Hyperactive Speedo

[kalibre46]

Hi,

I clocked over 400 miles this weekend running up to Palmersport and back in the 7. About 90 minutes into the first leg the speedo started going crazy, bouncing between 70mpg and 90mpg whilst I was maintaining 70mph according to the sat nav. Then it got worse, resting on zero then bouncing up to 100mph whenever I blipped the throttle. This continued until I reached my destination.

On the way back it was fine until once again about 90 minutes in it started doing the same thing.

Thought it could be heat related, but I thought it would've reach max temps before 90 mins. Fine this morning on the 30 minute run into Gatwick.

Ideas?

(2012 Supersport 140 5-speed)

[DCL]

If it is 2012 a car, then the chances are the sensor lead is in the process of failing. If the wires short it'll probably blow the dash fuse too. An easy, if not cheap, fix.

[kalibre46]

DCL said:

If it is 2012 a car, then the chances are the sensor lead is in the process of failing. If the wires short it'll probably blow the dash fuse too. An easy, if not cheap, fix.

Thanks for the reply. It's now a couple of months on and it appears to have got worse in that the speedo is rarely reliable on journeys of over 15 minute or so.

Is there a specific part I could order from Caterhamparts? Is it simple to fit? The closest part on CP I could find is:

http://caterhamparts.co.uk/product.php?id_product=...

But being a newbie I haven't got the foggiest if that's the right part.

Many thanks in advance!

[CharlesElliott]

Hi

I'm assuming this is a new(ish) car? If so, the speedo is driven from a wheel speed sensor on the front hub. See the sensor second item down on this page http://caterhamparts.co.uk/search.php?orderby=posi... as well as other bracket etc.

It would be worth checking the mounting of this sensor, if it is close enough to the target, if the connections are secure etc.

Charles

[CharlesElliott]

And sorry, I now see the 2012 in your post. So it will be a wheel speed sensor.

[amk]

Hi,

I have had erratic speedo readings which were a poor earth on the sensor. The sensor earth is bolted to the front 3way brake pipe union , just under nose, passanger side, it's simple enough to undo that , clean and retighten. It may be a cure for you.

cheers
adam

[LB14]

Ive had a similar problem on my 2012 140 Supersport, speedo erratic and eventually the instrument panel fuse kept blowing, which shuts down the ECU and immoblises the car.

I had it into my local trusted mechanic and they eventually traced it to some wiring that had been fastened by cable tie to the wiper mechanism in the build by Caterham (I was not amused!), so every time the wipers were used the wires chaffed.

This then led to the intermittent shorting and hence the fuse blowing. Took some finding by an auto electrician.

[kalibre46]

Thanks for all your replies. I will take a look this weekend and see if I can locate and check/clean the sensor.

CharlesElliott: That link doesn't seem to work for me, do you have the SKU of the part you where referencing?

Many thanks.

[CharlesElliott]

Try NSC106100

[kalibre46]

CharlesElliott said:

Try NSC106100

Thanks Charles.

I've found what I think was the sensor, although it looks nothing like the part shown on the website. Essentially it was a plug connected to various wires cable tied to the frame just next to the three-way brake union. It had another trailing wire that ran through the suspension and disappeared into the wheel assemble area itself, leading me to believe it was the wheel speed sensor. I gave it a good clean although on the inside of the plugs it wasn't grubby at all. I've secured it back and taped up the cables to ensure they are firmly in place. Quick blast up the road and all seems fine, however it was on the longer runs that it manifested itself, so we'll see.

Thanks all again, will keep you posted.