Speed sensor

[pug7]

Out in the 7 yesterday all going well ( except the 2.75 spin during too much right boot doing right turn at traffic lights 😬 ) and the speedo flickered a few times and settled on zero. Just had the car up wheel off with ignition on turnings he hub produced no light on the sensor tried closer and further away but nothing there's a 12v positive and earth on 2 of the pins on the car side of the connector to sensor assume the 3rd feeds back to speedo.

Anyone know if there's a way to test the sensor with a meter? Or know of a cheap replacement supplier Caterham want 63£ seems a lot for small sensor? In mean time driving on the sat nav for speed but the plus being no miles going on the clock

[7TOM]

Hi strange sinario for an electrical failure so may be worth checking the sensor is turning mechanically . To check electrically If it's a hall sensor type your need to scope the signal to the speedo *wavey*as for a cheaper option if it needs replacing there should be a part number on it you could google

[pug7]

It's the sensor by rear wheel the one next to the serrated wheel on hub so no moving parts only the built in led that doesn't light up or flash regardless of distance from the serrated wheel so not sure how you mean about mechanically? As to whether hall type not a clue what your talking about I'm afraid M 😬

Caterham part number is EMP40-1 it's a tad annoying car only went on the road last August and sensor already been replaced once ☹️

[Stationary M25 Traveller]

On a car on the IOM trip a year or two ago it turned out to be the cable to the speed sensor was far too long. The excess was looped and cable tied to the chassis. The ties chafed through the insulation and caused all sorts of problems. Easily resolved with a replacement unit.

[7TOM]

Oh mechanicy wise I was thinking more gear box speed sensor so if that's the case on the hub the toothed wheel is the only moving part so you can rule that out if it intact. The sensor is most likely to be a Hall effect sensor ( like ABS and engine speed sensors)so they need to be scoped to read the signal wire.

[Richard Price]

I recall that these are a Telemecanique part, and looking at the the photo here, the part number that includes "S508B".

 

Part number XS508B1PAL2 looks possible here

 

Can you make out a part number on your existing sensor?

 

Has the face of the sensor been damaged by contact with the serrated wheel? I've seen one where the rear ARB caused loads in the speed sensor bracket which caused sensor damage.

[pug7]

Thanks Richard. On packet for the last replacement is EMP40-1, on the sensor is XS108B3NAL2 from the web best is about £55 inc postage but there with 2m lead, and no one has any stock so might try Caterham later see if they have stock.

No damage to the sensor at all still had 2mm ish gap, tried closer and further but the led in back just doesn't want to come on hence thinking my second sensor failure in 13 months ☹️ only damage I can see is on the wire itself where I've had a Ty wrap a bit tight by look of it. Might try cutting that bit out and splicing it prior to ringing Caterham for new one. Other than that the Tom Tom will have to double as a speedo for now 😬 just odd I've had 2 fail already.

[evotell]

I have adjusted the sensor several times and the speedo still doesn't work. ☹️