Where is the speed sensor in a 485R

[Madriles]

Hi all

Does anyone know where the is the speed sensor located in a 485R (Duratec 237).

It is not working and the ECU of the engine is in emergency mode, not allowing any more than 4.000 rpm

I'm very far from a Caterham technical service, and in 3 weeks I have a track day in Portimao. Hope I can sort this out

Thank you very much in advance for your support.

 

[simon_h]

It's on the rear axle, right side I think? Same as all the current de-dion cars anyway. Same sensor as well.

[Mark w]

Have a look behind the rear wheel on the rhs 

[Madriles]

Perfect, I'll check out the right rear wheel.

 

Thank you so much

[John Vine]

I'm surprised a faulty or non-working speed sensor could put the ECU in emergency mode.  Are there other symptoms?  Any unusual noises or whines?  Do you have a cat fitted? Does the fuel pump prime for a few seconds and then stop when you first switch on the ignition? 

If you have a Ford dealer nearby, they might be able to read the stored fault codes (if any).

Edited to add:  I'm also beginning to wonder whether the loom is damaged in the vicinity of the sensor?

JV

[SM25T]

We have had cars stop dead on tour after the over-long speedo sensor cable on the rear chassis chafed through. Apparently they share the fuse with something vital.

[CharlesElliott]

I think they share the fuse with the fuel pump, although I guess that isn't the issue here!

[Madriles]

We plugged the OBD generic scan tool to the car, and it showed "Error P500 - failure in the Vehicle Speed Sensor". The speedometer does not work nor the km counter.

We deleted the error but after a short drive it appeared again. And then is when the engine noise changes and does not go beyond 4.000 rpm. Remember the 485 has two engine maps to choose from the dashboard (sport button). In any of them the engine is allowed to go beyond 4.000 rpm

Yes, the car has cat fitted (I bought it last May)

Good suggestion to check a Ford dealer...

Thanks a lot

[mic]

The 485 uses a different ECU. The wheel speed sensor is on the rear wheel and if incorrectly adjusted or faulty will cause the ECU  see a fault and then reduce the rpm etc. 

[John Vine]

Thanks, mic.  That's unusual isn't it - in 7s, at least?

Anyway, what to do about it? 

Assuming your sensor picks up signals from the toothed reluctor ring on the right-hand drive shaft, start by checking that the sensor air gap is around 1mm.  Then turn on the ignition and rotate the right-hand hub.  As each tooth on the reluctor ring passes by the sensor, the LED tip should light up.  If it doesn't, you'll need to check the sensor lead and connector. 

Just a thought -- do you have a Stack dash?  If so, the speed sensor will (I think) be mounted in a bracket on the left-hand front brake calliper, picking up signals fom the disc bolts.

JV
 

[Martin J]

I found my Sigma ran perfectly right across the whole rev range with the speed sensor unplugged. 

I had to fit a new one after the seven year old one fell to pieces. As Ian said they share the same fuse as the ECU. The brand new one lasted one outing then shorted & left me stranded by the roadside with no spare fuses.  After I was recovered home I found the fuse would hold up if the sensor was unplugged. 

I drove around for a while like this (using satnav for a speedometer) until I could swap it out with caterham. (shhh, a handy way of keeping the miles down on your car  shhh)