John Attwood Posted May 18, 2014 Share Posted May 18, 2014 Just had a similar problem on my 140 roadsport. The speedo started flickering at around 30/40 then around 70/80 then started telling me I was gong 40 at about 5500rpm in 6th! then died.... First moved the sensor a touch closer with no change, then removed the sensor and had the tiniest about of dirt. All in good working order now. I also noticed it is possible to have the sensor to close and as such you get a dead speedo then as well. Any less than the 1mm and the LED will be on all the time. Edited by - John Attwood on 18 May 2014 16:43:15 Link to comment Share on other sites More sharing options...
Guest Posted May 18, 2014 Share Posted May 18, 2014 I was reading the spec sheet for the sensor today. Telemechanique had the part number listed. They quoted a distance of 2.5mm but I guess that must depend on the lump of metal which triggers the signal. Link to comment Share on other sites More sharing options...
John Attwood Posted May 18, 2014 Share Posted May 18, 2014 Truth be told its a proximity switch not a sensor, so the easy way to set it up in the end is move it just far enough back so it was switching on and off when the wheel rotates, bit of trial and error, but you could equally do it in the other direction, wait till it is off all the time and move it back towards the teeth. It was my first niggle, so i was extremely glad it was such a simple fix!! I had a fear of breaking out the multimeter and trying to work out where the break in the circuit was! Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted May 19, 2014 Share Posted May 19, 2014 Quoting John Attwood: Truth be told its a proximity switch not a sensor ......It is a sensor. Link to comment Share on other sites More sharing options...
John Attwood Posted May 19, 2014 Share Posted May 19, 2014 is it counting the amount of pulses then? - just read up a bit about them and fair enough they are sensors, my bad, but they do have the characteristics of a magnetic proximity switch.....ish... Edited by - John Attwood on 19 May 2014 09:39:55 Link to comment Share on other sites More sharing options...
John Vine Posted May 19, 2014 Share Posted May 19, 2014 Quoting John Attwood: is it counting the amount of pulses then?Well, to be precise, the speedo does the counting -- which is why it's programmable. JV Link to comment Share on other sites More sharing options...
Gregs79 Posted May 26, 2014 Share Posted May 26, 2014 Quoting AndrewB: After a lovely first day blast yesterday it appears I have a dodgy / broken sensor or speedo. Andrew, Same has happened on mine on my first drive out on Friday. Also noticed on return from Caterham that the reversing light isn't working! Slightly concerned reading posts about shorting out, as my while dashboard was replaced! Gregs Link to comment Share on other sites More sharing options...
Guest Posted May 26, 2014 Share Posted May 26, 2014 Take a few spare 7.5 and 10A fuses with you. If it shorts then disconnect the plug of the sender and replace the fuse and you wil get home albeit without a speedo. We are just off for a blat up to Ribblehead and Skipton. Edited - We have just got back having set off at ~9.30 this morning. Had a fantastic drive but the speedo is still not reading right. It does at least work, i.e. it hasn't shorted out, but it only reads okish up to 50 mph then drops to zero. I will keep adjusting the gap but it does seem pot luck. My speedo says I have done 93 miles but I have done nearly 300. Edited by - AndrewB on 26 May 2014 16:49:29 Link to comment Share on other sites More sharing options...
Guest Posted June 1, 2014 Share Posted June 1, 2014 Update on speedo. Since Caterham sent me a replacement speed sensor I have been out half a dozen times with different speed sensor distance settings and no one distance is working perfectly. The best I have is a steady speedo up to 70 ish then it jumps about, drops out and pretty much does as it feels. As you slow down it sorts itself out. Is this looking more than a speed sensor issue or is it a case that they all do that. Andrew Link to comment Share on other sites More sharing options...
John Vine Posted June 1, 2014 Share Posted June 1, 2014 This sounds very like my own experience. It may not be the sensor (or wiring) at all. I suggest you ask CC to send you a new speedo to try out. In my own case, this completely cured the problem. JV Link to comment Share on other sites More sharing options...
Guest Posted June 1, 2014 Share Posted June 1, 2014 Thanks John, I will call them tomorrow. I still need to send the other sensor back so I'll do that tomorrow aswel. Andrew Link to comment Share on other sites More sharing options...
John Vine Posted June 1, 2014 Share Posted June 1, 2014 Hope it works out for you. At the very least, you'll have eliminated one variable. JV Link to comment Share on other sites More sharing options...
Gregs79 Posted June 1, 2014 Share Posted June 1, 2014 Andrew, I have been out in mine again today and found that everything the indicator is switched on the speedo bounces un and down in time with the flashes, so don't think mine is a sensor issue. The car has also died twice now changing between first and second gear, having to restart whilst coasting! That said it said I have filled the car up 3 times and only done 180 miles according to the speedo!! I have done significantly more than that! :-( Gregs Link to comment Share on other sites More sharing options...
