Speedo working intermittedly

[SteG]

Out in the sunshine yesterday and the speedo stopped reading for approx 1 mile. Flickered up & down a bit then started working again apparently normally. Presume it's an electronic version taking its message from a speed sensor on the rear wheel. Is the sensor about to through its hand in?

[Jonathan Kay]

If it's the factory's rear wheel type you may not need a new sensor:

1. There's a factory modification to the wiring.
2. There's a Member's procedure for optimising the sensor gap.

Both in the recent archives: let us know if you can't find them.

Jonathan

[SteG]

Thanks Jonathan, will do some digging.

[John Vine]

This is probably the thread JK had in mind.

And this one.

JV
 

[SteG]

Spot on chaps. Will have a fiddle over the weekend. Many Thanks.

[john milner]

For a few years my speedo has played up on some hot sunny days. I have put it down to the actual speedo needing a service.

[IanW]

Mine used to stop working on hot days when the brakes were applied.

Resolved it by fitting LED brake lights, to reduce the power drain, and earthed the sensor to the chassis at the back (probably similar to the aforementioned factory modification).

[SteG]

Having now checked the sensor is OK, I think the earth mod will be the next item on the agenda. Does anyone have a copy of  factory mod WN572 or similar.

Is it coincidence that I fitted a 3rd break light (48 LED) approx 150 miles ago?

[Jonathan Kay]

Does anyone have a copy of  factory mod WN572 or similar.

John Vine has. See the first link in his post for a copy.

Is it coincidence that I fitted a 3rd break light (48 LED) approx 150 miles ago?

Might be related. Where did you tap it in? Is the fault sufficiently frequent to disconnect that and see if it still occurs?

Jonathan

[John Vine]

SteG, I can send you WN572. Just send me a message with your email address. I won't be able to do anything until Friday, though.

JV

[SteG]

Thank John,

I have sent you a message.

Appreciated.

[SteG]

I have (eventually) adjusted the speed sensor gap so the led flashes for the full 360 degree rotation (5 attempts!)

Carrying out earth mod WN572, but does anyone know how to remove the existing earth pin from the terminal block on the loom side? Do not want to destroy the block or splice into the wire.

[JNC]

Follow the workshop mod cut the wire, the tail from the connector seal with heat shrink , join new wire to new earth point.  I did this mod and still needed a new sensor ! Now works fine.  

[John Vine]

The best method, IMHO, is to remove the earth pin from the connector block using a thin-bladed screwdriver, cut off the old wire, and crimp on a new pin to the new earth wire.

Steve, YHM.

JV

[SteG]

Carried out the earth mod and set the sensor - everything was working as normal for about 9 miles and then the intermittent fault returned. Sometimes the speedo worked sometimes it would not, so over a 30 miles route it recorded 18 miles.

Very frustrating.

I suppose a new sensor might be required?

[John Vine]

Frustrating indeed. 

It might be worth checking the continuity (and resistance) of the new earth, from the sensor side of the connector to the chassis. 

It could well be that a new sensor is the answer, but at £60+ it's an expensive experiment!  I suppose you could try asking CC to supply one on sale or return?

Of course, the whole problem might just be down to the speedo itself.  My original problems with erratic speedo behaviour were resolved by replacing the whole unit.

JV

[SteG]

Thanks John, have checked resistance of lead at 0.4 ohm but not from the connector. Continuity from earth point is good to anywhere on the car. Will persevere!!!!!!!!!!! 

[SteG]

It's a new sensor. Speedo now works fine. Best part of £70 though*smash*

[JNC]

Exactly the same as what I did . Apparently CC are looking for an alternative because of so many failures ! 

[Alan Archer]

Morning, well my Speedo stopped working yesterday, reading the archives, am I right in thinking the most likely cause will be a faulty sensor? If so how hard is it to replace?

Alan

[Jonathan Kay]

Morning, Alan.

1. Which type of speedometer? Wheel sensor electronic, rather than gearbox electronic or mechanical?
2. From the archives I'd guess that for the first both poor earth (as in the Workshop Notice) and incorrect gap are more common.
3. Quite easy.

Jonathan

[Alan Archer]

Blimey, I thought you were mind readers :) I don't have a clue, 2005 K series, 5 speed gearbox, standard speedo, it has not skipped a beat, the strange thing is that I recalibrated it last week as changed to 13" wheels, 200 miles later and it has stopped.

Alan 

[Jonathan Kay]

I don't know what was fitted when. But if recalibration only involved pressing buttons then it's one of the two electronic types.

But if last week's work involved disconnecting the instrument or might have disturbed a wheel sensor then I'd check those areas first.

Jonathan

 

 

[John Vine]

AFAIK, a 2005 K has an electronic speedo with the sensor driven off the back of the gearbox.  You can check easily enough from under the car (RHS, in front of the gearbox mount).

I'm not familiar with these.  Do they have the same quill as the mechanical version?  If so, check whether it's broken.  Also, remove the connector and check that the pins are clean and making good contact.

If both quill and connector seem OK, try connecting a power drill to the quill and see (gently!) whether the speedo reacts.  That will help pin things down a bit.

JV 

[Richard Price]

I'm not familiar with these.  Do they have the same quill as the mechanical version?  If so, check whether it's broken.  Also, remove the connector and check that the pins are clean and making good contact.

If both quill and connector seem OK, try connecting a power drill to the quill and see (gently!) whether the speedo reacts.  That will help pin things down a bit.

 

Yes. a 2005 car will still have the gearbox driven sender driven by the quill.

When looking a car with a similar issue. I drove the sender with the quill to drive the speedo to prove the sender and wiring. In my case, it was actually a problem with the drive gear in the gearbox. Fortunately,  the post 2005 speedo is very configurable, and that car now has a proximity sensor looking at prop shaft UJ bolts connected to the existing car loom.