is about the going rate. Especially as it will be the right one for the car.
Don't file the end as the metal filing will kill it. Just clean it.
>> Edited by shpub on Monday 4th July 07:48
And I haven't even got to the working and switching voltages etc.
There are very many of these devices and actually the price that TVR charge is about the going rate. Especially as it will be the right one for the car.
Don't file the end as the metal filing will kill it. Just clean it.
>> Edited by shpub on Monday 4th July 07:48
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