Guest Posted June 2, 2014 Share Posted June 2, 2014 That doesn't sound good at all Dominic. I will try the indicator and see if I get the same effect. I will keep you posted with regards a response / solution from Caterham. Glad you are out and about in it. Link to comment Share on other sites More sharing options...
John Vine Posted June 2, 2014 Share Posted June 2, 2014 Quoting Gregs79: ... indicator is switched on the speedo bounces un and down in time with the flashes...Mine did exactly that, too (here). Plus, the needle dropped to zero every time I applied the brakes. I suspected all sorts of electrical gremlins -- in the sensor, in the wiring. It turned out they were lurking in the speedo itself. JV Link to comment Share on other sites More sharing options...
Guest Posted June 2, 2014 Share Posted June 2, 2014 Thanks John, I have definitely seen the needle drop to zero when I brake, just not everytime. Andrew Link to comment Share on other sites More sharing options...
adz Posted June 2, 2014 Share Posted June 2, 2014 I had a speedo that stopped reading if I went over 60ish. was erratic when I indicated and dropped to 0 when I touched the brake pedal. Turned out to be rear lights earth. 2 black ring crimps bolted to the front 3way brake pipe union. unbolted ,cleaned, bolted back up tight, sorted. This obviously needs to be a very good earth, the lights themselves were not dim or behaving erraticaly ( like you see on dodgy trailers ) and the connectors were not corroded, my multimeter was giving a reading of under 0.1 ohm This may not be the cure for your woes, but its an easy thing to try. adam Link to comment Share on other sites More sharing options...
Guest Posted June 2, 2014 Share Posted June 2, 2014 Thanks Adam, I will try that and post back. Link to comment Share on other sites More sharing options...
Guest Posted June 8, 2014 Share Posted June 8, 2014 John, Adam, Dominic, Thanks for the advice and possible fixes. I cleaned the earth on the front brake union and added a large earth cable between the battery and adjacent chassis point to supplement the ones which go to the engine and engine mount. Initially the speedo seemed steadier and worked past 70. However I kept more of an eye on it when indicating and braking and indeed it flickers when indicating and goes to zero when braking. I will get in touch with Caterham tomorrow as it does sound like a speedo problem. TO be fair to Caterham they got in touch with me on Friday to see how I was getting on which is mighty fine customer service if you ask me. Couldn't believe I was able to get out this weekend given the forecast, so glad the weather men (and women) got it wrong. Link to comment Share on other sites More sharing options...
John Vine Posted June 8, 2014 Share Posted June 8, 2014 Sounds like you've done all the usual things, Andrew, so do keep us posted on the replacement speedo. In case CC don't send you calibration details, you'll find what you need here. JV Link to comment Share on other sites More sharing options...
Guest Posted June 15, 2014 Share Posted June 15, 2014 I went for a blat this morning over towards Rivington. On the way their I experienced light drizzle. The wipers worked for a dozen times or so then on the next flick of the switch the fuse popped. Is this likely to be related to the speedo still not working (Works okish for ~13 miles, flicks with indicators, dies with brakes), or is it just a bit of coincidence? When I got back and checked the wiring diagram I saw a note that the brake lights needed a resistor. The note said something like A) Half Mated with 68 ohm (or something) resister. Could it be I am missing the resistor? Where would it be. Having added an LED brake light should I have put a resistor in that leg? The brake lights do work and seem bright. Any thoughts appreciated. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted June 15, 2014 Member Share Posted June 15, 2014 Quoting AndrewB: When I got back and checked the wiring diagram I saw a note that the brake lights needed a resistor. The note said something like A) Half Mated with 68 ohm (or something) resister. Could it be I am missing the resistor? Where would it be. Having added an LED brake light should I have put a resistor in that leg? The brake lights do work and seem bright.What's the whole set-up? Original brake lights with incandescent bulbs and the added high-level LEDs? Or all LEDs? Which lampholder/ loom etc did you use for the high-level LEDs? Jonathan Link to comment Share on other sites More sharing options...
Guest Posted June 15, 2014 Share Posted June 15, 2014 Hi JK I have the original brakes with incandescent bulbs with the cbs led high level light. I found two spare wires by the near side rear arch and connected to those. One black, one black green. I will unplug connectors and see what happens. Edited by - AndrewB on 15 Jun 2014 11:11:02 Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted June 15, 2014 Member Share Posted June 15, 2014 You need to look at the instructions or inside the LED lamp unit to see if it already has the current-limiting resistor. (As you fitted it yourself I'll assume it isn't somewhere in the leads to the unit.) Do you have the CBS model number? Jonathan Link to comment Share on other sites More sharing options...
Guest Posted June 15, 2014 Share Posted June 15, 2014 Jonathan, It was the LEDST8 that I installed to the roll bar. here There was nothing inline on the cable with regards a resister. The unit is sealed and indeed now fixed to the roll bar. I'll try disconnecting the brake light and see what happens. Andrew Link to comment Share on other sites More sharing options...
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